To improve the nation's waters, the U.S. Environmental Protection Agency this week released a new web-based tool, the Causal Analysis/Diagnosis Decision Information System (CADDIS), which simplifies determining the cause of contamination in impaired rivers, streams and estuaries.

More than a thousand U.S. water bodies have been identified as impaired, and in many cases, the cause is unknown. There are many possible sources of pollution such as industrial waste, municipal sewage, agricultural runoff, naturally occurring minerals in rock and sand, and biological materials.

Before restorative or remedial actions can be taken, the cause of impairment must be determined. By helping to find the source of contamination, state and local organizations will be better able to implement the Clean Water Act.

CADDIS provides a standardized and easily accessible system to help scientists find, use and share information to determine the causes of aquatic impairment. Causal analyses look at stressor-response relationships, meaning the effect of a specific substance or activity (stressor) on the environment. Typical water stressors include excess fine sediments, nutrients, or toxic substances.

CADDIS was developed by EPA scientists through partnerships with EPA programs and regions, as well as states and tribes.

The version of CADDIS released this week is the first of three. Future versions will include modules to quantify stressor-response relationships, and databases and syntheses of relevant literature on sediments and toxic metals.

CADDIS is available online.

1/27/2006