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Inland Bays, Delaware - Nonpoint Source Success Story

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Delaware Inland Bays

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SnapshotInland Bays watershed map

The Inland Bays Watershed in Delaware is composed of the Indian River, Indian River Bay, Rehoboth Bay, and the Little Assawoman Bay, which os located in the southwestern part of the state in Sussex County. The watershed contains approximately 32 square miles of water area and drains a land area of about 320 square miles. The health and water quality of the Inland Bays is of great concern to the community, as the bays generate a great amount of income from tourism, real estate sales and recreation.

Due to urbanization, agricultural activities, and low flushing rates, the Bays have become highly enriched with nitrogen and phosphorus. While these nutrients are essential for plant and animals growth , when present in excessive amounts, water quality can deteriorate as aquatic plant growth accelerates and the level of oxygen is reduced. In December 1998, the Delaware Department of Natural Resources and Environmental Control promulgated Total Maximum Daily Loads (TMDLs) for nitrogen and phosphorus for the Indian River, Indian River Bay, and Rehoboth Bay. A TMDL was promulgated for the Little Assawoman Bay in December 2004. To meet the load reductions required by the TMDLs, water quality goals include the elimination of all point sources if nutrient loading to the water bodies, along with a 40% reduction in nonpoint phosphorus loading in the Indian River Bay., Rehoboth Bay and Little Assawoman Bay, 1 65% reduction in the upper Indian Rover Watershed, a 40% reduction of nonpoint nitrogen loading in the Indian River Bay, Rehoboth Bay and Little Assawoman Bay, and an 85% reduction in the upper Indian River Watershed.

Public Talk - Real ChoicesLittle Assawoman Bay

In order to achieve the water quality goals, a Pollution Control Strategy (PCS) was developed by the Inland Bay Tributary Action Team, a group of dedicated residents with varying interests, along with local government representatives, who brought diverse issues to the planning process. Given the large reductions needed in nonpoint source pollutants and their impact on everyone in the community if the reductions are achieved, the Department placed a large emphasis on putting the public first in policy-making. Thus, the Tributary Action Team used a process called "Public Talk--Real Choices" to develop their recommended Pollution Control Strategy. The Strategy is based on general principles developed by the public during the seven public forums held within the Watershed. These principles are the foundation that the Team used in building their Strategy.

Agricultural Pollution Control Strategy

While the team was deliberating their Strategy, the agricultural community was meeting and crafting what became Delaware's Nutrient Management Act. Thus, the Team took agriculture off the table with the understanding that it would be included in the final Strategy at a later date. The Department then convened an Agricultural Pollution Control Strategy workshop, with representatives from the Department, the Nutrient Management Commission, the University of Delaware, USDA-Natural Resource Conservation Service, and Conservation Districts, which recommended best management practices and their nutrient reduction efficiencies to the Secretaries of the departments of Natural Resources and Environmental Control and Agriculture for use in policy formation. The Nutrient Management Commission, created by the Nutrient Management Act to oversee implementation of the law, also endorsed the workgroup's products.  In addition, the Commission endorsed the concept of numerical targets for implementation of agricultural best management practices (BMPs) in the Strategy.  Thus, the final Strategy will include the Team's recommendation for reducing runoff from urban and residential lands as well as from agriculture.

ImplementationDead End Canal

A holding tank compliance program, which was funded by the General Assembly and Sussex County in its first year and now by EPA, was instituted in the watershed.  This program helped bring the compliance rate from 51% to 92% in the first year. Also, a pilot onsite wastewater and disposal systems (OWTDS) compliance program was established. Funding was gained from the 6217 (Coastal Nonpoint Source) Program and the Section 319 Nonpoint Source Program. Of the 94 systems inspected in 2003, 75 needed a pump-out. Permits require a pump-out every three years or when solids fill more than one-third of the tank.  In addition, Delaware's Sediment and Stormwater regulations are now being revised to prefer "green technologies" which will assist in achieving the TMDLs. To date, 114 stormwater BMPs have been implemented resulting in a total nitrogen reduction of 21.85 lbs/day and a total phosphorus reduction of 1.49 lbs/day at an annual cost of $938,698. To enhance community outreach and education about OWTDS pump-outs and proper lawn fertilization, the Team produced two public service announcements which are still being run on a local television station.


A preliminary analysis done to predict progress from the baseline period of the TMDL suggests that changes in agricultural practices and conversion of onsite wastewater systems to central sewer had done the most to reduce nonpoint source nitrogen and phosphorus from entering the Inland Bays. Some examples of the installed agricultural BMPs include liquid waste management, animal waste storage, manure relocation, buffers, grass filter strips, cover crops, and water control structures. Significant reductions were also shown through the removal of over 16,000 septic systems and conversion to central sewer systems. This resulted in a nitrogen reduction of 364.2 lbs/day and a phosphorus reduction of 15.8 lbs.day at a cost of $9,060 per septic system.

During the baseline period of the analysis (1988 through 1990), thirteen municipal and industrial wastewater treatment plants were discharging to the waters of the Indian Bay River, Rehoboth Bay, and their tributaries. Since 1990, six facilities in the Inland Bays sub-basin have effectively eliminated their surface discharge: Delaware Seashore State Park, Frankford Elementary School, Colonial East Mobile Home Park, Townsends, Inc., Pinnacle Foods (Vlasic Foods International), and the Delaware State Housing Authority.  This has led to a reduction of 340 pounds of nutrient per day.

Marsh Fringe

Cumulative efforts has already resulted in a 26% reduction of total nitrogen for the TMDL, and a 64% phosphorus reduction from nonpoint sources toward achieving the TMDL. Further successful implementation of the PCS can occur with the cooperation and support of the community. The Tributary Action Team, working with the Department and local government, recommended a Strategy which can achieve the pollution reduction levels required to achieve water quality goals. Although the plan will be costly and will require many changes on the individual, government, and business levels, the community is willing to step up to the plate and do its part.

Mid-Atlantic Nonpoint Source Pollution Initiative

EPA Region 3
Philadelphia, PA 19103
May 2005

For more information on nonpoint source pollution, TMDLs and restoration practices, please check out EPA's Region 3 Nonpoint Source Program web page.

Partnerships and Coordination
Contact Information

Joshua C. Thompson (joshthompson@inlandbays.com)
Center for the Inland Bays Exit EPA Click for Disclaimer
467 Highway One
Lewes, DE 19958

Katherine E. Bunting-Howarth, J.D., Ph.D. (katherine.howarth@state.de.us)
Delaware Department of Natural Resources and Environmental Control Exit EPA Click for Disclaimer
Division of Water Resources
89 Kings Hwy
Dover, DE 19910

Fred Suffian (suffian.fred@epa.gov)
U.S. EPA Region 3
1650 Arch Street
Philadelphia, PA 19103

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