Nonpoint source pollution occurs when runoff from rainfall or snowmelt travels over and/or infiltrates through the ground and picks up contaminants. These contaminants are deposited into streams, lakes, rivers, and ground water.

Nonpoint source pollution is generally associated with human land-disturbing activities such as: 

• Urban development
• Construction
• Agriculture
• Recreation
• Silviculture
• Mineral exploration

Common nonpoint source contaminants include the following:

• Fertilizers and pesticides from agricultural and residential activity
• Oil, grease, and toxic chemicals from urban runoff
• Sediment from construction activity or stream bank erosion
• Bacteria and nutrients from livestock and pet waste, or from failing septic systems

Water quality affects all Wyoming citizens.  In addition to providing safe drinking water, clean water supports agriculture, recreation, and tourism, and is necessary for healthy ecosystems. 

Even if we don’t live next to a stream or river, activities that each of us do can affect water quality.  At any moment, we are each located in a watershed.  A watershed is an area of land that drains to a common point, usually a stream, river, wetland, or lake.  Think of a big bathtub!  Watersheds can be very small, just a few acres, or they can be very large, encompassing a good portion of the state or multiple states, depending on what drainage point you are considering.  Small watersheds make up larger watersheds. 

Runoff from rainfall events or snowmelt travels over and through the land in a watershed.  As it does, it may pick up pollutants that are ultimately deposited into streams, rivers, or lakes within the watershed.  Thus activities that occur throughout the watershed, not only those directly adjacent to waterbodies, can affect the quality of water that we each rely on for drinking water, fishing, boating, agriculture, and many other uses.

Therefore, restoration and protection of our water quality resources is something each citizen can help achieve.  Some restoration and protection projects require extensive planning and coordination between local organizations, private landowners, and government agencies.  However, there are also simple activities that each of us can do to prevent nonpoint source pollution to Wyoming’s streams, lakes and rivers.  Residents should understand that while the actions of a single person may seem insignificant, when combined with similar actions of hundreds or thousands of other residents, the potential to pollute their local waters is very real.  The quart of oil dumped down a storm drain by one person on a given Saturday may be repeated hundreds of times that day.  Thus, while each of the following activities may seem minor, the combined effort of citizens across the state can make a major improvement in our water quality!  

Ten Simple Things You Can Do To Prevent Nonpoint Source Pollution

• Use the minimal amount of fertilizers and pesticides needed for your lawn or garden. Read label directions carefully!  Do not apply pesticides or fertilizers to your lawn or garden before or during rain.
• Consider planting native plant species in your yard that use less water and have fewer or no pesticide and fertilizer requirements. 
• Establish plants on bare areas of your yard to prevent soil erosion.
• Keep lawn clippings, leaves, and other yard waste out of storm drains and gutters.  Compost yard waste and kitchen waste and leave lawn clippings on your lawn.
• Make sure that household chemicals and automotive products such as paints, cleaners, oil, and antifreeze are disposed of properly.  Contact your local government to see if there is a hazardous household waste collection program in your community.  Select less-toxic or non-toxic household cleaners when possible.  
• If caring for livestock on your property, manage animal waste to minimize mixing with stormwater runoff.
• Pick up pet waste.
• Clean up spilled oil, antifreeze and brake fluids.  Never put used oil or other chemicals down storm drains and street gutters—these outlets drain directly to our streams, rivers, and lakes!
• Wash your car on the grass or at a car wash.  Washing your car on the driveway means that soap and dirt will wash into the nearest storm drain.

More ideas on EPA’s Website “What You Can Do To Prevent NPS Pollution”

More ideas on the City of Casper’s Stormwater Management Website

Nonpoint sources of pollution contribute to the majority of Wyoming’s surface water quality impairments. 

The three nonpoint source pollutants causing the majority of Wyoming’s surface water quality impairments are bacterial pathogens, sediment, and selenium.

Bacterial Pathogens

Nonpoint sources of pathogenic bacteria such as Escherichia coli commonly include faulty or inadequate septic systems, livestock operations, pet waste, and wildlife. Exposure to elevated levels of pathogenic bacteria can be a public health safety concern if contaminated water was accidentally ingested during recreation uses of the water body.

Sediment

Eroding stream banks and surface runoff over bare land contribute sediment to Wyoming’s waters. Human land-disturbing activities that can contribute to erosion and sediment transport include:

• Crop production
• Construction
• Roads
• Overgrazing by livestock or wildlife
• Timber harvesting
• Urban development
• Mining

Sediment loading increases turbidity which limits the amount of sunlight reaching aquatic plants and also affects fish spawning grounds and macroinvertebrate communities. In addition, sediment often transports other pollutants, such as phosphorus, nitrogen, pathogens, and heavy metals, which can attach to the sediment particles. 

Selenium

Selenium is an essential trace element to humans and animals, but in higher concentrations can be toxic. Selenium bioaccumulates and can negatively impact fish and waterfowl reproduction. 

Selenium naturally occurs in the soils of several areas of Wyoming, particularly in areas derived from marine shales. Precipitation and irrigation of selenium rich soils can dissolve and mobilize selenium to surface and ground waters. 

Thus, while some sources of selenium occur naturally, anthropogenic activities that can increase selenium loading to surface waters include irrigated agriculture return flow, mining, and oil and gas production.

Riparian areas are the narrow strips of land adjacent to streams, rivers, lakes, ponds, and wetlands.  They are characterized by plant species that are adapted to a wetter environment than plant species that dominate drier, upland environments.  In arid and semi-arid climates, such as Wyoming, riparian areas can usually be clearly distinguished as the green areas adjacent to streams, rivers, and lakes. 

While riparian areas comprise only a very small portion of the land area in the state, they are an extremely important component of healthy watersheds and ecological function.  Riparian areas provide critical habitat for wildlife.  Relating to water quality, the ecological benefits of riparian areas are numerous.  By acting as buffers between upland areas and open water, they help filter pollutants such as nutrients and sediment.  Healthy riparian vegetation helps to reduce stream bank erosion and maintain stable stream channel geomorphology.  Vegetation also provides shade, which works to lower water temperatures.  Lower water temperatures support higher dissolved oxygen levels which are important to maintain fisheries. 

Many land-uses have the potential to negatively affect riparian areas.  Urban development, improper grazing practices, improper timber harvesting practices, and over-use from recreational activities are just a few examples.   Consequently, there are areas in Wyoming where a functional, healthy riparian zone no longer exists.  Streams that were once lined with willows or other riparian species may now only be lined with limited grass or sedges that are not capable of stabilizing stream banks. 

Many local organizations, agencies, and landowners across Wyoming have worked to implement best management practices to restore or protect riparian areas, but many areas remain that need restoration or protection measures.  Activities such as proper grazing management, proper timber harvesting practices, proper planning of urban development, and establishing “no-mow” zones in urban parks all work to protect riparian areas.  Restoring degraded riparian areas may involve a wide variety of best management practices, including planting native species to re-vegetate the area, using natural materials to stabilize stream banks, and reshaping stream channels to restore stable geomorphology. 

Links to more information about Riparian Areas

Wyoming Game and Fish Department Riparian Information