Nottawasaga Valley Conservation Authority
2009 Groundwater Overview
What is groundwater?
Contrary to popular belief, groundwater is not an underground
river or lake. It is water that is stored underground in bedrock
fractures or between sand/gravel grains. These underground
storage areas are called aquifers. Where sediments have been
deposited in layers, there can be a vertical series of aquifers,
separated by fine-grained silts or clays (aquitards) which tend to
block the downward movement of water. Aquifers located below
aquitards are somewhat protected from potential contamination
from the surface and are typically preferred for drinking water
sources. Naturally occurring minerals in bedrock or sediments
may occasionally affect the appearance, smell, or taste of
groundwater.
Where does groundwater come from?
Photo: OMAFRA
Groundwater is part of the water cycle. Water enters the landscape from rain and snowmelt. Some of this water runs directly into lakes and streams. Some is lost to evaporation and
evapotranspiration (evaporation from trees and other plants). The remainder of the water sinks into the soil, passing through plant
roots into the water table (where soils/sediments are saturated) where it becomes groundwater. Downward passage of water into
the shallow water table may be rapid – a matter of hours. Passage into the lower aquifers may take weeks, months or years.
Groundwater is dynamic, moving from sand/gravel recharge areas (where large amounts of water enter the groundwater system) to
spring and seep discharge areas which feed streams and wetlands.
Why is groundwater important?
Groundwater is essential for a variety of human and ecosystem uses. It supports municipal water supplies, private water supplies
and irrigation on some valuable farm lands. For rural residents relying on individual wells, groundwater is often the only available
water supply. For many communities, it is by far the least expensive option for public water systems.
Groundwater maintains stream flow and wetland
levels during dry spells and is vital to the
maintenance of ecological functions and
biodiversity. Brook trout, a highly sensitive fish
species, depend on groundwater to keep stream
flows cool through the summer and to provide a
hospitable habitat for their redds (nests) through the
winter months.
Pretty River
Endangered species such as Eastern Prairie Fringed
Orchid need stable wetland groundwater levels to
survive. Groundwater, in part, sustains globally rare
coastal marsh communities along the Nottawasaga
Bay shoreline.
Eastern Prairie
Fringed Orchid
This overview describes groundwater conditions within the Nottawasaga Valley Conservation Authority watershed and provides stewardship
actions to help maintain the health of the system. More NVCA watershed reports can be found on the NVCA website (www.nvca.on.ca).
Partner Municipalities: Township of Adjala-Tosorontio, Township of Amaranth, City of Barrie, Town of the Blue Mountains, Town of
Bradford West Gwillimbury, Township of Clearview, Town of Collingwood, Township of Essa, Municipality of Grey Highlands, Town of
Innisfil, Township of Melancthon, Town of Mono, Township of Mulmur, Town of New Tecumseth, Township of Oro-Medonte, Town of
Shelburne, Township of Springwater and Town of Wasaga Beach.
“Conserving our Healthy Waters”
Groundwater in the NVCA Watershed
The NVCA watershed supports more
than 130 municipal wells, 10,000
private wells and approximately 373
large surface water and groundwater
users. With the exception of
communities serviced by the Town of
Collingwood surface water intake
(Georgian Bay), the remainder of
watershed residents are solely
dependent on groundwater resources
for water supplies.
Areas with potential for groundwater contamination
The groundwater systems of the
watershed can be broadly divided into
two areas – bedrock systems
associated with the Niagara
Escarpment (and areas west) and deep
overburden (unconsolidated
sediment) areas associated to the east
(south and central Simcoe County).
The bedrock aquifers west of the
Niagara Escarpment correspond to the
Amabel dolostones which
regionally are characterized by good
drinking water. This unit may exhibit
extensive fracturing where the
overlying soils are thin, resulting in
karst topography (i.e. caves), which is
locally more vulnerable to
contamination. The front of the
Niagara Escarpment is also recognized
for extensive seeps and springs where
groundwater discharges from the
Escarpment face into local streams.
This groundwater discharge supports
healthy trout streams throughout the
Escarpment area .
South and central Simcoe County is
characterized by deep, multilayered
sediment deposits from past glacial/
postglacial activity resulting in a
series of vertical aquifers separated by
layers of silt/clay (aquitards). Aquitards provide protection for municipal well supplies. Groundwater discharge occurs on the
flanks of the ancient Algonquin shoreline, Oro Moraine and Oak Ridges Moraine, and supports trout streams, significant deer
yards (conifer swamps) and rare fens associated with the Minesing Wetlands.
Areas where groundwater is particularly vulnerable to contamination have been mapped and generally correspond to shallow
aquifers which lie close to the ground surface. In these areas, nitrates from septic systems, E. coli from various sources and
sodium and chloride from road salting are potential sources of contamination that may impact groundwater quality.
Groundwater Monitoring
Source Water Protection
The Clean Water Act is part of the Ontario government's
commitment to implement all of the recommendations of the
Walkerton Inquiry, which resulted from the tragic loss of life
related to groundwater contamination in Walkterton. For the
first time, communities will be required to create and carry out
a plan to protect the sources of their municipal drinking water
supplies. This will take place through the development of
source water protection plans, which will:
• identify the sources of drinking water, including
municipal wells, river and lake intakes
• outline threats to the quality and quantity of water in
source areas and propose actions needed to reduce
those threats and protect source water
The planning process entails the development of a Terms of
Reference, an Assessment Report, and the Plan. The NVCA is
working with its partners in the South Georgian Bay-Lake
Simcoe Source Protection Region to develop the Assessment
Report. Current activities include the development of a water
budget, a threats inventory list, and the delineation of groundwater and surface water vulnerable areas.
Groundwater quality monitoring
Through the Provincial Groundwater Monitoring Program (PGMN) partnership
with the Ministry of the Environment, the NVCA monitors water levels and water
quality in 15 wells located in various aquifers throughout the watershed. Baseflow
monitoring in watershed streams provides a measure of groundwater discharge.
Monitoring data allows the NVCA to track changes in groundwater quantity and
quality over time. Changes can then be assessed against precipitation, water use
and other data to identify potential causes of change. This information can be used
to assist in making sound land-use planning decisions and to develop scientificallybased groundwater policies and groundwater management programs.
Water quality monitoring began in 2003 and is now being conducted annually. Results to date indicate that water quality
parameters in all monitoring wells meet Ontario Drinking Water Quality Standards. Some wells are showing levels of iron and
manganese that are slightly above aesthetic objectives (not health-related) due to natural background concentrations in the aquifer sediments. Elevated sodium levels (though not above water
quality standards) have been observed in shallow wells near Highway 400 and in Barrie.
Additional data collection at the PGMN wells is required to interpret and discuss broad groundwater quality trends in watershed aquifers.
The PGMN wells are located in areas that are generally outside of human influences and are
intended to monitor the broad health of aquifers rather than to track potential problem areas.
Water quality monitoring results from these wells should not be used to infer that water quality in
private or municipal well systems is satisfactory. Private well owners are encouraged to
regularly submit water quality samples from their wells to the local health unit (see reverse
for contact information) for biological analyses (e.g. E. coli), and Well Wise for analyses of
non-biological parameters (e.g. metals).
Niagara Escarpment Monitoring
In partnership with the Niagara
Escarpment Commission, a baseflow and
water quality study was undertaken on
key streams along the Niagara
Escarpment during the summer and fall
of 2008.
This study pinpoints
significant groundwater discharge along
the Escarpment areas and will support
Measuring baseflow
effective land use, fish habitat managein the Pine River
ment and source water protection
planning.
Strong groundwater
discharge in this area supports stream
flows and cool stream temperatures
during the summer months which are
required to support resident and
migratory trout and salmon populations
in Escarpment streams. Maintaining this
habitat is essential to the protection of
Brook Trout in the Pine River
this resource. The Nottawasaga River
provides the most extensive migratory
trout and salmon habitat system in the Great Lakes basin!
Stewardship Opportunities
Activities on the land surface can affect groundwater quality. Because water seeps from the soil surface, contaminated surface
water can infiltrate into the ground, affecting local aquifers. Fertilizers, household cleaners, human and animal waste, underground
storage tanks as well as hazardous wastes can contaminate groundwater. You can help improve groundwater quality by examining
your actions and considering their effects on water quality. Ways to help improve groundwater conditions include properly
locating, constructing, and maintaining wells and septic systems, conserving water, minimizing household waste, and limiting the
use of fertilizers and pesticides. Remember that once contaminated, groundwater is extremely difficult to clean up: prevention is
the key!
The NVCA currently offers stewardship opportunities through the Healthy Waters Program and the Ontario Drinking Water
Stewardship Program. Depending on your location and project, you may be eligible for funding for:
♦
Decommissioning unused wells and upgrading existing wells
♦
Septic systems inspections and upgrades
♦
Agricultural runoff and erosion protection
♦
Business and industry pollution prevention reviews
For more information, please contact the NVCA’s Stewardship Services at (705) 424-1479 ext. 239 or visit www.nvca.on.ca
Additional contact information
Well Wise - (905) 983-9911
Simcoe Muskoka District Health Unit
Tel: 705-721-7520
www.simcoemuskokahealth.org
Wellington-Dufferin-Guelph Health Unit
Tel: 519-846-2715
www.wdghu.org
Grey Bruce Health Unit
Tel: 519-376-9420
www.publichealthgreybruce.on.ca
Thanks to our Watershed Champions—our landowners, community groups, schools, businesses and
government agencies—that support stewardship activities in our watershed!
Contact NVCA staff at (705) 424-1479 or at www.nvca.on.ca to get involved!