Stream quality assessments in the Southeast

Science Center Objects

The South Atlantic Water Science Center is a participant in the Southeast Stream Quality Assessment (SESQA) which covers the southeastern region of the Regional Stream Quality Assessment (RSQA).

The goal of the study is to determine how stream ecology is affected by chemical and physical stressors in small streams? The U.S. Geological Survey (USGS) is addressing this question through studies of relations between stressors and stream ecology across large regions of the United States.

 

Problem Statement:
The U.S. Geological Survey (USGS) National Water-Quality Assessment Program (NAWQA) is assessing stream quality in select ecoregions across the United States. The goals of the Regional Stream Quality Assessment (RSQA) are:

Flow diagram of relationships between watershed stressors and aquatic health

Flow diagram of relationships between watershed stressors and aquatic health(Public domain.)

  1. Characterize multiple water-quality factors—contaminants, nutrients, sediment, and streamflow alterations that are stressors to aquatic life— and ecological conditions in streams throughout the region.
  2. Determine the effects of these stressors on aquatic organisms in the streams. Findings will provide communities and policymakers with useful information on which human and environmental factors are the most critical in controlling stream quality.

Objectives: For 100-150 perennial (year-round) streams in each study region, RSQA projects:

  1. Assess the status of ecological conditions; the geographic distribution of spring-summer seasonal concentrations of contaminants, nutrients, and sediment; and the toxicity of water and sediment.
  2. Assess relations among concentrations of contaminants, nutrients, and sediment; toxicity of water and sediment; and ecological conditions in the sampled streams.
  3. Identify and evaluate statistically the natural and anthropogenic factors in the watersheds affecting concentrations of contaminants, nutrients, and sediment, and ecological conditions in sampled streams.
  4. Develop models to predict concentrations of contaminants, nutrients, and sediment, and, if possible, ecological conditions in the region on the basis of findings from objectives 2 and 3.
Maps of Midwest and Southeast study regions

Maps of Midwest and Southeast study regions(Public domain.)

Approach: Ecological Condition—Algae, benthic invertebrates, and fish com­munities are sampled, along with physical habitat.

  • Water Sampling—Depth/Width-integrating methods are used to sample surface water weekly at each site for up to 10 weeks preceding ecological sampling, to assess temporal variations in-stream water-quality stressors.
  • Integrated Samplers—Passive POCIS sam­plers are deployed to provide temporally-integrated assessment of water-quality stressors.
  • Sediment Sampling—Streambed sediment is sampled coincident with the ecological sampling, to assess sediment-quality stressors.
  • Toxicity Testing—Whole-sediment toxicity tests are conducted with amphipod crustaceans (Hyalella azteca 28-day exposures), midge larvae (Chironomus dilutus 10-day exposures) and freshwater mussels (Lampsilis siliquoidea 28-day exposures), to measure potential effects of contaminants on survival and growth.
  • Continuous Monitoring—Continuous water-quality monitoring is employed at select sites across the region.
  • Daily Pesticide Sampling—Small-volume automated pesticide samplers are deployed in select streams to assess temporal variations in pesticides and pesticide degradation products.