Idaho DEQ (2014) Nitrate Priority Areas w/Monitoring Wells

Areas with Elevated Nitrate in Ground Water Thirty-four areas in Idaho have been identified as nitrate priority areas (NPAs) with elevated levels of nitrate in ground water, according to a study prepared by the Idaho Department of Environmental Quality (DEQ). Nitrate is a chemical form of nitrogen found in soil and water. In elevated levels, nitrates can present a risk to human health. NPAs are areas where 25% of the sampled wells contain water with nitrate levels of 5 milligrams per liter (mg/L) or greater. The drinking water standard is 10 mg/L. DEQ conducted the study in conjunction with the Idaho Ground Water Monitoring Technical Committee, a panel of scientists from state and federal agencies, universities, and health districts. The 2014 Nitrate Priority Area Delineation and Ranking Process document ranks the 34 areas based on the following three primary criteria: • the number of people living in an area that are potentially drinking nitrate-degraded water • the percentage of sampled wells with elevated ground water nitrate concentrations • water quality trends indicating whether nitrate levels are increasing, staying the same, or decreasing. The potential impact of nitrate on other beneficial uses of ground water besides water supply was also considered. The NPAs are located across Idaho, primarily along the Snake River Plain. The top ten NPAs are Marsh Creek (formerly Cassia County), Weiser, Lindsay Creek, Ada/Canyon, Fort Hall, Blackfoot, Grand View, Bruneau, NE Star, and Black Cliffs. The study consisted of compiling data from over 10,000 wells statewide. Of these, over 4,000 are located within the boundaries of the NPAs. Approximately 400,000 people are estimated to live within the NPAs. The document, which contains a complete listing of all 34 NPAs, can be accessed on DEQ's website (download at right). Also available online is a summary of comments received on the document during a 60-day public comment period and DEQ responses. The nitrate priority area ranking is used to prioritize the development and implementation of strategies to help reduce nitrate loading from land-use activities. In coordination with other agencies, DEQ assists local ground water quality advisory groups in developing ground water quality management strategies for NPAs. 2020 Nitrate Priority Online Map Application (ArcGIS Server 11.0) Idaho DEQ Nitrate in Ground Water Idaho DEQ GIS Open Data Downloads (including Nitrate Priority Areas (2020))