Study plan for urban stream indicator sites of the National Water-Quality Assessment Program

Abstract

Urban Indicator Sites are one component of the U.S. Geological Survey’s National WaterQuality Assessment (NAWQA) Program. The objectives of monitoring at the Urban Indicator Sites are to: (1) characterize stream quality from drainage basins with predominantly residential and commercial land use, and (2) determine which selected natural and human factors most strongly affect stream quality. Urban Indicator Sites will be distributed across the United States in settings with statistically different climate and in metropolitan areas that have a population of 250,000 or more. Multiple sites in the same climatic setting will have a range in population density. Ideally, Urban Indicator Sites will monitor drainage basins that have only residential and commercial land use, are 50 square kilometers or larger, are in the same physiographic setting as other Indicator Sites, have sustained flow, and overlap other NAWQA study components. Ideal drainage basins will not have industrial or agricultural land use and will not have point-source-contamination discharges. Stream quality will be characterized by collecting and analyzing samples of streamflow, bed sediment, and tissue of aquatic organisms for selected constituents. Factors affecting stream quality will be determined by statistical analysis of ancillary data associated with Urban Indicator Sites and stream-quality samples. INTRODUCTION The National Water-Quality Assessment (NAWQA) Program is a systematic assessment of the quality of the Nation’s stream and ground-water resources. The U.S. Geological Survey (USGS) implemented the NAWQA program in 1991 to describe the status and trends in the quality of a large, representative part of the Nation’s water resources and to identify the natural and human factors affecting the water quality. Information produced from the NAWQA Program will be useful for policymakers, managers, and the general public at the National, State, and local levels. The basic elements of the NAWQA Program are 59 Study Units that include parts of most of the Nation’s major river basins and aquifers (fig. 1). Study Units Investigations were started between 1991 and 1997. Gilliom and others (1995) discuss the overall design of the NAWQA Program in more detail. The glossary at the front of this report includes brief descriptions for many of the study components and key terms used to describe the NAWQA Program. These study components and key terms are highlighted throughout this report with capital first letters. The emphasis of the NAWQA surface-water design is to monitor the stream quality at Indicator Sites on major streams that drain relatively homogenous land-use and physiographic conditions (Gilliom and others, 1995). Stream quality also is monitored at Integrator Sites on streams that drain mixed land use and at sites on streams that are relatively unaffected by human influences. Streams are monitored for flow, specific conductance, water temperature, and chemical and biological constituents. Urban and agricultural land uses are two of the main land uses being investigated at this time (1997). The objectives of monitoring