Revised Methods For Characterizing Stream Habitat In The National Water Quality Assessment Program

Stream habitat is characterized in the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program as part of an integrated physical, chemical, and biological assessment of the Nation's water quality. The goal of stream habitat characterization is to relate habitat to other physical, chemical, and biological factors that describe water-quality conditions. To accomplish this goal, environmental settings are described at sites selected for water-quality assessment. In addition, spatial and temporal patterns in habitat are examined at local, regional, and national scales. This habitat protocol contains updated methods for evaluating habitat in NAWQA Study Units. Revisions are based on lessons learned after 6 years of applying the original NAWQA habitat protocol to NAWQA Study Unit ecological surveys. Similar to the original protocol, these revised methods for evaluating stream habitat are based on a spatially hierarchical framework that incorporates habitat data at basin, segment, reach, and microhabitat scales. This framework provides a basis for national consistency in collection techniques while allowing flexibility in habitat assessment within individual Study Units. Procedures are described for collecting habitat data at basin and segment scales; these procedures include use of geographic information system data bases, topographic maps, and aerial photographs. Data collected at the reach scale include channel, bank, and riparian characteristics.

The U.S. Geological Survey (USGS) established the National Water Quality Assesment (NAWQA) program in 1985 to assess water quality conditions and trends in representative river basins and aquifers across the United States. With this report, the NRC's Water Science and Technology Board has provided advice to USGS regarding NAWQA five separate times as the program evolved from an unfunded concept to a mature and nationally-recognized program in 2002. This report assesses the program's development and representative accomplishments to date and makes recommendations on opportunities to improve NAWQA as it begins its second decade of nationwide monitoring.