Local Water Quality Assessment
Assessment and reporting of Nebraska's stream water quality is performed by the Water Quality Division of the Nebraska Department of Environmental Quality (NDEQ). Teams of biologists and environmental specialists measure water quality and habitat information on-site; collect waters samples for laboratory analysis; and collect benthic macroinvertebrate and fish from streams and lakes throughout the state. Every two years, NDEQ publishes a report documenting the status and trends of existing water quality for all waters of the state. The latest report is the 2010 Surface Water Quality Integrated Report . See an impairment map of local water bodies based on the 2010 Integrated Report.
As required by the Federal Clean Water Act and by state regulations, the City of Lincoln is required to reduce pollutants to the maximum extent practicable. For a more detailed description of these efforts see the City's current stormwater permit (487 K) .
Natural ammonia is formed when manure, plants and animals break down. Ammonia is a waste product of almost every other life process. From urban sources, this process might originate from domestic animals (e.g. dogs, cats), wildlife (e.g. raccoons, opossums), animals in zoos, horses at racing tracks, and bacteria, etc. Other sources may include sanitary sewer line breaks or inadequately treated sewage.
Ammonia is a source of much needed nitrogen for plants and animals. But when too much material is available to break down, especially in streams and other waterbodies, levels may reach toxic proportions for aquatic life. Ammonia can cause algae in the receiving stream to grow rapidly. Oxygen is then consumed by bacteria that eat the algae, leading to a deterioration of water quality due to low oxygen content in the water. This is harmful and can be fatal to fish and other aquatic life.
Atrazine is used extensively in the United States, Canada and other countries for the control of weeds in agricultural crops, especially in crops such as corn, sorghum, wheat and soybeans. It is one of the most heavily used pesticides in North America, generally being among the top few in terms of total pounds of herbicide used.
Because of its chemical properties and widespread use as a herbicide, concerns have been raised over the risks it poses for both freshwater and saltwater organisms. Atrazine has commonly been detected in surface waters of agricultural watersheds where it has been used. Due to its relative mobility from soil, atrazine surface water concentrations are highest in field runoff, with concentration peaks generally following early major storm events that occur within a few weeks of application.
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.
Some examples of how copper may be released into the environment are through copper mining activities, agricultural activities (e.g., through its use as a mildewcide, fungicide, and/or algaecide), and manufacturing activities (e.g., manufacturing of leather and leather products, fabricated metal products, electrical equipment, and automobile brake pads). Copper may also enter the environment through natural processes; some examples include volcanic eruptions, windblown dusts, decaying vegetation, forest fires and corrosion of copper plumbing.
Elevated levels of copper are toxic in aquatic environments and may adversely affect fish and other aquatic life. Acute toxic effects may be fatal.
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.
E. coli is a type of fecal coliform bacteria commonly found in the intestines of animals (both from pets and wild animals) and humans. E. coli is short for Escherichia coli. The presence of E. coli in water is a strong indication of sanitary sewage contamination or animal waste. Sewage may contain many types of disease-causing organisms.
During rainfalls, 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), leaking sanitary sewers 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 E. coli, they may accidentally ingest the contaminated water with only a small amount of E. coli necessary to become ill. E. coli is also a source of nutrients for plant life and can lead to an increased likelihood of algae blooms. If you have questions regarding pet waste issues, please call Animal Control at 402-441-7900.
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.
High levels of nitrogen and phosphorus in our lakes, rivers, streams, and drinking water sources cause the degradation of these water bodies and harm fish, wildlife, and human health. 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 agricultural 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.
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.
Selenium is a naturally occurring element that is nutritionally essential, but it can be toxic to aquatic life (such as fish and invertebrates) where concentrations are excessive. It is also toxic to cormorants and other birds that consume aquatic organisms containing excessive levels of selenium.
Being a natural element, selenium can be found throughout the environment. Toxic levels of selenium in water bodies have mostly been related to irrigation of western soils that are naturally high in selenium, ash pond discharges from coal-fired power plants using coal that has selenium in it, petroleum refinery effluents, and runoff or discharges from certain mining activities.
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 wind storms 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.