State-Level Estimates of Phosphorus and Nitrogen Levels in Wadeable Streams

• Activity Number: 66
• Type: Topic Contributed
• Date/Time: Sunday, July 29, 2012 : 4:00 PM to 5:50 PM
• Sponsor: Section on Survey Research Methods
• Author(s): David Marker*+ and John W Rogers and Rebecca Jeffries Birch and Marla Smith
• Companies: Westat and Westat and Westat and EPA
• Keywords: Small area estimation ; geospatial correlation ; environmental sampling

Abstract

The U.S. Environmental Protection Agency produces national estimates of water quality using data from the National Aquatic Resources Surveys (NARS). The NARS program consists of four surveys conducted on a five-year cycle, each focusing on a different type of water body: lakes, wetlands, coastal waters, and rivers and streams. Individual states are interested in estimating water quality for their state and local areas; however, NARS is not designed to produce design-based estimates at that level of geography. Consequently, EPA is evaluating small area estimation approaches. Westat is assessing supplemental data sources for use with the Wadeable Streams Assessment (WSA) which collected water quality data from 1,400 sites. This presentation will report on progress in identifying data sources on all streams that might be used to produce small area estimates for phosphorus and nitrogen, which are of particular interest in environmental assessments. Different data sources are available at different hierarchical aggregations of streams which create additional complexity to designing approaches for SAE. These data sources will inform what SAE methodologies might be appropriate.