Aquatic Habitat Analysis as an Element of Water Resources Planning and Management

With increased emphasis on environmental quality objectives in water resources planning and management, past practices of simply considering water quality as the only environmental quality objective are inappropriate. Expanded environmental quality objectives include maintenance of high quality aquatic habitat. Water resource systems must provide both physical and chemical conditions appropriate for the propagation and maintenance of healthy diverse aquatic communities. Managing water resources to provide high quality habitat involves planning to meet both water quality and water quantity objectives. Existing technology based water quality controls and stream based water quality criteria can now be supplemented by aquatic habitat management. An approach to aquatic habitat management is illustrated by use of the Incremental Methodology developed by the U. S. Fish and Wildlife Service. The Incremental Methodology uses measures of aquatic habitat to assess instream flows required for by aquatic life. Thus the range of environmental quality objectives in resources planning and management is expanded by application of these methods to include aquatic habitat as well as water quality management. Methods used to determine instream flow needs for rivers in Illinois are reviewed, and the use of this information in developing regulations limiting water extraction for off stream use are described. Aquatic habitat based management is shown to provide workable methods to meet expanded environmental quality objectives in water resources planning and management.