Snoqualmie Vicinity Comprehensive Plan 2006
ELEMENT 5: ENVIRONMENT
TABLE OF CONTENTS
PAGE
A. INTRODUCTION
5-1
B. SENSITIVE AREAS - GENERALLY
5-2
C. WATER RESOURCES
5-3
C.1 SURFACE WATER - GENERALLY
C.2 WATER QUALITY
C.3 LOW IMPACT SURFACE WATER AND STORMWATER MANAGEMENT
TECHNIQUES
C.4 RIVER AND STREAM CORRIDORS
C.5 SHORELINE USES
C.6 FREQUENTLY FLOODED AREAS
C.7 WETLANDS
C.8 AQUIFERS AND CRITICAL RECHARGE AREAS
5-3
5-3
5-4
5-5
5-7
5-7
5-12
5-14
D. FISH AND WILDLIFE HABITAT AREAS
5-16
E. GEOLOGICALLY HAZARDOUS AREAS
5-17
E.1
E.2
E.3
E.4
BACKGROUND
LANDSLIDE AND STEEP SLOPE HAZARD AREAS
EROSION HAZARD AREAS
SEISMIC HAZARD AREAS
5-17
5-18
5-19
5-20
F. AIR QUALITY
5-21
G. CONSERVATION
5-21
G.1 RESOURCE LANDS
5-21
G.2 ENERGY RESOURCES
G.3 WASTE RECYCLING AND REUSE
5-22
5-24
H. URBAN FOREST
5-25
I. HAZARD MITIGATION PLAN
5-26
LIST OF FIGURES
FIGURE
PAGE
5.1
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SENSITIVE AREAS
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A. INTRODUCTION
The natural environment is an important aspect of Snoqualmie’s quality of life. The City and its urban growth area is
blessed with outstanding natural features and therefore has an important stewardship role to perform. The City can
exercise this stewardship through comprehensive plan policies and development regulations that show respect for
natural constraints and serve to protect sensitive natural features and processes. Natural resources and the built
environment should be managed to protect, improve and sustain environmental quality while minimizing public and
private costs.
The water resources, geology, vegetation and wildlife systems characteristic of the Snoqualmie area are interconnected
components of the natural environment. A disturbance in one system can have direct or indirect effects on the others,
including the human system. Within the City and its urban growth area, natural features and processes must be
managed to ensure long term sustainability by limiting or prohibiting development in areas where such activity may
interrupt or degrade natural ecological functions and values, subject people or property to hazardous conditions, or
affect the actual or perceived quality of life in the community. Proper stewardship of Snoqualmie’s natural resources
and sensitive areas is important for maintaining a high quality of life and is considered a high priority for implementing
the Comprehensive Plan.
The Growth Management Act does not specifically require that the comprehensive plan include an environment
element. However, the plan is required to include a plan, scheme or design for:
•
•
Protection of the quality and quantity of ground water used for public water supplies; and
Review of drainage, flooding and storm water run-off in the area and coordination with nearby jurisdictions,
and guidance for corrective actions to mitigate or cleanse those discharges that pollute waters of the state,
including Puget Sound or waters entering Puget Sound.
In addition, WAC 365-195-345, Optional Elements, 3(b) lists Environmental Protection, (including critical, or
sensitive, areas) as an element to be given “strong consideration” for inclusion in the Comprehensive Plan.
Goal 5:
Ensure that natural features and processes which provide functions and values of
public benefit or have inherent ecological value are protected and enhanced, and that
citizens are not subject to potential hazards to health, welfare or property.
Snoqualmie Falls
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B. SENSITIVE AREAS-GENERALLY
The objectives and policies in this chapter recognize the qualitative differences between various sensitive areas. Some
are sensitive because of the hazard they present to public health and safety. Others are sensitive because of the
functions and values they represent for the welfare of natural systems, Snoqualmie and the region. In some cases, the
risk posed to the public or natural system by the use or development of a sensitive area can be mitigated or reduced by
engineering or site design. In other cases, the potential for risk or negative impacts cannot be effectively reduced
except by avoiding the sensitive area.
Natural features and processes which represent limitations to the scope or scale of physical development that can occur
within the Snoqualmie planning area include:
♦ Water and Related Resources
• River and Stream Corridors
• Floodplains and Flooding
• Wetlands
• Aquifers and Critical Recharge Areas
♦ Fish and Wildlife Habitat Areas
♦ Geologically Hazardous Areas
• Steep Slopes
• Erosion Hazard Areas
• Seismic Hazard Areas
These sensitive areas, due to their very nature, require special planning and regulation in order to protect their functions
and values. Sensitive Areas, including wetlands, rivers and streams, aquifers and critical recharge areas, fish and
wildlife habitat areas, and geologically hazardous areas, are regulated by the City’s Sensitive Areas Ordinance, Chapter
19.12 of the Snoqualmie Municipal Code. The 100-Year Floodplain and construction issues pertaining to flooding are
regulated by the City’s Flood Hazard Regulations (SMC 15.12).
Figure 5.1: Sensitive Areas depicts sensitive areas within the City and urban growth area.
Other aspects of environmental quality discussed in this chapter that are important to maintaining Snoqualmie’s quality
of life are air quality and resource conservation.
Objective:
5.B.1
Ensure adequate planning and regulation to minimize conflicts between human uses and sensitve
areas and to achieve, over time, a net gain in the ecological functions, as defined by WAC
173.26.020(12), provided by sensitive areas on a system-wide basis within the City.
Policies:
5.B.1.1
Mitigate unavoidable impacts to environmentally sensitive areas by regulating alterations in and adjacent
to those areas.
5.B.1.2
Provide City officials with the information and authority to protect sensitive areas and impliment the
policies of the State Environmental Policy Act, Chapter 43.21C RCW, the Snoqualmie Vicinity
Comprehensive Plan, and the Growth Management Act of 1990.
5.B.1.3
Ensure the City’s Sensitive Areas Regulations are consistent with the Best Available Science, as required
by WAC 365-195-900 through WAC 365-195-925.
5.B.1.4s
In protecting and enhancing sensitive areas, incorporate the full spectrum of planning and regulatory
measures, including the comprehensive plan, development regulations, stormwater management plans,
and state and federal programs.
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Protect unique, fragile and valuable elements of the environment, including critical groundwater recharge
areas and wildlife and its habitat.
C. WATER RESOURCES
Water can be a powerful physical and chemical force; its movement can shape the form and function of the landscape.
Heavy rainfall typical of the Northwest and the upper Snoqualmie Valley in particular, can result in stormwater runoff
that can scour out river and stream channels, inundate valley floodplains, and flood wetlands. Soil and loose material
picked up in one area is often transported by rivers, streams and flood flows, to be deposited to other parts of the
Snoqualmie Valley, and ultimately to Puget Sound. Chemicals and nutrients dissolved in runoff are carried to wetlands,
over floodplains and downstream. Both overland runoff and groundwater flows may contribute to landslides or other
earth movement that can further alter the physical landscape and pose hazards to people and property. As development
occurs, native vegetation and absorbent top soils are often removed, existing site topography is changed, land becomes
compacted and paved, and natural water courses may be realigned. Such landscape changes can alter the way water
moves, add to existing hazards associated with natural drainage and affect the habitat, recreational, and scenic value of
water resources.
C.1 SURFACE WATER - GENERALLY
Snoqualmie is located in the west-central portion of King County, Washington, in the foothills of the Cascade Mountain
Range. The City lies within the Puget Sound lowland region and experiences a typically mild maritime climate.
Average annual precipitation in the City is 61 inches. Precipitation in the 375 square mile watershed above Snoqualmie
is strongly influenced by the mountain physiography. Snoqualmie Pass receives an average of 105 inches of
precipitation per year.
Water resources within the City and urban growth area include rivers, streams, natural drainage courses, wetlands,
floodplains and aquifers. These resources are important for a variety of purposes, including wildlife habitat, power
generation, recreation, potable water, and disposal of waste water. In some cases, the City must protect itself from
some of the negative impacts of location near a river, such as flooding. Water resources can be managed for multiple
uses, including flood and erosion hazard reduction, fish and wildlife habitat, agriculture, open space, water supply and
hydropower.
Objective:
5.C.1
Manage rivers, streams, floodplains, wetlands, and other water resources within the City for
multiple beneficial uses.
Policies:
5.C.1.1
Ensure that regulatory planning programs that affect rivers, streams, wetlands or other water related
resources within the City are coordinated and that appropriate interrelationships are considered.
5.C.1.2
Coordinate management of rivers, streams, wetlands and other water resources with other affected
jurisdictions.
C.2 WATER QUALITY
The quality of water flowing through streams and rivers is highly important for fish and wildlife that utilize the water as
well as for numerous human uses, and for the protection of the uses of those downstream.
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Objective:
5.C.2s
Encourage the improvement to, and prevent deterioration of water quality.
Policies:
5.C.2.1s
Aggressively enforce all governmental water quality regulations and regulations pertaining to the use of
fertilizers, herbicides, fungicides, and other vegetation maintenance agents near water bodies and
wetlands.
5.C.2.2s
Require the implementation of best management practices to reduce water quality and storm water impacts
of construction and construction related activities in riparian corridors.
5.C.2.3s
Regulate clearing and grading activities to limit the potential for sediment laden runoff to local streams
and wetlands, requiring erosion and sedimentation control best management practices. Use, as a
minimum, the standards of the King County Surface Water Design Manual.
5.C.2.4s
Prohibit significant clearing and grading activities during the wet season, approximately mid-October
through mid-April.
5.C.2.5s
Protect receiving bodies of water from storm and waste water discharge impacts and non-point source
water pollution.
5.C.2.6s
Regularly inspect and maintain stormwater retention and detention facilities to ensure their proper
function. Repair and upgrade these facilities as necessary to solve drainage and stream-flow problems.
5.C.2.7s
Prevent new development in shoreline areas that would adversely affect the ecological functions of the
shoreline by altering water quality.
5.C.2.8
Implement the Puget Sound Water Quality Management Plan to restore and protect the biological health
and diversity of the Puget Sound Basin.
5.C.2.9
Where water quality problems are known to exist, develop short and long-term strategies to reduce or
eliminate the pollution sources. Give particular attention to improving the water quality of Kimball Creek.
C.3
LOW IMPACT SURFACE WATER AND STORMWATER MANAGEMENT TECHNIQUES
The quantity and quality of surface water leaving a developed site must be carefully managed to limit impacts on
receiving water bodies including flooding, siltation and sedimentation, pollutant runoff, and increased temperature.
Traditionally, stormwater is controlled using storm drainage systems and detention ponds that collect runoff from the
impervious portions of a developed site. Detention ponds help to settle sediments and regulate the discharge of
stormwater from the site, but have a number of disadvantages and negative environmental externalities. These include
costly construction, need for regular maintenance for proper operation, changes to the flow regime of a drainage basin,
increasing the temperature of the water leaving the site, and a lack of filtration capability to address finer suspended
solids and chemical runoff.
Municipalities throughout the Puget Sound Region are beginning to use innovative approaches to land development and
stormwater management, termed “Low Impact Development” (or LID), that better preserve the natural environment and
promote natural hydrologic functions. LID strategies use a site’s natural features along with specially designed best
management practices to minimize and manage rainfall runoff at the source. Rather than collecting and directing
rainfall runoff to constructed ponds to manage stormwater flow, remove pollutants and discharge to streams and
wetlands, LID strategies seek to integrate site design, landscaping, natural hydrologic functions and various other
techniques to generate less runoff from developed land and to infiltrate rainfall to underlying soils and groundwater as
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close to where it hits the ground as possible. LID uses a number of practices and design techniques, which include
minimizing street widths, utilizing construction methods and devices that disperse stormwater or collect it for use on the
site, retaining native soils and vegetation, and utilizing pervious paving surfaces.
Objective:
5.C.3
To better protect streams, wetlands, wildlife habitat and groundwater resources, utilize low impact
development techniques wherever feasible to minimize runoff and manage surface water and
stormwater impacts resulting from development.
Policies:
5.C.3.1
Minimize street widths with reduced, but adequate, parking opportunities and access for public safety to
minimize impervious surface.
5.C.3.2
Encourage the use of pervious paving surfaces for parking lots, sidewalks, driveways, alleys, and low-use
roadways.
5.C.3.3
Utilize bio-retention catchments in the design of parking lots and roadways to infiltrate stormwater runoff
on site.
5.C.3.4
Where pervious paving surfaces are used for driveways or sidewalks, gently slope these surfaces away
from the street and towards vegetated strips or bio-retention catchments.
5.C.3.5
Encourage building construction that minimizes impervious surfaces, such as construction on pilings
rather than a solid foundation, locating parking for commercial and multifamily structures under the
building where feasible, and using “green roofs” (roofs that incorporate vegetation to infiltrate
stormwater).
5.C.3.6
Consider adopting impervious surface standards for residential, commercial, and industrial development
to limit the amount of runoff contributing to the stormwater system.
5.C.3.7
For new structures, utilize alternative methods to collect or disperse stormwater other than connection to
the stormwater system. Alternative methods include the use of roof gardens, roof rainwater dispersal
grates rather than gutters, cisterns for the collection of stormwater for on-site uses such as toilets and
landscape irrigation, and on-site retention through the use of catch basins and devices.
5.C.3.8
Limit clearing, grading and soil disturbance outside of the building footprint on newly developed
residential and commercial sites, especially those sites with sensitive features. Reduce compaction and
restore infiltration capacity on already cleared sites whenever practical.
5.C.3.9
To promote natural hydrologic functions, carefully stockpile site topsoil for later redistribution on the site
for yards, landscape areas, vegetated swales and other bio-retention facilities. Topsoil should not be
removed from a development site.
5.C.3.10
Ensure local regulations for surface and stormwater management allow for and encourage LID practices.
C.4 RIVER AND STREAM CORRIDORS
River and stream corridors, also referred to as riparian corridors, consist of the river or stream channel itself, and its
associated regulated buffer. These corridors, including intermittent and ephemeral drainage courses, serve important
and beneficial purposes. They support a multitude of fish and wildlife, purify surface water, store and regulate
stormwater flows, recharge groundwater, maintain open space and provide recreational opportunities and aesthetic
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values. Development can disturb these natural drainage systems and, if not property mitigated, can cause erosion,
sedimentation, pollution, landslides, flooding, destruction of fish and wildlife habitat and damage to surrounding
properties.
The main stem Snoqualmie River, Kimball Creek and Coal Creek are the dominant watercourses in the city and urban
growth area. The Snoqualmie River originates in the Cascade Mountains and is formed by the junction of its North,
Middle and South Forks. These three forks descend through narrow mountain valleys to their mutual confluence at the
foot of Mount Si, about one mile upstream from Snoqualmie. Kimball Creek, which is a tributary to the Snoqualmie
River, begins on the northeast side of Rattlesnake Mountain. It feeds a large wetland south of and adjacent to I-90 and
enters the Snoqualmie River just above the Falls. Coal Creek, which begins on the north slope of Rattlesnake
Mountain, is a tributary to Kimball Creek.
Additional objectives and policies covering shorelines of the state and the jurisdictional area of the shoreline master
program are found in Element 10, Shoreline Master Program.
Rivers, streams and natural drainage courses are regulated by the City’s Surface Water and Stormwater
Management Regulations (SMC 15.80) and Sensitive Areas Ordinance (SMC 19.12). Streams courses are
regulated according to established categories, depending on the flow of the stream, its seasonal continuity, and
whether the stream is used by salmonids. This classification system is detailed in the City’s Sensitive Areas
Ordinance and determines the buffer width and specific regulations applicable to the particular stream.
Objective:
5.C.4
Protect the natural hydraulic, hydrologic and habitat functions, and scenic and recreational values
of rivers, streams and natural drainage courses.
Policies:
5.C.4.1s
Ensure public improvements and private development does not alter natural drainage systems without
acceptable mitigation measures which eliminate the risk of increased flooding, erosion, sedimentation,
habitat loss and related impacts to water quality.
5.C.4.2s
Protect natural drainage systems by controlling the quality and quantity of stormwater runoff. Ensure new
development does not increase peak runoff flows.
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5.C.4.3s
Minimize stream crossings. Whenever possible, require that roadway stream crossings consist of bridges
rather than culverts.
5.C.4.4
New utility stream crossings should utilize techniques that minimize impacts on the stream corridor, such
as bridges, tunneling, or other innovative methods.
5.C.4.5
When significant alterations are being made to existing infrastructure within stream corridors, pursue
design modifications or options for alternative siting that reduce impacts to these sensitive areas.
5.C.4.6
Maintain infrastructure located within stream corridors in accordance with Best Management Practices
that minimize impacts to water quality and floodplain and riparian habitat.
5.C.4.7s
Require that new development adjacent to streams provides an undisturbed corridor sufficient to maintain
the stream corridor’s natural functions and values.
5.C.4.8s
Where a stream corridor contains plant species or provides nesting, rearing or otherwise important habitat
for animal species recognized by the state or federal government as endangered, threatened or sensitive, as
defined by the Washington Department of Wildlife, increase the undisturbed stream corridor in width as
necessary to protect identified species or habitat.
5.C.4.9s
Increase the undisturbed stream corridor in width as necessary to protect corridor functions and values
when slopes greater than fifteen percent, erosive soils or landslide hazards are present.
5.C.4.10
Encourage the restoration of previously disturbed wetland and stream buffers to improve their functions
and values. Maintain restored buffers to limit the reintroduction of invasive species.
C.5 SHORELINE USES
Shorelines in the City are planned for under the Shoreline Master Program, Element 10 of this Comprehensive Plan,
and regulated by the Shoreline Management Regulations (SMC 19.08) and other applicable development regulations of
the Snoqualmie Municipal Code. The Shoreline Master Program implements the requirements of the Shoreline
Management Act of 1971 and regulates development activities along and within designated shorelines of the City.
C.6 FREQUENTLY FLOODED AREAS
Flooding is a natural hydrologic process which has shaped the upper Snoqualmie Valley, providing habitat for wildlife,
and creating rich agricultural lands. Human settlements have historically located in floodplains, taking advantage of the
flat terrain and fertile soils. However, human development often interferes with the natural process of flooding,
affecting the distribution and timing of drainage and resulting in inconvenience or catastrophe. Flood problems
typically increase as human activities encroach upon floodplains and watersheds.
Background
The Snoqualmie River is one of the few remaining unregulated (ie. undammed) rivers in the State. As such, it
experiences the largest peak flows of any King County rivers. The runoff and drainage pattern for the Snoqualmie
River is influenced by its mountainous watershed. The monthly hydrograph shows peaks in December and again in
May and June. This reflects the effect of heavy late autumn and early winter precipitation, which falls as rain or readily
melted snow over much of the basin and produces wintertime peak flows in late November or December. Generally
cooler weather during January and February results in a greater snowpack accumulation and reduced runoff. This is
followed by a classical snowmelt runoff peak in late spring, followed by a late summer to early fall minimum flow
period.
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The combination of high annual precipitation and melting snow in the upper Snoqualmie River basin contribute to the
potential for significant fall and winter flooding. Because the rivers which carry runoff out of this basin are located in
steep valleys, flood waters collect on the flat valley floor where Snoqualmie is located. Although the City occupies less
than one percent of the entire river basin, its location on the valley floor, close to the outlet for the basin, makes it
vulnerable to major flooding which can damage farms, homes or other property. Flooding has been part of the history
of Snoqualmie and the entire Snoqualmie Valley. Major recent floods of record occurred in 1932, 33, 43, 47, 51, 59,
64, 75, 77, 86, 89, 90, 95, and 96. These floods caused millions of dollars in damage and loss of life. The Army Corps
of Engineers estimated the average annual cost of flood damage in the Snoqualmie Valley to be over three million
dollars (1981 dollars).
Overbank flooding frequently surrounds and inundates hundreds of homes and businesses within and around the City.
Flooding in the City of Snoqualmie can be particularly severe for the following reasons:
•
•
•
•
The majority of the existing historic City is located in the floodplain of the Snoqualmie River.
The City is located just downstream of the confluence of the three forks of the Snoqualmie River, and
thus receives the full brunt of combined flows.
Just downstream of the City, the river flows through an area of bedrock prior to discharging over
Snoqualmie Falls. Constrictions in the bedrock block flood flows and frequently cause backwater
flooding to occur.
Kimball Creek flows through the City and into the Snoqualmie River just upstream of the bottleneck
of the Snoqualmie River at Snoqualmie Falls. During flood events, the creek cannot flow out due to
high water levels in the river, creating a backwater flooding effect.
Flood Control Efforts
Snoqualmie has experienced several severe floods that have resulted in millions of dollars in damages to public and
private properties. Following a major flood in 1959, the State requested federal assistance to reduce the flood hazard in
the Snohomish River Basin. In 1960, a feasibility study was authorized by congress and initiated by the Army Corps of
Engineers. The final report, completed in 1969, recommended a major multi-purpose dam on the Middle Fork
Snoqualmie River. However, the proposal met with strong public opposition, based on concerns over impacts to the
Middle Fork’s popular recreation areas and the increased potential for development on downstream farmlands.
In 1974 Governor Evans recommended a process of mediation to resolve conflicts between interest groups and to reach
agreement on how to solve flooding problems. The result of that process was an agreement titled “Recommendations
for Comprehensive Land Use Planning and Flood Control for the Snohomish River Basin,” otherwise known as the
Snohomish Mediated Agreement (SMA). The key elements of the SMA which affected the upper Snoqualmie Valley
were as follows:
•
•
•
A multi-purpose dam on the North Fork Snoqualmie River;
Levees in the Snoqualmie-North Bend area; and
Establishment of Three Forks Park
In 1978, state and local governments, including Snoqualmie, signed an agreement to carry out the SMA and create a 29
member Basin Coordinating Council. At the same time, the Corps of Engineers began studies on the structural flood
control projects recommended in the agreement.
By 1985, the Corps concluded that the North Fork Dam and the Snoqualmie levees were not economically feasible and
the Basin Coordinating Committee had dissolved due to lack of progress on the structural flood control elements of the
SMA. At the request of King County and Snoqualmie, the Corps resumed its study of flood reduction options for the
City. By mid 1987, the Corps had selected channel widening and overbank excavation as the preferred alternative.
While their analysis indicated flood level reductions of up to 3.2 feet for the 100-year flood, the channel widening and
overbank excavation project was also expensive. The estimated cost for constructing the project was $5,777,000, of
which twenty-five percent would be paid by King County and the City of Snoqualmie. Furthermore, possible changes
in downstream flood peaks, which the Corps analysis indicated would be slightly higher and arrive about one hour
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earlier, generated concern for cities below the Falls. It was also anticipated that impacts on riparian habitat and wildlife
would be significant.
In 1989, under the authority granted by Section 205 of the 1948 Flood Control Act (which authorizes the Corps to study
and construct small flood control projects), King County and Snoqualmie asked the Corps to resume the study. The
Corps tentatively concluded the channel widening and overbank excavation project to be feasible, but could not
proceed with analysis or design until local commitment to the project was expressed in a cost-share contract.
The study cumulated in the development of the Army Corps of Engineers Snoqualmie River at Snoqualmie Flood
Damage Reduction Project, commonly referred to as the Corps 205 Project. The project includes three primary
elements. These elements include excavation of two rock outcrops in the Snoqualmie River channel just upstream from
Snoqualmie Falls that currently constrict the flow of water during flood events, and the removal of the abandoned and
partially collapsed railroad bridge crossing the river just upstream from the SR-202 bridge. Implementation of the
project is expected to reduce flood depths by approximately 1.6 feet during a 100-year flood event.
King County and the Army Corps of Engineers signed a Project Cooperation Agreement in December 2002. The City
and King County then signed an Interlocal Agreement for cost sharing for the project, each covering 17.5% of the total
project cost. These two actions committed the federal funding necessary for the project, whose total cost is estimated at
3.1 million. Construction is anticipated to begin in the Summer of 2003, with project completion in Summer 2004.
Flood Hazard Regulation
Primary responsibility for flood damage reduction policy resides with King County. The City is responsible for
enforcing local regulations that are required by Federal and State law and that are consistent with King County
regulations. The County flood damage reduction policy is embodied in the recently adopted King County Flood
Hazard Reduction Plan. The City continues to cooperate with King County in its efforts to find solutions to
Snoqualmie’s chronic flood hazard situation.
Development within the 100-year floodplain is currently regulated by the City’s Flood Hazard Ordinance (SMC 15.12)
and Surface Water and Stormwater Management Regulations (SMC 15.18). The Flood Hazard Ordinance, adopted in
1985, contains strict regulations for new construction in the floodplain and floodway. All new residential construction
in the floodway is prohibited. In addition, all new structures in the floodplain must be constructed with the main floor
at or above the 100-year base-flood elevation. The City also requires the creation of compensatory storage for any new
fill in the floodplain. Snoqualmie also encourages property owners to raise existing homes above the 100-year flood
level. Approximately 30 repetitive loss homes have been elevated to date. In addition, the City has purchased and
removed 14 homes through the FEMA 1362, Repetitive Loss Program.
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Flood Hazard Areas
Flood hazard areas in Snoqualmie are defined as the area subject to inundation by the 100-year flood. The 100-year
floodplain is defined as that area that has at least a one percent probability of inundation in any given year. Streams,
lakes, wetlands, and closed depressions all have floodplains that may also qualify as flood hazard areas. Figure 4.1:
Sensitive Areas depicts flood hazard areas within the Snoqualmie planning area.
A flood hazard area consists of the following components:
•
•
Floodplain. The floodplain is the total area subject to inundation by the 100-year, or base, flood.
FEMA Floodway. The Federal Emergency Management Agency (FEMA) floodway is the channel of the river or
other watercourse and those portions of the floodplain that must be reserved in order to discharge the base flood
without cumulatively increasing the water surface elevation more than one foot. The floodway and floodplain are
delineated on the FEMA Flood Insurance Rate Maps for the Snoqualmie area.
In addition, the Channel Migration Zone of the Snoqualmie River and South Fork Snoqualmie River presents a hazard
of significant erosion and evulsion during flood events. Channel Migration Zones refer to the lateral extent of likely
movement of a river or stream channel along its reach, based on evidence of active channel movement over the past
one-hundred years. The Channel Migration Zones in Snoqualmie have been mapped by King County (Channel
Migration in the Three-Forks Area of the Snoqualmie River Study, January 1996), depicting areas of potential,
moderate, and severe hazard areas for channel migration. The majority of the channel migration hazard areas in
Snoqualmie are found east of the abandoned railroad line to the east of Meadowbrook (The Snoqualmie Valley Trail),
consisting of portions of Three Forks Natural Area, Meadowbrook Farm, and the Mt. Si Golf Course. To minimize
potential hazards from channel migration, uses within the Channel Migration Zone should be limited to parks and open
space uses.
Objective:
5.C.6s
Plan for and take actions that will protect and preserve the City from the effects of flooding while
protecting the floodplain’s capacity to store and convey floodwaters; minimize the risk to life,
property and public health due to the development or other use of flood-prone lands; and prevent
irreparable harm to regionally significant ecological resources in the floodplain.
Policies:
5.C.6.1
Seek to reduce the risk of severe flood hazard and damages experienced by existing properties.
5.C.6.2s
Prohibit new development or other actions that would increase flood risks to existing properties or that is
inconsistent with the City’s floodplain management plans, policies, and Flood Hazard Regulations, or the
King County Flood Hazard Reduction Plan.
5.C.6.3
Meet, and attempt to exceed, the federal minimum standards of the National Flood Insurance Program in
order to better protect public health and safety and to achieve flood insurance premium discounts.
5.C.6.4s
Strictly enforce Flood Hazard Regulations that meet and exceed the minimum requirements established by
FEMA and the Department of Ecology.
5.C.6.5
Allow development in floodplain areas of lesser flood hazard (such as shallow, slow moving water) only
if it can be built to withstand flooding without suffering significant or repeated damage.
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5.C.6.6
Prohibit new subdivisions, residential development and substantial improvements (as defined in SMC
15.12.040) to residential structures within the FEMA floodway.
5.C.6.7
Prohibit new subdivisions, new residential and commercial development and substantial improvements (as
defined in SMC 15.12.040) to residential structures on lands, whether within or outside of the currently
mapped FEMA Floodway, where severe hazards associated with flooding (such as deep and fast flowing
water, large debris, or rapid bank erosion and channel migration) would pose serious threats to life, health
or property.
5.C.6.8s
Require that all new residential construction permitted within the floodplain be elevated to one foot above
the base flood. Consider requiring a margin of safety for the future conditions of the floodplain.
5.C.6.9s
Require that all new non-residential construction permitted within the floodplain is elevated to the base
flood or floodproofed to one foot above the base flood. Consider requiring a margin of safety for the
future conditions of the floodplain.
5.C.6.10s
Do not permit the construction of critical facilities within the floodplain unless there is no feasible
alternative. Require critical facilities permitted within the floodplain to be elevated or floodproofed to
three feet above the base flood.
5.C.6.11
Identify and map areas of severe flood hazard and channel migration zones within the City and urban
growth area.
5.C.6.12
Zone properties located within the channel migration zone of the Snoqualmie River and South Fork
Snoqualmie River for Parks and Open Space uses and seek their acquisition for open space purposes.
5.C.6.13
Classify and regulate areas of severe channel migration hazard as sensitive areas due to their geologic
hazard and importance as fish and wildlife conservation areas.
5.C.6.14
Allow commercial development on existing platted commercial lots in the FEMA floodway, provided, the
development meets all other building, shoreline, zoning and flood hazard regulations; the development is
not within a hazardous area; and the proposed development will not impede flood waters or increase the
potential for additional flood damage to surrounding properties.
5.C.6.15s
Prohibit the placement of structures and/or fill in the floodplain that would cause any increase in the
elevation of the 100-year flood.
5.C.6.16s
Require new development to compensate for capacity to store floodwaters and accommodate potential
surface flow which is lost by structures and fill placed in the floodplain. Compensate for lost capacity by
excavation, within the same drainage area, of equivalent volumes at equivalent elevations.
5.C.6.17s
Require that the average finish grade after construction of a building or structure on any lot or parcel in
the floodplain be no greater than the average grade prior to the construction of such building or structure.
5.C.6.18
Participate with King County, other agencies, and private land owners in developing a basin-wide
approach to solving flooding problems in the upper Snoqualmie Valley.
5.C.6.19
Continue implementation of the Snoqualmie River Flood Control Project consistent with the King County
Flood Hazard Reduction Plan. Implement the project in cooperation with other cities, King County, state
and federal agencies and private interests.
5.C.6.20
Require all proponents of new development to participate with the City to prepare and implement a
specific flood damage reduction plan as necessary to mitigate potential flood impacts from the proposed
development.
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5.C.6.21
Encourage the use of geotechnical filler fabric or other such means that provides an underlayment to
prevent ‘sinking’ of fill in such areas as roadbeds and driveways.
5.C.6.22
Work with FEMA to purchase repetitive loss residential properties within the Floodway that cannot
reasonably be elevated. Utilize these properties for parks and open space.
5.C.6.23s
Prohibit new gasoline, oil, or other petroleum product storage tanks, whether above ground or
underground, within the floodplain, other than those used for heating purposes.
5.C.6.24s
Prohibit any use requiring the storage of any other hazardous substance in quantities greater than those
exempt under the Uniform Building Code within the floodplain.
C.7 WETLANDS
Definition
Wetlands are defined as those areas that are inundated or saturated by groundwater or surface water at a frequency and
duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically
adapted for life in saturated soil conditions. Freshwater wetlands, including marshes, swamps, bogs, wet meadows,
scrub-shrub and forested systems are widespread west of the Cascades. They occur both in association with rivers,
streams, lakes or ponds and as isolated wetlands which exist due to saturated soil conditions. Because of Snoqualmie’s
location in the floodplain, several significant wetlands occur within the City. Some of these are ox-bow ponds and old
channels of the Snoqualmie River.
Functions and Values
Wetlands are recognized as valuable natural resources which perform many important ecological functions and provide
benefits to society. Among the most productive biological systems, wetlands provide important habitat for fish and
wildlife, including essential nesting, feeding, breeding and hiding places. As rich biological systems, wetlands provide
unique educational and scientific research opportunities for the community. In addition, they provide opportunities for
recreation activities such as hiking, hunting, fishing and nature study. Wetlands improve water quality by filtering out
sediments, excess nutrients and toxic chemicals. Wetland vegetation can help stabilize shorelines and reduce
streambank erosion. In many cases, wetlands help recharge ground water supplies and maintain stream flows. Perhaps
most importantly for Snoqualmie, wetlands store and slow flood waters, thereby moderating flood flows. Finally,
wetlands provide a pleasant visual contrast to uniform forested uplands and developed areas.
Wetlands were traditionally regarded as lands of little or no value, unfit for productive use. This view led to a variety of
destructive activities which resulted in a significant loss of wetlands resources. It is estimated that one third to one half
of the state’s wetlands have been lost to various types of development since the turn of the century. Despite protection
efforts, about 2,000 acres of wetlands continue to be lost each year in Washington. In addition, many more wetlands
have been significantly degraded (Washington State Department of Ecology, Growth Management and Wetlands,
Information Sheet, June 1992). The most common destructive development activities in wetlands are clearing,
dredging, draining and filling, which destroy habitat and diminish the wetland’s capacity to store floodwater. Loss or
degradation of wetland resources can therefore result in increased flooding, erosion and related damage. The major
causes of wetland loss and degradation are:
•
•
•
•
•
Urban growth (commercial and residential development, roads)
Dikes and other construction barriers
Erosion, pollution and siltation from increased stormwater runoff and construction activities
Invasion of exotic plants and animals that reduce habitat values for native species
Forestry and agricultural practices
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Wetland Regulation and Inventory
Because of the functions and values they provide, wetlands are regulated and protected by Snoqualmie through the
Sensitive Areas Ordinance (SAO). The Sensitive Areas Ordinance establishes specific buffers for each category of
wetland, providing an undisturbed corridor necessary for the protection of the wetland’s functions and values.
Disturbance or alteration of the wetlands and their buffers is to be avoided, with limited exceptions.
Objective:
5.C.7
Preserve protect and enhance wetlands and wetland natural processes for their hydrologic,
ecological, visual and cultural values.
Policies:
5.C.7.1s
Encourage no net loss of remaining wetlands acreage, functions and values within the City and urban
growth area.
5.C.7.2s
Encourage the creation and restoration of wetlands, where feasible, in order to increase the quantity and
quality of wetlands.
5.C.7.3s
Require adequate mitigation for impacts to wetlands and wetland buffers from development activities and
alterations in and adjacent to wetlands. Utilize mitigation sequencing, giving highest preference to impact
avoidance.
5.C.7.4s
Ensure that development regulations are designed to reduce cumulative adverse impacts to wetland
resources. Class I wetlands should not be altered.
5.C.7.5s
Protect wetland functions and values while accommodating a reasonable use of property.
5.C.7.6s
Ensure adequate regulation of development adjacent to wetlands and wetland buffer areas to protect
wetland functions and values.
5.C.7.7s
Ensure untreated stormwater drainage from public and private development is not directed to wetlands or
their buffers.
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5.C.7.8s
Locate open space areas to protect wetlands. Support the purchase of wetlands on private property for
public benefit.
5.C.7.9s
Encourage the use of incentives such as property tax reductions, conservation easements and other
techniques to preserve wetlands for the public benefit.
5.C.7.10s
Allow development plans to incorporate public access to wetlands when the City has determined that such
access will not degrade the resource and is desirable for establishing interpretive facilities and/or
providing linkages with existing or proposed parks, open space, trails or scenic areas.
5.C.7.11s
Ensure wetland regulations and implementation of mitigation is flexible enough to allow for protection of
systems or corridors of connected wetlands. A tradeoff of small, isolated wetlands in exchange for a
larger connected system can achieve greater resource protection and reduce isolation and fragmentation of
wetland habitat.
5.C.7.12s
Cooperate with King County and other Snoqualmie Watershed jurisdictions to establish a uniform
classification system for wetlands.
C.8 AQUIFERS AND CRITICAL RECHARGE AREAS
Ground water provides an important source of domestic water for Snoqualmie and its urban growth area. It is
contained in underground aquifers, which are sub-subterranean layers of porous rock or earth, and delivered through
such means as springs and wells. Most aquifers are replenished, or recharged, by rainwater.
Two distinct aquifer systems have been identified within the City. One is a shallow unconfined aquifer, located in sand
and gravel deposits associated with the Tokul Creek alluvial fan and post glacial alluvium. The other is a deeper
aquifer located in sand and gravel deposits of pre-Vashon or early Vashon age. The shallow aquifer occurs at depths
less than thirty-five feet. Production from this aquifer appears to be limited to small domestic wells, and yields
approximately 7.5 gallons per minute (gpm). The deep aquifer occurs at depths of approximately 70 to 170 feet. This
deeper aquifer is confined or partially confined and appears capable of producing a sustained, moderate volume of
water. Water yield in the deeper aquifer ranges from 24 to 60 gpm.
Well log data indicate that the shallow and deep aquifers are separated by fine-grained, low-permeability soils. At this
time, there is no data to indicate the two aquifers are connected. The shallow aquifer is primarily recharged by local
infiltration. Primary recharge areas for the deeper aquifer have not been identified, but are suspected to be located
some distance up the Snoqualmie Valley.
Regional Groundwater Protection Planning
The quality and quantity of groundwater is directly related to the aquifer’s recharge area. Groundwater protection
required prevention of contamination and coordinated management of the resource. The City’s ability to identify
potential impacts to ground water from new or existing development depends on the quality of data available on local
aquifers and ground water resources. A good database of ground water information will help define critical aquifer
recharge areas, assist in the definition of wellhead protection areas, and identify aquifer recharge areas.
In April of 1990, the State Department of Ecology designated East King County, including the Snoqualmie planning
area, as Ground Water Management Area No. 14, pursuant to RCW 90.44. The designation authorized King County to
initiate development of a Ground Water Management Plan (GWMP) for the area. A Ground Water Advisory
Committee, which includes representatives of cities, local planning and health agencies, state and federal agencies, and
public and special interest groups, was established to oversee the GWMP process. The City of Snoqualmie participates
in the Ground Water Advisory Committee.
Recharge Areas - Susceptibility and Vulnerability
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The Growth Management Act requires cities and counties to classify aquifer recharge areas according to vulnerability.
Vulnerability is the combined effect of the hydro-geological susceptibility to contamination and the potential for
contamination. A highly vulnerable recharge area would be one where existing or allowed land uses could contribute
contaminants, and hydrologic conditions (e.g. very porous, well drained soils) create high infiltration rates that facilitate
contamination. Low vulnerability is indicated by land uses that do not contribute contaminants that will degrade
ground water, and hydrogeologic conditions that do not facilitate degradation.
Development can threaten both the quantity and quality of ground water resources. Intensive development or industrial
uses can drawdown water supplies and potentially threaten groundwater by contamination. Once ground water is
contaminated it is difficult, costly and sometimes impossible to restore. Groundwater resources must be protected from
contamination to assure potable water supplies, prevent potential risks to public health and avoid costly corrective
measures. Aquifers and critical recharge areas are currently regulated by the City’s Sensitive Areas Ordinance (SMC
19.12).
Objective:
5.C.8
Maintain the long term quality and quantity of ground water resources and ensure that
development activity within critical recharge areas does not degrade groundwater.
Policies:
5.C.8.1
Require that a hydrogeologic assessment of a proposed development site be completed for land use
activities which store or use hazardous substances to determine if such use could cause contaminants to
enter a critical recharge area. Require industries that use hazardous chemicals to have containment
facilities to capture chemicals that might spill or otherwise enter the groundwater system.
5.C.8.2
Work with the State Department of Ecology to provide homeowners and farmers in Snoqualmie with
education and technical assistance on the storage and application of hazardous substances, including but
not limited to, pesticides and fertilizers.
5.C.8.3
Support the development, adoption and implementation of the East King County Ground Water
Management Plan.
5.C.8.4
Identify ground water recharge and well head protection areas and develop planning, zoning and
regulatory measures to ensure that ground water resources are protected from contamination.
5.C.8.5
Work in conjunction with King County to take corrective action to remove contaminant loading due to
failing septic systems and stormwater runoff in susceptible recharge areas, and consider the issue of
mandatory septic tank testing or sewer line connection as an aquifer protection technique.
5.C.8.6
Assure the demand for water to serve the City’s existing and future uses does not exceed the capacity of
the area’s ground water resources.
5.C.8.7
Encourage measures to correct existing problems of groundwater contamination.
5.C.8.8
Participate with the Seattle-King County Department of Public Health to develop policies outlining best
management practices within aquifer recharge areas to protect public health.
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D. FISH AND WILDLIFE HABITAT AREAS
The City and urban growth area contain significant fish and wildlife habitat. As discussed throughout this chapter, river
and stream corridors, wetlands, floodplains and other sensitive areas provide critical habitat for a diversity of plants and
animals. Preservation and protection of these natural features is critical to sustaining wildlife within the Snoqualmie
planning area.
The Growth Management Act mandates preservation of wildlife habitat areas through jurisdictional goals, policies and
development regulations. Through appropriate regulation and sensitive site design, wildlife habitat conservation can be
integrated with human development. The City’s current Sensitive Areas Ordinance contains regulations that promote
protection of fish and wildlife habitat areas and requires native plant communities and wildlife habitat areas to be
integrated with other land uses whenever possible.
The development of Comprehensive Plan policies for wildlife habitat conservation in Snoqualmie considers a number
of issues relative to the integration of development and wildlife habitat. First, all land use actions affect wildlife habitat
in some way. Policies contained within this chapter, the Land Use Element, the Community Character Element as well
as the City’s Comprehensive Open Spaces, Parks and Recreation Plan are intended to provide clear direction for
wildlife habitat conservation. Policies that address the interaction between wildlife habitat, sensitive areas, open space
and land use can help minimize potential conflicts.
It must also be recognized and considered that wildlife do not respect jurisdictional boundaries. The protection of
wildlife and wildlife habitat must therefore be coordinated between adjacent jurisdictions and adjacent landowners.
Maintaining linkages between cohesive blocks of habitat is crucial for wildlife movement, but may be difficult. Further
study, as well as agency and jurisdictional coordination will be necessary to identify key habitat areas and opportunities
to protect or provide linkages. Such linkage networks can also support multiple functions and provide multiple
benefits. Finally, it is important that policies consider protection of common habitat as well as habitat for priority
species (threatened, endangered or sensitive).
Objective:
5.D.
Preserve, protect and enhance wildlife habitat areas within the City and urban growth area.
Policies:
5.D.1
Identify, protect and enhance a viable network of wildlife corridors which link habitat areas together and
encourage the movement of animal species throughout the City and urban growth area.
5.D.2
Cooperate with adjacent jurisdictions to identify and protect habitat networks that are aligned across
jurisdictional boundaries.
5.D.3
Coordinate land use planning and management of fish and wildlife resources with affected state agencies
and federally recognized Tribes.
5.D.4
Identify threatened, endangered and sensitive species and habitat areas within the City and urban growth
area to assure their protection and proper management. Consider habitat management concerns for
candidate and other priority species, as identified in the Washington Department of Fish and Wildlife
(WDFW) Priority Habitats and Species (PHS) program, as part of the balance between development and
preservation concerns.
5.D.5
Require development proposals or alterations in or adjacent to identified fish and wildlife habitat areas
maintain the qualities of the habitat that are essential to maintain feeding, breeding or nesting or other
critical activities of a threatened, endangered or sensitive species using that habitat, and to similarly
maintain or adequately mitigate for the protection of essential habitat used by candidate or other priority
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species (as defined by the Washington Department of Fish and Wildlife Priority Habitats and Specieis
Program).
5.D.6
Strive to increase the number, size, diversity and value of wildlife habitat areas and promote, where
appropriate, the coexistence of native plant communities and wildlife alongside other land uses.
5.D.7
Encourage community involvement in the creation, enhancement, management, interpretation and
enjoyment of wildlife habitat areas and develop public education programs to inform the community on
wildlife and habitat issues and to encourage individual efforts..
5.D.8
Strive to reduce existing levels of air, land and water pollution to support the long term health and
viability of native wildlife species and populations.
5.D.9
Encourage access to sites of wildlife interest, especially for public education purposes, provided such
access does not conflict with wildlife protection goals.
5.D.10
Maintain and enhance natural drainage systems, including associated riparian and shoreline habitat, to
protect water quality, protect fish and wildlife habitat, prevent environmental degradation, and reduce
public costs.
5.D.11
Coordinate with North Bend and King County to develop or revise regulations to manage basins and
natural drainage systems which include provisions to:
a. protect the natural hydraulic and ecological functions of drainage systems, maintain and enhance fish
and wildlife habitat and restore and maintain those natural functions;
b. control peak runoff rate and quantity of discharges from new development to approximate predevelopment rates; and
c. preserve and protect resources and beneficial functions and values through maintenance of stable
channels, adequate low flows, and reduction of future storm flows, erosion, and sedimentation.
E. GEOLOGICALLY HAZARDOUS AREAS
E.1 BACKGROUND
Geologic conditions in the City are primarily the result of continental and alpine glaciation and intervening non-glacial
episodes. The City is underlain by glacial till, sediments of the Tokul Creek alluvial fan, and overbank, channel and
river terrace deposits associated with the Snoqualmie River and its tributaries. Soils at higher elevations within the City
and urban growth area generally consist of very dense glacial till. On the lower slopes, glacial till is mantled with loose
to medium dense alluvial sand, gravel and silt deposits. Near the Snoqualmie River, surface soils are generally
overbank deposits of fine loose sand and silts. Bedrock exposed in the vicinity of Snoqualmie Falls consists of lava
flow and flow breccia which originated during the Tertiary Period, roughly 50 million years ago.
Topography within the existing City is characterized by level, river bottom lands which rise to gentle or moderate
slopes. Elevations range from approximately 1000 feet on the Rattlesnake Ridge property to 410 feet on the
Snoqualmie River floodplain.
Geologically hazardous areas are lands which are susceptible to hazards associated with underlying soils and geology.
Geologic hazards include erosion, landslides, seismic events, soil subsidence and steep slope failure. Development in
areas of geologic instability can pose threats to people and property, increase public costs and jeopardize important
ecological and hydrological processes. Areas of geologic instability are currently regulated by the City’s Sensitive
Areas Ordinance (SMC 19.12).
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Objective:
5.E.1
Act to reduce public costs and to protect public health, property, important ecological and
hydrogeologic functions, and environmental quality from hazards associated with geologic
instability.
Policies:
5.E.1.1
Identify and map areas of potential geologic instability.
5.E.1.2
Require development proposals within areas of geologic instability to further delineate these areas within
the proposed development and provide adequate mitigation in accordance with applicable regulations.
5.E.1.3
Seek to retain areas with slopes in excess of thirty percent as open space, in order to protect against
geologic hazards.
5.E.1.4s
Require a geotechnical report for all development in or proximate to a geologically hazardous area, or
when the development may affect the stability of geological conditions.
E.2 LANDSLIDE AND STEEP SLOPE HAZARD AREAS
Many of the major river valleys in the Puget Sound region are bordered by steep slopes of unconsolidated glacial
deposits and soils which are highly susceptible to landslides. These unstable slopes pose a major hazard to
development and result in considerable property damage each year. The identification of steep slope and landslide
hazard areas is necessary to avoid the risk of injury, property damage and environmental degradation.
The stability of slopes in landslide hazard areas is highly dependent on the water content of the underlying soils.
Where a less permeable layer intersects a slope, water often seeps from the layers above. Water readily percolates
through sand and gravel, but ponds above less permeable silt, clay and till layers, saturating the overlying soils. An
event that increases groundwater levels and flow, such as a rain storm or discharge of surface water above a slope, can
saturate sediments near the surface and cause failure of a slope that is stable under dryer conditions. The combination of
sedimentary deposits, topography, and local groundwater flow results in a high landslide potential. Likewise, erosion
along a stream channel can steepen a slope or expose deposits which may become saturated, thereby increasing the
potential for landslides.
The City of Snoqualmie Sensitive Areas Ordinance defines steep slope hazard areas as those areas where the ground
rises at an inclination of forty percent or greater within an elevation gain of at least ten feet. Slopes of this magnitude
occur in areas around Snoqualmie Falls, on the northern portion of the Snoqualmie Ridge property and on the City’s
Rattlesnake Ridge property. Development is prohibited in steep slope areas. Figure 4.1 depicts steep slope areas within
the City and urban growth area.
The Sensitive Areas Ordinance defines landslide hazard areas according to five criteria:
•
•
•
•
•
Any area with a combination of slopes greater than 15 percent, impermeable soils (silt and clay) frequently
interbedded with granular soils (sand and gravel), and springs or ground water seepage;
Any area of visible evidence of ground water seepage, and which also includes existing landslide deposits,
regardless of slope;
Any area which has shown movement during the Holocene epoch (from 10,000 years ago to present) or which is
underlain by mass wastage debris of that epoch;
Any area subject to instability due to rapid stream incision or streambank erosion;
Any area located on an alluvial fan, which is presently or potentially subject to inundation by debris flows or
deposition of stream-transported sediments.
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Most landslide hazard areas in City and urban growth area involve a few feet of granular surficial soil on slopes
underlain by less permeable till or bedrock. All areas with surface soils underlain with relatively impermeable deposits
which occur on slopes of fifteen percent or greater and with drainage from topographically higher areas, and all areas
with steep slopes of forty percent or greater are identified as potential landslide hazard areas.
Objective:
5.E.2
Protect people and property from the risks associated with steep slope and landslide hazard areas.
Policies:
5.E.2.1
Prohibit development on slopes with a gradient of forty percent or greater.
5.E.2.2
Encourage open space use of landslide hazard areas and maintain such areas in their natural condition,
including preservation of native vegetation.
5.E.2.3
Prohibit development in landslide hazard areas on slopes greater than 40 percent. Do not allow
development on landslide hazard areas on slopes less than 40 percent unless it can be shown that the
development proposal will not decrease slope stability or the hazard can be eliminated or adequately
mitigated.
E.3 EROSION HAZARD AREAS
Erosion is a natural process defined as the wearing away of land surfaces by water, wind or ice. Erosion by moving
surface water is the dominant erosion process in the Puget Sound region. Rates of erosion can be accelerated by land
use modification and development activities. Clearing, grading and weakening of the soil by excavation and filling
during construction, and unmanaged stormwater runoff are factors that frequently contribute to increased erosion.
The susceptibility of soil to erosion depends on its physical and chemical characteristics, slope, vegetative cover, the
intensity of rainfall and runoff velocity. Eroded soil particles are moved by surface water flows and deposited
elsewhere as sediment. Where soil erosion is connected to the surface drainage network, erosion and sedimentation can
result in degradation of water quality and aquatic habitats.
The Sensitive Areas Ordinance defines erosion hazard areas as any slope with an inclination greater than fifteen
percent, and with soils classified as severe or very severe erosion hazards as defined by the USDA Soil Conservation
Service, King County Soils Survey, 1973.
Objective:
5.E.3.
Protect property, surface water quality and fish and wildlife habitat from the negative effects of
accelerated erosion and sedimentation.
Policies:
5.E.3.1
Require the use of Best Management Practices to reduce accelerated erosion and sedimentation due to
construction and construction related activities.
5.E.3.2
Seek to retain as open space areas identified as having severe or very severe erosion potential.
5.E.3.3
Through appropriate land use planning, restrict the scope and scale of development in erosion hazard
areas.
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5.E.3.4
Require new development to minimize grading and restore native vegetation to the greatest extent possible
where development is to occur on sites with high erosion potential.
5.E.3.5
Because of the connection between surface water runoff, erosion and sedimentation, preserve the natural
drainage system, including vegetation and channel corridors, and control runoff from new development in
terms of both peak flows and total quantity.
5.E.3.6
Where possible, seek to restore natural vegetative cover and natural drainage features on degraded sites
which contribute to accelerated erosion and sedimentation.
E.4 SEISMIC HAZARD AREAS
The Puget Sound region is seismically active; hundreds of earthquakes occur each year. While the majority of these
events register a magnitude of 3 or lower on the Richter scale, earthquakes measuring up to 7.1 have been recorded.
Recent studies suggest that historic earthquakes of a magnitude 8 or greater have occurred in the region and that similar
seismic events are possible in the future.
Several major faults are located in the vicinity of the Snoqualmie Valley. Small shallow earthquakes (up to magnitude
4) associated with faults within the Snoqualmie River Basin are likely to occur. Shallow earthquakes of greater
magnitude are expected to occur infrequently in this area.
The City’s Sensitive Areas Ordinance defines seismic hazard areas as those areas subject to severe risk of earthquake
damage as a result of seismically induced landslides, earth adjustments, settlement and soil liquefaction. Loose
saturated soils tend to experience the most severe ground shaking during an earthquake. When shaken, such soils lose
their ability to support a load. Some soils will actually flow like a liquid. Saturated sandy soils such as those on
Snoqualmie River floodplain may be susceptible to liquefaction by shaking during large seismic events.
Most of the floor of the upper Snoqualmie Valley has been identified as a seismic hazard area in the King County
Sensitive Areas Map Folio (December, 1990). Primary seismic hazard areas identified include areas of post-glacial,
modern floodplain river sedimentation. Secondary seismic hazard areas include recessional glacial outwash deposits
along the Snoqualmie River.
Probably the most effective method to assure protection from hazards associated with seismic events is the development
of an earthquake disaster response plan. This plan would designate specific responsibilities to various city officials in
the event a significant earthquake occurs. The plan should also identify the most likely locations for structural failure
and casualties, including hazardous buildings.
Objective:
5.E.4
Seek to reduce the risks to life and property associated with seismic activity in the Puget Sound
region.
Policies:
5.E.4.1
Prepare an earthquake disaster response plan.
5.E.4.2
Require new development to use appropriate measures in site and building design and construction to
reduce risks associated seismic activity.
5.E.4.3
Development located in hillside areas is particularly prone to landslide and rockfall from seismic activity.
Require buildings below steep hillsides subject to earthquake-related subsidence or rockfall hazard to be
set back from the toe of adjacent unstable slopes.
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F. AIR QUALITY
Although Snoqualmie and the upper Snoqualmie Valley are relatively free from air pollution, the City is part of the
larger Puget Sound region, where degraded air quality is an ongoing concern. With the enactment of the Clean Air Act
of 1970, the U.S. Environmental Protection agency established National Ambient Air Quality Standards (NAAQS) for
“priority pollutants.” Given the rural nature of the upper Snoqualmie Valley, it is expected that such pollutants are
primarily generated by automobile traffic and wood burning, and include ozone, carbon monoxide and particulate
matter.
Ozone is a product of photochemical reactions involving hydrocarbons and nitrogen oxides. It is primarily generated
from automobile emissions. Carbon monoxide (CO) is the primary priority pollutant associated with vehicle traffic.
Concentrations of this pollutant are elevated during periods of traffic congestion. Because existing traffic in the City is
generally free flowing and volumes are fairly low, CO levels currently fall within federal standards. Unlike carbon
monoxide, ozone does not reach peak levels closest to the source of emission, but rather at downwind locations.
Particulate matter consists of fine particles of smoke, dust, pollen or other material that remain suspended in the
atmosphere for a substantial period of time. Studies by the Washington State Department of Ecology have shown that
the burning of wood in stoves and fireplaces accounts for more than 80 percent of the fine particulate concentration in
the Olympia area. Wood smoke is also the predominant source of particulates in the Snoqualmie area. Carbon
monoxide is also generated from wood smoke.
Objective:
5.F.
Promote land use, transportation, and technological solutions that have the best chance to reduce
air pollution and assure healthy air quality over the long term.
Policies:
5.F.1
Coordinate with the Puget Sound Air Pollution control Agency and the Puget Sound Regional Council to
develop policies, methodologies and standards that promote regional air quality.
5.F.2
Encourage transportation modes other than single-occupancy vehicles.
5.F.3
Prohibit construction of new residential or commercial structures that use wood stoves or wood heat as the
sole heat source.
5.F.4
Require new development to comply with all applicable federal and state regulations regarding wood
stoves, including only using wood stoves certified by the state pursuant to RCW 70.94.
G. CONSERVATION
Snoqualmie must recognize its responsibility and do its part to conserve resources. With a growing population, larger
land area, increased use of non-renewable resources and less landfill capacity, conservation of resources is becoming
not only a preferred option, but a necessity. Conservation of resources involves proper protection and management of
land and water resources, efficient use of energy, reduced resource consumption, and recycling and reuse.
G.1 RESOURCE LANDS
The protection and management of resource lands in King County is a regional concern and a major objective of the
countywide planning policies. Agricultural, forestry and mineral resource lands should be protected for their long-term
productive resource value. However, these lands also provide secondary benefits such as open space, scenic views and
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wildlife habitat. Resource lands also typically contain an abundance of critical areas that must be protected in
accordance with adopted State and local regulations.
The Growth Management Act contains a goal for conservation of resource lands which states, “Maintain and enhance
natural resource based industries, including productive timber, agricultural and fisheries industries. Encourage the
conservation of productive forest lands and productive agricultural lands, and discourage incompatible uses (RCW
36.70A.020(8)).” The GMA requires jurisdictions protect existing resource lands within their boundaries that have
long-term commercial significance for resource production. Designated resource lands are not to be considered for
urban development. Jurisdictions are further required to enact a program authorizing the transfer or purchase of
development rights for designated resource lands within urban growth areas. The Countywide Planning Policies state
that at the request of any city, King County will work to reinstate the King County Purchase of Development Rights
Program and/or establish an inter-jurisdictional transfer of development rights program to protect these resource lands
in accordance with the Growth Management Act.
The viability of resource activities and businesses is often influenced by the compatibility of adjacent land uses. This is
particularly true of agricultural activities. Conflicts can arise when residential areas are located adjacent agricultural
lands. Farm noises, smells, and operation of machinery are often viewed as objectionable by nearby residents. For
conservation of resource lands to be effective, it is important to minimize conflicts among resource uses and other
adjacent land uses.
Objective:
5.G.1
Encourage the retention of agricultural, pasture and forest lands capable of long term production.
Policies:
5.G.1.1
Support the retention of farming and ranching as a functional and visual ingredient of the rural setting.
5.G.1.2
Support working forests while discouraging forest practices that would adversely impact the environment
or community.
5.G.1.3
Encourage clustering of residential lots as a means of conserving productive farmland and agricultural
soils resources.
5G.1.4
Discourage extension of sanitary sewers and other urban services through agricultural lands except to
remedy septic system failures in existing residential neighborhoods.
5.G.1.5
Encourage utilization of natural resources through methods that minimize impacts on secondary benefits
such as open space, scenic views and wildlife habitat.
5.G.1.6
Through appropriate land use planning, encourage compatible land uses to avoid conflicts which might
arise from non-resources land uses located adjacent to natural resource areas.
5.G.1.7
Require mineral extraction and processing operations and agricultural practices to implement best
management practices to reduce environmental impacts and mitigate any unavoidable impacts.
G.2 ENERGY RESOURCES
Oil and gas are fossil fuels which come from finite reserves created by the decay of plants over millions of years.
These resources cannot be regenerated on a human time-scale. In contrast, renewable energy sources come from
natural flows in the regional environment, such as solar, wind and hydropower. Together with improvements in the
efficiency of all energy use, renewable sources can supply a greater proportion of the City’s energy needs.
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A greater dependence on renewable sources of energy also represents quality of life benefits for local citizens.
Renewable energy technology produces much less pollution than conventional technology, resulting in cleaner and
healthier air, water and land. Conservation of energy through increased efficiency also results in lower energy costs.
While conversion to renewable sources may have higher initial costs, once in operation they cost much less to run
because the fuel is free. With energy efficiency and use of local renewable sources, much of the work associated with
energy production takes place in the community or region where the energy is to be used. Thus, money spent on energy
keeps circulating in the area, creating more jobs through a ‘multiplier effect.’
Housing
The most significant energy conservation action a local government can do in regard to housing is provide the
opportunity for more compact and diverse housing. Building compact housing requires less land and can help achieve
other conservation goals such as air quality, open space, preservation of farmland, reducing traffic congestion and
lower costs of building new infrastructure. Building diverse housing (e.g. single-family homes, duplexes, townhouses,
apartments, etc.) provides a range of housing choices. Because many of these homes are smaller and share common
walls, they tend to be more energy efficient.
Solar Access
Energy from the sun can be used to reduce the need for electricity and fossil fuels in two ways. First, through passive
solar design - proper building orientation and design that takes advantage of the sun for lighting and heating in the
winter, and reduces heat gain and cooling needs in the summer. Second, active solar energy systems that collect the
sun’s energy, usually through panels, for water and space heating and electricity. Protecting solar access helps ensure
that both passive and active systems can be used effectively.
City Facilities and Vehicles
Many local governments have taken steps to increase energy efficiency in public facilities. Energy efficiencies in City
facilities can be gained through consideration of specific energy and water saving technologies, and operation and
maintenance practices in regard to heating, lighting air conditioning and plumbing systems; efficient wastewater
treatment; and vehicle fuel efficiency.
Objective:
5.G.2
Promote conservation of energy through increased efficiency and a transition to renewable sources
of energy.
Policies:
5.G.2.1
Participate in requirements of the Northwest Energy Code.
5.G.2.2
Assist in the effort to reach low-income households eligible for free weatherization through existing
programs.
5.G.2.3
Promote the use of solar or other renewable energy sources.
5.G.2.4
Demonstrate applications of energy efficiency and renewable energy use in municipal buildings.
5.G.2.5
Encourage developers to divide land in such a way that houses can be oriented to maximize solar access
while minimizing shade to adjoining properties.
5.G.2.6
Operate and maintain the City’s vehicle fleet to improve fuel efficiency and reduce costs. Consider
vehicles that use alternative fuel sources for greater energy efficiency and lower pollution.
5.G.2.7
Adopt a water conservation program in order to reduce the amount of wastewater to be treated.
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5.G.2.8
Participate in energy conservation awareness programs which distribute educational information and
sponsor energy education programs on conservation and renewable energy.
5.G.2.9
Provide for the efficient use of water and energy through the use of natural drainage, landscaping with
native and drought tolerant species, energy efficient siting of building construction and recycling.
G.3 WASTE RECYCLING AND REUSE
Cities and towns produce large quantities of garbage, much of which citizens pay to have hauled away to landfills or
incinerators. Recycling and reuse are alternatives that make use of those resources, and at the same time reduce the
drain on rural areas and resource lands to supply new raw materials.
Recycling and reuse refer to salvaging discarded materials rather than burying or burning them. Materials may be
reused in their original form, reused for a different purpose, decomposed organically or reprocessed. As with energy
conservation, recycling and reuse provide benefits to the city and its residents. By reducing the total volume of the
waste stream to be transported, recycling programs can be cheaper than the cost of dumping garbage in landfills and
can also eliminate the need for incineration, which has high capital and environmental costs. Recycling cuts the
demand for raw materials that are typically brought from rural and wilderness areas, such as wood fiber and primary
metals. Composting of organic wastes allows nutrients to be returned to the soil.
While many local governments have established effective curbside recycling and yard waste programs for residential
areas, household recycling is just one step toward meeting the waste diversion goals. Commercial waste usually
comprises more than half of the total waste stream. Adequate space and access for recycling is necessary in multifamily housing, and commercial and industrial buildings. In addition, demolition and construction activities also
present opportunities for reuse and recycling.
Objective:
5.G.3
Encourage, educate and provide incentives for residents and businesses to conserve natural
resources through waste reduction, recycling and reuse.
Policies:
5.G.3.1
Support the expansion of city-wide recycling programs whenever feasible.
5.G.3.2
Offer incentives to residents to reduce the amount of material going into the waste stream by providing
recycling programs with a rate structure that increases according to the amount of waste material that is
collected.
5.G.3.3
Coordinate with other agencies to provide educational materials and programs on composting for City
residents.
5.G.3.4
Require owners of new multi-family, commercial and industrial buildings, and encourage owners of
existing multi-family, commercial and industrial buildings, to provide space for separating and storing
recyclable materials.
5.G.3.5
Consider the re-use and recycling of demolition debris in demolition activities undertaken by the City
directly or by contract.
H. URBAN FOREST
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Urban forests occupy approximately 70 million acres in the United States. It was estimated that by the year 2000, more
than 80 percent of the population would live in urban areas. Snoqualmie’s urban area has more than doubled since
1995, as growth and development in the city replaced rural forest lands. Over the next 20 years, the city’s urban area
will continue to expand, with additional forest lands converted to streets, housing, parking lots, business areas, and
active parks. Urban community forestry can play an important role in enhancing community vitality and the quality of
life for the City.
Trees in Snoqualmie’s small town urban environment are a valuable public resource. More than just “extra” amenities,
trees and natural landscape areas enhance the character and quality of our local landscape of streets, neighborhoods,
shopping areas, workplaces, schools and parks, and provide a backdrop for our everyday and leisure activities. Besides
natural beauty, trees can provide buffers and help to soften the impacts of buildings and streets. They offer shade from
summer sun, protection from winter weather, and reduce noise and glare. Their leaves and needles filter pollutants
from the air and intercept rainfall, helping to reduce stormwater runoff. Trees prevent soil erosion and reduce siltation
and flooding. They provide habitat for birds and other wildlife and can grow food and materials for human use. In
addition, trees increase property values, and help promote tourism and local business trade.
The character of the older areas of Snoqualmie is enhanced by a rich assortment of evergreen and deciduous trees
located along streets, in yards and landscape areas, and within natural areas along the Snoqualmie River, streams and
wetlands. The landscape is punctuated by mature trees of various species and sizes, both native and non-native, which
have been cultivated and cared for over many years. These trees provide a sense of continuity with the past and
contribute to a green and healthy community. In recent years, large areas of forest have been cleared for new
development. While natural forest has been preserved in sensitive areas and buffers, and trees have been planted on
every new street and in every new park and landscape area, the natural forest landscape has been diminished.
The City of Snoqualmie should encourage the preservation and maintenance of trees on both public and private
properties by protecting trees from unnecessary removal or damage during development, and by promoting the
continued planting of new trees, particularly within new development. The protected and enhanced urban forest will
give character to the City’s neighborhoods, shopping districts and recreation areas, provide attractive streets for
pedestrians, and weave a tapestry of wooded corridors through the community for the enjoyment of people and wildlife.
As we care for and add to Snoqualmie’s urban forest, we will create a special “sense of place” for the City and leave an
important legacy for future generations.
Objective:
5.H.1
Promote the preservation and maintenance of trees on public and private lands and promote
the planting of new trees within in the City to support other land use objectives, promote
beauty and environmental health, provide habitat for wildlife, and take advantage of the
economic value contributed to the City by its urban forest.
Policies:
5.H.1.1
Ensure that trees are an important part of public investments being made for economic development
and redevelopment activities.
5.H.1.2
Plant street trees on all new streets and ensure that they are a priority for any improvements planned
for existing city streets.
5.H.1.3
Plant street trees to create a pattern of visual continuity and order and to provide a strong edge to the
street corridor, and to help foster a sense of neighborhood identity.
5.H.1.4
In constructing new street and landscape tree plantings, use species appropriate to the urban setting.
Consider hardiness, traffic safety and sightline restrictions, pedestrian safety, potential for damage to
property, conflicts with existing and proposed utilities and contributions to habitat in tree placement,
size, and species selection.
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5.H.1.5
Design and place new sidewalks, overhead wires, and underground utilities to minimize impacts on
existing or proposed trees in the public right-of-way and on private property.
5.H.1.6
Identify, protect, and maintain existing trees with historic significance or other value to the whole
community, as well as to specific neighborhoods.
5.H.1.7
Give special care and protection to large, historic or otherwise unique trees in the downtown district,
such as those within Railroad Park, along Railroad Avenue near the Depot, and the old “Town Pump”
magnolia.
5.H.1.8
Establish an Urban Forestry program that provides education, encouragement and assistance for
planting, maintaining and preserving trees on private property and street frontage planter strips.
5.H.1.9
Ensure that the preservation of existing significant trees is an important consideration in the site
planning of development projects, including determining the location and configuration of buildings,
roadways, and parking areas.
5.H.1.10
Balance objectives for tree preservation with considerations of solar access, wind protection or shade
within a development and/or on adjacent property.
5.H.1.11
Ensure that sizes, densities and placement of trees be commensurate with the scale of parking areas
and help reduce the visual impact of these parking areas.
5.H.1.12
On lands being converted from timber production, integrate trees preserved in naturalistic settings in
the development of the property.
5.H.1.13
Ensure that trees are planted according to current professional standards to minimize mortality and
maintenance costs.
5.H.1.14
Ensure existing urban trees and tree plantings are maintained in a way to promote their health and
longevity.
5.H.1.15
Use native tree species as much as possible to enhance habitat and support retention of a more natural
landscape character.
5.H.1.16
Buffer residential neighborhoods from the adverse effects of principal arterial roadways by using
stands of existing trees and by planting new trees.
5.H.1.17
Develop a Forest Management Program that utilizes sustainable best practices to manage the city’s
natural open space.
5.H.1.18
Encourage Forest Stewardship through education, outreach and incentive programs.
I. HAZARD MITIGATION PLAN
In addition to those natural hazards identified in this Element, the City of Snoqualmie prepared a Hazard Mitigation
Plan in 2003 to evaluate and plan for a number of natural hazards, including flooding, landslides, severe local storms,
fire and earthquakes. The plan provides a vulnerability assessment of uses and capital facilities for each of the hazards,
and provides mitigation policies and strategies to address the issues of vulnerability. The plan contains an action
program that identifies specific projects to implement the recommendations of the mitigation policies and strategies.
This Environment Element, and the Snoqualmie Vicinity Comprehensive Plan, references and incorporates the Hazard
Mitigation Plan.
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