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Watershed Assessment and Management



The Watershed Assessment and Management Section oversees the health of the state’s surface water resources and takes actions to protect and improve water quality for aquatic life and human use.

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Steve Williams
Environmental Program Administrator
302-739-9939

DNREC Water Quality Data Portal How You Can Help

We all live in a watershed. Watersheds are the land areas that drain to water bodies like ponds, streams, estuaries, and oceans. What we do on the land affects the quality of those waters.

To protect water from nonpoint source pollution, it is important to think about management actions to improve water quality on a watershed scale.

Delaware’s Watersheds

Delaware has four larger scale watersheds, or drainage basins. In northern Delaware, water flows through the Piedmont Drainage, which is named after the local geology. Streams and ponds in western Delaware drain to the Chesapeake Bay, while in eastern Delaware they drain to the Delaware Bay. In southeastern Delaware, water flows to the Inland Bays and the Atlantic Ocean.

These larger scale watersheds can be broken down into smaller watersheds, which are named after the main water features within each. There are 45 of these watersheds in Delaware.

Water Quality Standards

To protect the water for plants, animals, and people, Water Quality Standards are set to establish tolerable levels of pollutants.

Each year, this section develops a water quality monitoring plan, which lays out the locations and frequency of sampling and determines the parameters that will be measured in each sample. This data is compared to standards to assess if water quality is good or needs improvement.

These evaluations are presented to the EPA every other year in a two-part document, called a Combined 305 (b) Report and 303 (d) List. The first part of the document is the Watershed Assessment Report, also called a 305(b) Report. The second part of the document contains a list of all the waters in the state that are considered impaired because they do not achieve water quality standards, and is called the 303(d) List.

Total Maximum Daily Loads

When waters are classified as impaired, a Total Maximum Daily Load (TMDL) must be established. TMDLs are regulations that place limits on the amount of a pollutant that can enter a water body from point and nonpoint sources.

Since the late 1980’s, this section has been busy modeling our watersheds to established TMDLs for nitrogen, phosphorus, and bacteria for all of the waters in Delaware impaired by these parameters. To clean up the waters, however, you have to do more than just place a limit on the pollution: you have to take action.

Tributary Action Teams

Delaware’s Tributary Action Teams, or groups of stakeholders, have been working together to recommend a list of actions to reduce nonpoint source pollution in several TMDL watersheds.

These recommendations, which include both voluntary and regulatory actions, are used to develop pollution control strategies. In addition to these documents, other watershed plans and strategies have been developed over the years. Some of the actions to improve water quality are simple things anyone can do.

Watershed Approach to Toxics Assessment and Restoration

Where toxic substances affect Delaware’s water resources, two DNREC divisions have teamed up to work together, on a watershed scale, to address pollution problems.

The Division of Waste and Hazardous Substances and the Division of Watershed Stewardship have developed a Watershed Approach to Toxics Assessment and Restoration (WATAR). WATAR is a holistic (watershed scale), integrated, and systematic approach to the evaluation of contaminant sources, transport pathways, and receptors, and a mechanism to implement restoration actions based upon site prioritization.

Delaware Wetlands

The Watershed Assessment and Management Section houses the Wetland Monitoring and Assessment Program, whose goal is to assess the condition, or health, of wetlands and the functions and ecosystem services that wetlands provide. This information is used to inform the citizens of Delaware and to improve existing education, restoration, protection, and land use planning efforts.

The Delaware Shellfish Program

Because shellfish can become unsafe for human consumption due to high levels of bacteria and viruses, DNREC routinely surveys pollution sources for indicator bacteria levels. Data from sampling stations are analyzed and the information facilitates program operating procedures and health standards that protect shellfish consumers.

Delaware is a member of the National Shellfish Sanitation Program (NSSP), a cooperative of state, federal, and industry representatives responsible for establishing the national guidelines that protect consumer health in all certified state programs. The program is responsible for monitoring and classifying shellfish growing areas to determine if recreational and commercial shellfish harvesting is safe. The program also inspects and ensures certification of all commercial shellfish shippers and processors within the state.

Recreational Water Program

Recreational water quality is regularly monitored at all beach areas guarded by State or local governments in Delaware. The Department tests for Enterococcus bacteria, which indicate the presence of other potentially harmful bacteria and viruses. The results of these tests are available online and though an email alert system.

The state, in conjunction with the University of Delaware’s Citizen Monitoring Program, monitors for the presence of potentially Harmful Algal Blooms (HABS) which could impact our inland and coastal beaches. The Recreational Water Program also monitors for other coastal hazards, such as floatable debris, oil slicks, etc., to further our surveillance and protection of all of the state’s recreational waters.





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