Why Does NDEE Conduct Basin Rotation Monitoring?
A goal of the federal Clean Water Act is that each state assess the water quality of “all navigable waters of the State.” In Nebraska, this means assessing nearly 1,000 miles of perennial streams and rivers, and more than 134,000 acres of lakes and reservoirs. These water quality assessments are used to determine if the sampled water bodies are safe for recreation and if they can support aquatic life and industrial or agricultural uses. If the data shows that a waterbody cannot support all of its designated uses due to pollution, NDEE begins a process to determine the source of the pollution and develop a pollution control strategy. This process can be both time consuming and costly, so it is imperative that NDEE has sufficient data about a waterbody before it makes a determination on the water quality. The Basin Rotation Monitoring Program (BRMP) was developed so that NDEE can work towards the goal of assessing all water bodies within the state, while at the same time, ensuring sufficient data is collected to determine if a waterbody is impaired by pollution. By focusing sampling efforts in 1-3 river basins each year for intensive monitoring, NDEE can collect enough water quality samples to perform accurate assessments, while at the same time, collect data from many water bodies because of the reduced size of the sampling area.
Where and When is the Monitoring Done?
Monitoring is done on a six-year rotation in the 13 major river basins in the state. Monitoring in each basin, during its rotation year, is conducted at approximately 40 sites on a weekly basis from May 1 through September 30. The map below shows the basins and their rotation schedule.
NDEE 6-year basin rotation monitoring schedule
How are the Monitoring Sites Chosen?
One of the primary objectives for the BRMP is the protection of public health. To meet this objective, NDEE aims to assess 100% of the stream segments and public lakes that support primary contact recreation (swimming and wading). For this reason, the majority of monitoring sites in this program have been designated for recreation.
What is Monitored?
NDEE monitors a suite of water quality parameters to establish general water quality trends and to ensure each stream is able to support its designated uses. The following parameters are collected at each stream site: ammonia, nitrate-nitrite, kjeldahl nitrogen, total phosphorus, chloride, total suspended solids, stream discharge and atrazine. Water temperature, pH, conductivity, dissolved oxygen, turbidity and E. coli bacteria are collected at both stream and lake sites.
Impairments and Sources
According to the 2018 integrated report, E. coli is the most common water quality impairment. E. coli samples are collected from water bodies used for recreational uses such as swimming and boating. E. coli in surface water can cause gastrointestinal problems if swallowed. E. coli exists naturally in the environment and can become elevated in lakes and rivers from runoff following a rainfall event. A few sources of E. coli include wildlife and livestock feces and failing septic systems. The herbicide atrazine is the second most common impairment detected. Atrazine is a widely used herbicide that is commonly applied in the spring when rain events can cause cropland runoff to enter nearby streams and rivers.
Data from the BRMP are combined with the Ambient Stream, Ambient Lake and other surface water monitoring programs to make up the data package used for all assessments of the status of Nebraska’s waters.
To contact program experts, call (402) 471-4709 or (402) 471-4264.