Water-Quality and Biological Trends on the
Lower Boise River

---

Status: Active

In 1994, in cooperation with the Lower Boise Watershed Council (LBWC) and Idaho Department of Environmental Quality (IDEQ), the U.S. Geological Survey (USGS) began a comprehensive study of water quality and biotic integrity of the lower Boise River.

Lower Boise water-quality parameters are measured monthly or bi-monthly at 4 mainstem sites and intermittently in its tributaries since 1994. Biological parameters are collected at 5 mainstem sites once a year at low flow.

In 1998, in response to the Clean Water Act requirements, the IDEQ used this data to develop Total Maximum Daily Loads (TMDLs) for three segments of the river. (Occasionally, the sample location and frequency were altered to meet TMDL objectives.) The TMDL specifies the lower Boise River beneficial uses are recreation and cold-water fisheries. Understanding water quality and how it relates to the biological communities is critical for effective land and water management.