Why Does NDEQ 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 20,000 miles of streams and rivers, and almost 300,000 acres of lakes and reservoirs. These water quality assessments are used to determine if the sampled waterbodies 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, NDEQ 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 NDEQ has sufficient data on a waterbody before it makes a determination on the water quality. The basin rotation program was developed so that NDEQ can work towards the goal of assessing all waterbodies within the state, while at the same time, insuring sufficient data is collected to determine if a waterbody is impaired by pollution. By focusing sampling efforts to a few adjacent river basins each year, NDEQ can collect enough water quality samples to perform accurate assessments, while at the same time, collect data from many waterbodies 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 done on a weekly basis from May 1st through September 30th. In 2010, a total of 32 streams and 17 lakes were sampled from the Elkhorn and Missouri tributaries river basins, resulting in ~1078 water quality samples being collected. The map below shows the basins and their rotation schedule.
How are the Monitoring Sites Chosen?
One of the primary objectives for the Basin Rotation Program is the protection of public health. To meet this objective NDEQ, 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?
NDEQ 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 physical and chemical parameters are collected at each site: ammonia, nitrate-nitrite, total nitrogen, total phosphorus, total chlorides, total suspended solids, turbidity, pH, temperature, conductivity, dissolved oxygen, E. coli bacteria, and pesticides.
Impairments and Sources
The most common impairment detected by NDEQ’s basin rotation monitoring program is the bacteria E. coli. Potential sources of bacterial pollution are improperly functioning waste water treatment facilities, septic tanks, and lagoons, as well as, urban and agricultural runoff.
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.
For more information on the quality of Nebraska’s streams, the most recent Surface Water Integrated Reports can be found on this web site at :http://deq.ne.gov/NDEQProg.nsf/OnWeb/TMDL