Effects of Nutrient Enrichment

Nutrients, especially nitrogen and phosphorus, are essential for the healthy growth of plants and animals. However, when excessive amounts of nutrients are introduced into streams problems arise. In 1996, the U.S. Environmental Protection Agency’s (USEPA) National Water Quality Inventory listed excessive nutrients in streams as the second main cause of impairment in streams. To protect the aquatic health of streams the USEPA set forth Nutrient Criteria for nutrients, algal biomass, and turbidity. States have until 2007 to adopt the Nutrient Criteria or develop their own Criteria based upon the best data available.

A pool of water in Eagan Ditch.

NAWQA Nutrient Enrichment Study

Nutrient enrichment is one of five national priority topics for the NAWQA Program in the second decade of sampling. The WHMI study unit is part of a national study to analyze the relation between nutrient concentrations, algal biomass, and biological communities. Twenty-eight sites were sampled in 2004. Click here for a USGS fact sheet that describes the NAWQA Nutrient Enrichment Study.

A map of the WHMI displaying basins, sites, and nutrient ecoregions.

State of Indiana Nutrient Enrichment Study

The State of Indiana has made nutrient enrichment a research priority. A spinoff project between the Indiana Department of Environmental Management (IDEM) and the WHMI study began in 2001; eventually about 300 sites will be sampled throughout the entire State of Indiana. For this study, IDEM collects nutrient and other water-chemistry, habitat, fish- and invertebrate-community data. The USGS collects algal biomass (chlorophyll a and ash-free-dry-mass) in benthic and sestonic algae at the same time the nutrients are collected. The goal is to find the relation between nutrients and algal biomass and biological communities. To download an Excel file with algal biomass data for each year click on the links below.

Available datasets:

A map of the WHMI displaying basins, sites, and nutrient ecoregions.