Wood River Valley Aquatic Biology and Habitat Assessment

Science Center Objects

Blaine County’s population nearly quadrupled from about 5,700 to 22,000 people between 1970 and 2010. Residents and resource managers of the Wood River Valley of south-central Idaho are concerned about the potential effects that population growth and the expected increased demand for water might have on the quantity and quality of the valley’s ground and surface waters. Increased water use has the potential to negatively impact streamflow, water quality, and the biological integrity in the Wood River and its tributaries. In the face of current and future stresses on the water resources in the Wood River Valley, a comprehensive assessment of the current condition of the quantity, quality, and aquatic biology of the Wood River and its major tributaries is needed as a means for the establishment of a robust, objective baseline assessment.

The Idaho Department of Environmental Quality has identified suspended sediment, substrate fine sediments, total phosphorus, bacteria, and temperature as pollutants that may degrade or reduce aquatic habitat in the Wood River Valley. Though the USGS has monitored water quality in the area, there has been no comprehensive, long-term water quality and bioassessment (algae, macroinvertebrates, and fish communities) monitoring in the Wood River Valley. These types of assessments are an important piece of trying to understand stream health—the ability of a stream to support aquatic life and the associated beneficial uses.

The USGS measures streamflow conditions at eight sites in the Wood River Valley. In cooperation with Blaine County and non-profit organizations, we will install temperature sensors in May 2014. During summer low-flow conditions, USGS staff will collect algae, macroinvertebrate, and fish community data and associated habitat information from seven representative reaches on the Big Wood River and major tributaries.

We will analyze streamflow, water-quality, habitat and community data, and data from previous studies to a provide resource managers with a baseline of biological conditions and associated habitats. This information can also be used to design a long-term trend monitoring network that will be necessary to identify changes in habitat and biological conditions over time.