Colorado Ag. Science
Curriculum
Section: Plant and Soil Science
Unit: 5 - Environmental Factors
Lesson: 5
Water Quality and Pollution
WATER QUALITY
STANDARDS
• Water Quality Standards are a critical part of working
towards the goal of fishable/swimmable waters in the
United States.
• Water quality standards are the foundation of the water
quality-based control program mandated by the Clean
Water Act.
• Standards help to identify water quality problems caused
by, for example, improperly treated wastewater
discharges, runoff or discharges from active or
abandoned mining sites, sediment, fertilizers, and
chemicals from agricultural areas, and erosion of stream
banks caused by improper grazing practices.
WATER QUALITY
STANDARDS
• A water quality standard consists of four basic
elements:
– 1) designated uses of the water body (e.g.,
recreation, water supply, aquatic life, agriculture),
– (2) water quality criteria to protect designated uses
(numeric pollutant concentrations and narrative
requirements),
– (3) an antidegradation policy to maintain and
protect existing uses and high quality waters, and
– (4) general policies addressing implementation
issues (e.g., low flows, variances, mixing zones).
CLEAN WATER ACT
• Growing public awareness and concern for
controlling water pollution led to enactment of
the Federal Water Pollution Control Act
Amendments of 1972.
• Amended in 1977, became the Clean Water Act
at that time.
• Established the basic structure for regulating
discharges of pollutants into the waters of the
United States.
• Unlawful for any person to discharge any
pollutant from a point source into navigable
waters, unless a permit was obtained under its
provisions
DESIGNATED USES
• The water quality standards regulation requires that
States and authorized Indian Tribes specify appropriate
water uses to be achieved and protected.
• Appropriate uses are identified by taking into
consideration the use and value of the water body for
public water supply, for protection of fish, shellfish, and
wildlife, and for recreational, agricultural, industrial, and
navigational purposes.
• In designating uses for a water body, States and Tribes
examine the suitability of a water body for the uses
based on the physical, chemical, and biological
characteristics of the water body, its geographical setting
and scenic qualities, and economic considerations.
ANTIDEGRADATION
• The water quality standards regulation requires
States and Tribes to establish a three-tiered
antidegradation program.
– Tier 1 maintains and protects existing uses and water
quality conditions necessary to support such uses
such as fishing and swimming. Tier 1 requirements
are applicable to all surface waters.
– Tier 2 maintains and protects "high quality" waters -water bodies where existing conditions are better than
necessary to support "fishable/swimmable" uses.
– Tier 3 maintains and protects water quality in
outstanding national resource waters.
AGRICULTURAL RUNOFF
• Agricultural runoff refers to the total loss of water
from a watershed by all surface and subsurface
pathways.
• The term “agricultural runoff” encompasses two
processes that occur in the field – surface runoff
and subsurface flow.
• Surface or overland flow can infiltrate into a soil
during movement down a slope, move laterally
as interflow, and reappear as subsurface flow.
SURFACE RUNOFF
• Surface runoff from grass, forest, noncultivated
soils carries little settlement and is, therefore,
generally dominated by dissolved Phosphorous
(about 80 % of P loss).
• This release occurs when rainfall or irrigation
water interacts with a thin layer of surface soil (1
or 2 inches) and plant material before leaving
the field as surface runoff.
• Runoff water may contain pollutants
– Nonpoint – source of contamination unclear
– Soil, fertilizers, pesticides, manure, pathogens
How pollution occurs …
•
•
•
•
Human activities – of greatest concern
Wildlife may spread pathogens
Plant growth and decay
Dissolved minerals and gasses
POLLUTION
• Pollution of surface water can cause
degradation of ground-water quality and
conversely pollution of ground water can
degrade surface water.
• Eutrophication, accelerated by human activities,
has been determined as the main cause of
impaired surface water quality.
• Agricultural runoff (surface and subsurface) and
erosion from high Phosphorous soils may be
major contributing factors to surface water
eutrophication.
What can you do to help solve
this problem?