In urban areas, stormwater runoff is the leading cause of water pollution. As populations grow and more land is developed, more surfaces are created where water cannot soak in. When it rains, runoff from these surfaces carries leaves, grass clippings, fertilizers, pesticides, oil, pet waste, and other pollutants into storm drains that lead directly to our local waterways.
Many streams and lakes in the Lincoln area are now classified as impaired waterbodies, meaning they fail to meet water quality standards due to the recurring presence of one or more pollutants.
Related: Lincoln Area Impaired Water Bodies Map
Our watershed is an interconnected system of land, water, air, and the life it supports - including you and everyone within your community. Your everyday actions affect our watershed. When a watershed is unhealthy, it becomes a concern for everyone.
The symptoms of an unhealthy watershed are all around us. Fish and other aquatic life populations have declined due to poor water quality in many of our local streams and lakes. Fish consumption advisories warn us of heavy metals in fish and recreational areas are sometimes closed due to bacteria and toxic algal blooms.
While it would be impossible to eliminate all pollutants found in our lakes and streams, we can still make a difference if we work together. Even small actions, like changes to our home and lawn care routines, can contribute to a healthier watershed.
Below is information regarding stormwater pollutants and their impacts on water quality
Conductivity is a measure of how well water can pass an electrical current. It is an indirect measure of the presence of inorganic dissolved solids such as chloride, nitrate, sulfate, phosphate, sodium, magnesium, calcium, iron and aluminum. The presence of these substances increases the conductivity of a body of water.
Inorganic dissolved solids are essential ingredients for aquatic life. They regulate the flow of water in and out of organisms' cells and are building blocks of the molecules necessary for life. A high concentration of dissolved solids, however, can cause water problems for aquatic organisms and also decrease dissolved oxygen levels. The streams in and around Lincoln rate higher on the conductivity scale due to the natural high salinity levels in the local environment. Road salt can also contribute to higher conductivity. In Lincoln, typically only downtown areas, arterial streets and bus routes are salted for winter driving conditions.
Next: Dissolved Oxygen
Oxygen gets into water by diffusion from the surrounding air, by aeration (rapid movement), and as a waste product of photosynthesis. Oxygen is more easily dissolved in cold water.
Adequate dissolved oxygen is necessary for good water quality. Oxygen is a necessary element to all forms of life. Natural stream purification processes require adequate oxygen levels in order to provide for aerobic life forms. As dissolved oxygen levels in water drop, aquatic life is put under stress. The lower the concentration, the greater the stress. Oxygen levels that remain low, even for a few hours, can result in large fish kills.
Adequate dissolved oxygen is necessary for good water quality.
Next: E. coli
E. coli is a type of fecal coliform bacteria commonly found in the intestines of humans and animals (both from pets and wild animals). E. coli is short for Escherichia coli. The presence of E. coli in water is sometimes an indication of sanitary sewage contamination or animal waste. However, we now know E. coli that is not associated with humans or animals can persist in the environment.
During rainfall events, snow melts, irrigation or other types of runoff, E. coli may be washed into local streams and water bodies from animal waste (both domestic and wild) or other sources. Like many bacteria, E. Coli has developed into different strains, some of which are quite harmful. When persons come in to contact with water that is contaminated with a harmful strain of E. coli, they may accidentally ingest the contaminated water and become ill. E. coli is also a source of nutrients for plant life and can lead to an increased likelihood of algal blooms.
More Info: Pet Waste
Pet waste billboard
Previous: Dissolved Oxygen
pH is an important limiting chemical factor for aquatic life. If the water in a stream is too acidic or basic, an imbalance may result and harm or kill stream organisms.
pH is expressed in a scale with ranges from 1 to 14. A solution with a pH less than 7 is considered acidic. A solution with a pH value greater than 7 is considered basic.
Streams generally have a pH values ranging between 6 and 9, depending upon the presence of dissolved substances that come from bedrock, soils and other materials in the watershed.
Changes in pH can change the aspects of water chemistry. For example, as pH increases, smaller amounts of ammonia are needed to reach a level that is toxic to fish. As pH decreases, the concentration of metal may increase because higher acidity increases their ability to be dissolved from sediments into the water.
Streams generally have a pH values ranging between 6 and 9.
Previous: E. coli
High levels of nitrogen and phosphorus in our lakes, rivers, and streams cause the degradation of these water bodies and harm fish and wildlife. This problem is widespread—more than half of the water bodies in the United States are negatively affected in some way by nitrogen and phosphorus pollution.
Nitrogen is important to all life. However, when nitrogen concentrations become excessive and other essential nutrient factors are present, eutrophication (a reduction in dissolved oxygen in water bodies caused by an increase of mineral and organic nutrients) and associated algal blooms can be become a problem.
Phosphorus is a common constituent of fertilizers, manure, organic wastes in sewage, industrial effluent and is typically present in eroded soils. It is an essential element for plant life. However, when there is too much of it in water, it can speed up eutrophication of rivers and lakes.
More Info: Fertilizer
Excessive nitrogen concentrations can lead to an overgrowth of algae.
Sediment is a common pollutant to most local streams and water bodies. Sources of sediment are from stream bank erosion, construction sites, street runoff and other sources. Sediment in streams lowers the oxygen level and clarity of the water, making habitable conditions for aquatic life more difficult or impossible. Sedimentation within streams and water bodies also serve as a storage area for nutrients, E. coli and other pollutants, allowing these pollutants to be re-introduced into the water body during runoff events. Sedimentation takes up storage areas for flood control and can be a hindrance to flow for both public and private (e.g. neighborhood association ponds, detention ponds, private lakes, etc.) waterways.
Nationally, the final settling area for the sediment from all of the tributaries of the Mississippi River (including local streams and water bodies from the Lincoln area) is the Gulf of Mexico. Sediment along with the pollutants attached to the sediment result in an eutrophic area (area with very low oxygen levels) in the gulf called the Dead Zone which is roughly the size of the state of Connecticut. In the Dead Zone there is little or no aquatic life present because of sediment and associated contaminants.
More Info: Sediment and Erosion Control
Turbidity refers to an optical property of liquids that measures the scattering and/or absorption of light due to material suspended in solution. Suspended material includes inorganic and organic solids as well as living organisms. Total Suspended Solids (TSS) is a direct measure of suspended sediment concentration and is usually expressed in milligrams per liter (mg/l).
Soil erosion and sedimentation can contribute to turbid conditions and poor water quality. Turbidity and sediment resuspension have become threats to the environment in many waterways. Erosion is the detachment of soil particles from the land surface by natural forces such as rain and windstorms and by human induced causes. Sedimentation occurs when the eroded soil is deposited by runoff into surface waters such as streams and lakes. Both processes can be greatly accelerated by urban land-use, agriculture, timber harvesting and development.
While the physical impact of soil erosion and sedimentation affects aquatic resources and degrades water quality, the effects are magnified when rural and urban runoff carries contaminants associated with sediments.
Soil erosion and sedimentation can contribute to turbid conditions and poor water quality.