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Introduction
The Surface Waters component of EMAP (EMAP-Surface Waters) has responsibility for achieving EMAP goals for the nation's lakes, reservoirs, streams, and rivers. EMAP-Surface Waters' initial efforts emphasized lakes and reservoirs, and this portion of the program is more fully developed than the program for rivers and streams. For lakes and reservoirs a pilot project was conducted from 1991 to 1993 in the Northeast. A stream pilot project began in the mid-Appalachian area in 1993.
In preparing this report the committee relied heavily on two documents: EMAP-Surface Waters Monitoring and Research Strategy - Fiscal Year 1991 and EMAP-Surface Waters 1991 Pilot Report. A subgroup of the committee also met with EMAP-Surface Waters personnel in August 1992 to discuss detailed aspects of EMAP-Surface Waters, and a brief document on the stream survey was supplied to the committee shortly before this report was completed. In addition, a conference call between several committee members and EMAP officials was held in May 1994 to discuss the stream pilot study. Data collected in the field by the technical staff appear to be of high quality. Many of the concerns raised in this report concern the utility of the data and are program-wide issues requiring resolution and guidance at higher levels of EMAP.
Objectives of EMAP-Surface Waters parallel those of the general EMAP program. The Surface Waters objectives (from D. McKenzie, EMAP Program Officer, personal communication February 25, 1994) are to:
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Estimate the current status, trends, and changes in selected indicators of condition of the nation's lakes, reservoirs, streams, and rivers on a regional basis with known confidence.
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Estimate the extent (number and surface area of lakes and reservoirs, miles of rivers and streams) of the nation's lakes, reservoirs, streams, and rivers with known confidence.
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Seek associations between selected indicators of natural and anthropogenic stresses and indicators of the condition of ecological resources.
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Provide annual statistical summaries and periodic assessments on the condition of the nation's lakes, reservoirs, streams, and rivers.
EMAP-Surface Waters differs from most other surface water monitoring approaches and from the National Stream Survey in that it is statistically designed to apply information from a sample of lakes to the entire population of lakes on regional and national scales. According to the EMAP-Surface Waters Monitoring and Research Strategy - Fiscal Year 1991, the EMAP-Surface Waters Design Strategy has the following characteristics that together allow “estimation, with known confidence, of indicators of the ecological condition of regional surface water populations:
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Explicit definition of surface water target populations and their sampling units, and identification of an explicit frame for listing or otherwise identifying all the potential sampling units within each target population.
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Probability sample site selection from the population frame. A uniform grid and cluster sampling will be used to obtain a randomized, systematic sample of surface waters with a geographical distribution reflecting that of the population.
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Representation of ecological conditions in sample lakes and streams using ecological indicators within an index concept.
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Uniform sampling and analytical methods for a suite of response, exposure, and stressor indicator measurement.
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A documented program of rigorous quality control, quality assurance, and quality assessment.” (U.S. EPA, 1991, p. 9).
This NRC report reviews the Surface Waters component of EMAP in the context of the larger program. We pay particular attention to program-wide issues, both strengths and weaknesses, as they apply specifically to EMAP-Surface Waters. These program-wide issues fall into three major classes: assessment end points, indicators, and design. Additionally, as part of the committee's task, this report comments on the Lakes Pilot Project, early information available on the streams program, and on cooperation and coordination with other groups within EMAP as well as other agencies.