State of the Beach/State Reports/DE/Water Quality

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Delaware Ratings
Indicator Type Information Status
Beach Access77
Water Quality89
Beach Erosion7-
Erosion Response-5
Beach Fill7-
Shoreline Structures6 3
Beach Ecology6-
Surfing Areas45
Coastal Development{{{19}}}{{{20}}}
Sea Level Rise{{{21}}}{{{22}}}

Water Quality Monitoring Program

The Beaches Environmental Assessment and Coastal Health Act (BEACH Act) signed into law on October 10, 2000, amends the federal Clean Water Act (CWA), incorporating provisions intended to reduce the risk of illness to users of the Nation's recreational waters. The BEACH Act authorizes the U.S. Environmental Protection Agency (EPA) to award program development and implementation grants to eligible States, Territories, Tribes, and local governments to support microbiological testing and monitoring of coastal recreation waters, including the Great Lakes, that are adjacent to beaches or similar points of access used by the public. BEACH Act grants also provide support for development and implementation of programs to notify the public of the potential exposure to disease-causing microorganisms in coastal recreation waters. EPA encourages coastal States and Territories to apply for BEACH Act Grants for Program Implementation (referred to as Implementation Grants) to implement effective and comprehensive coastal recreation water monitoring and public notification programs. CWA section 406(i) authorizes appropriations of up to $30 million per year to develop and implement beach programs. Unfortunately, only about one-third that amount has been authorized each year since the program's inception. In recent years, the total funding available for BEACH Act grants has been about $9.5 million. Funding beyond 2012 has been in jeopardy, since EPA's budget requests for this program in FY2013 and FY2014 were ZERO (money for testing in 2013 and 2014 was ultimately allocated as part of Continuing Resolutions to resolve the Federal Budget impasse) and there was also no money for beach testing in the FY2015 budget. Again, it was restored at the last minute as part of a Continuing Resolution. It is very discouraging to have to fight for this basic funding to protect the public's health at the beach every year. Thankfully, there is a growing movement to provide stable funding. Unfortunately, in 2017 the situation is even more dire. If available, funds are allocated to the states and territories based on a formula which uses three factors that are readily available and verifiable: (1) Length of beach season, (2) miles of beach and (3) number of people that use the beaches. Delaware was eligible for a $201,000 grant in fiscal year 2016. The full cost of Delaware’s coastal beach monitoring and notification program is approximately double the amount of the BEACH Act grant.

Portions of the following discussion were taken from NRDC's report Testing the Waters, A Guide to Water Quality at Vacation Beaches, June 2014. NRDC's report evaluates beach monitoring data relative to EPA's recommended Beach Action Value (BAV). The BAV is a more protective threshold than the national allowable bacteria levels used in previous years to trigger beach advisories. The EPA considers the BAV to be a "conservative, precautionary tool for making beach notification decisions."

NRDC ranked Delaware 1st in Beachwater Quality (out of 30 states). 3% of samples exceeded EPA's new BAV standards for designated beach areas.

Delaware has 50 miles of Delaware Bay coastline, 25 miles of Atlantic Ocean coastline, and 115 miles of inland shoreline along Rehoboth Bay, Indian River Bay, and Little Assawoman Bay. The state's marine beach water monitoring program is administered by the Delaware Department of Natural Resources and Environmental Control (DNREC). In addition to testing for enterococcus bacteria, DNREC also tests for harmful algal blooms of the species Karenia brevis and K. papilionacea. The monitoring season in Delaware runs from mid-May to Labor Day. DNREC posts beach closing and advisory information on its website.

Water Quality Challenges and Improvements

Leadership in Water Quality Monitoring

Delaware has a long-standing commitment to informing beachgoers about water quality and has sampled beaches since 1979. DNREC's comprehensive program currently includes sampling for enterococcus bacteria, monitoring for rainfall and other factors known to impact water quality, and surveying the shoreline weekly. Additionally, the state's Floatables and Debris Program has a vessel in the water year-round in all weather to monitor floating debris as well as oil spills, harmful algae blooms, sewage treatment discharges, nutrient runoff, and industrial discharges.

Addressing Pollution Sources

In conjunction with the University of Delaware Sea Grant, DNREC is conducting a source tracking study at designated recreational beaches. In 2012, studies began for certain marine beaches and continued through 2013. One source tracking study was recently completed at a non-beach site in the Delaware Inland Bays to identify the source of high bacteria levels. It was determined that the bacteria originated from shorebirds that use the site to feed and nest nearby. Officials plan to complete the current source tracking study before the 2014 beach season.

Cape Henlopen State Park relies on sewage collection and treatment systems to manage wastewater from cabins, camp sites, beach bath houses, and other facilities. The infrastructure was originally installed in 1914 during Cape Henlopen’s tenure as a military fort. With infrastructure this old the need for extensive repair and replacement is no surprise. The Delaware Department of Parks and Recreation utilized the Delaware Clean Water State Revolving Fund to replace more than 6,200 feet of cracked sewer pipes leading to the park’s treatment system. The pipes were allowing groundwater and stormwater to infiltrate the lines, forcing pumps to work overtime to treat excess flow, and increasing the risk of system failure. The project is yielding impressive results. In April of 2015 the treatment system processed 74,000 gallons of wastewater compared to 1 million gallons in April of 2014.

Green Infrastructure

Delaware's coastal beaches historically have very clean water, due to efforts over 30 years to prevent point and non-point pollution. In 2012, the state continued its efforts to ensure clean water by adopting the Inland Bays Pollution Control Strategy and accompanying regulations for the Indian River, Indian River Bay, Rehoboth Bay, and Little Assawoman Bay watersheds. Contaminants in these bays come from many sources in the watershed, including failing septic systems, residential and agricultural runoff, and wildlife. Additionally, the sewage treatment plants in Lewes and Rehoboth discharge treated effluent into the Lewes and Rehoboth Canal, which feeds into the bays. Poor flushing of the shallow waters in these bays allows pollutants to linger; it can take more than two months for water to move through. The new plan aims to improve water quality through upgrading or replacing residential septic systems and reducing stormwater runoff and pollution from other non-point sources.

Closings and Advisories

DNA analyses to track the source of bacteria at Slaughter Beach and Prime Hook Beach have shown that nonhuman sources contribute to indicator bacteria counts at these beaches. Monitoring results at these beaches are adjusted downward to account for nonhuman sources at these beaches before the water quality standard is applied. (Monitoring data are reported before this adjustment is made, and NRDC uses the unadjusted values in its analysis of exceedances.) For Slaughter Beach, the correction factor is 0.49 (which is multiplied by the raw count). This was calculated on the basis of a microbial source tracking study at this beach that found that 77% of fecal bacteria came from wildlife sources, with a 26% margin of error. At Prime Hook, microbial source tracking found that 70% of fecal bacteria came from wildlife, with a 24% margin of error, resulting in a correction factor of 0.54 for this beach.

Delaware has a standard for issuing preemptive rainfall advisories. For marine waters, the DNREC has determined that 3.5 inches of rainfall within 24 hours or 3 inches within 12 hours may trigger a closing. Preemptive closings are issued in the case of a known sewage spill.

The DNREC samples water and/or shellfish for harmful algal bloom species and toxins and issues swimming advisories at freshwater beaches because of harmful algal blooms. The state discovered its first known occurrence of a Karenia brevis bloom during routine beach observations in late August of 2007. The toxins produced by this species of harmful algae can aerosolize and cause respiratory symptoms. Because of the 2007 K. brevis bloom, Delaware enhanced its surveillance analysis, response, and public notification capability for marine toxins and harmful algal blooms in 2008. The DNREC’s Comprehensive Algal Bloom Monitoring Program was implemented in cooperation with the University of Delaware Sea Grant Marine Advisory Service. This included follow-up monitoring of harmful algal blooms at the Indian River Inlet, a beach site that is used by surfers. The recreational water program also provided funding for university research into identifying harmful algal bloom species. Here are the latest reports.

The News Journal in Wilmington, Delaware reported in March 2008 that scientists from the University of North Carolina at Wilmington had verified cells of Karenia brevis in water samples taken from near Rehoboth Bay. “The farthest north Karenia brevis has ever been reported previously is North Carolina,” said Dr. Patricia A. Tester, branch chief in the Center for Coastal Fisheries and Habitat Research at NOAA-National Ocean Service.

The impetus for Delaware's harmful algal bloom monitoring program came from observations of 10 separate fish kills in Delaware's inland bays from July through August 2000 by DNREC staff and local boaters, including members of Surfrider Foundation's Delaware Chapter. An article published in Environmental Health Perspectives in May 2002 discussed water quality investigations in the vicinity of Bald Eagle Creek, Rehoboth Bay that were conducted following the large fish mortality events. From the article's abstract:

Microscopic examination of samples from the fish kill site revealed the presence of a single-cell Raphidophyte alga Chattonella cf. verruculosa at a maximum density of 1.04 × 107 cells/L. Naturally occurring brevetoxins were also detected in the bloom samples. Besides the Chattonella species, no other known brevetoxin-producing phytoplankton were present. Chromatographic, immunochemical, and spectroscopic analyses confirmed the presence of brevetoxin PbTx-2, and PbTx-3 and -9 were confirmed by chromatographic and immunochemical analyses. This is the first confirmed report in the United States of brevetoxins associated with an indigenous bloom in temperate Atlantic estuarine waters and of C. cf. verruculosa as a resident toxic organism implicated in fish kills in this area. The bloom of Chattonella continued throughout September and eventually declined in October. By the end of October C. cf. verruculosa was no longer seen, nor was toxin measurable in the surface waters. The results affirm that to avoid deleterious impacts on human and ecosystem health, increased monitoring is needed for brevetoxins and organism(s) producing them, even in areas previously thought to be unaffected.

DNREC monitors all 25 miles of open ocean coast, plus 25 miles of bay coastline, from Cape Henlopen north to Slaughter Beach. Open ocean beaches that are routinely monitored are:

  • Cape Henlopen State Park
  • Beach near Gordon's Pond
  • Rehoboth Beach — Virginia Avenue
  • Rehoboth Beach — Rehoboth Avenue
  • Rehoboth Beach — Queen Street
  • Dewey Beach
  • Tower Road — Ocean Beach
  • North Indian River Inlet Beach (Surfing Beach)
  • South Indian River Inlet Beach
  • Bethany Beach
  • South Bethany Beach
  • Fenwick Island State Park Beach
  • Delaware/Maryland Line Beach

See a map with the current list of monitored beaches here. Click on the map to get information regarding each beach.

The DNREC also provides an advisory information line during the summer at 1-800-922-WAVE.

Other Water Quality Monitoring Programs

National Ocean Service/National Center for Coastal Ocean Science (NCCOS) has carried out many water quality research projects in Delaware.

Water Quality Contacts

Kathy Bunting-Howarth, Director of Water Resources
Department of Natural Resources and Environmental Control

Debbie Rouse
Environmental Scientist
Recreational Water Program
Delaware Department of Natural Resources and Environmental Control
820 Silver Lake Plaza – Suite 220
Dover, DE 19904
Phone: 302-739-9939
Beach Hotline: 1-800-922-WAVE

Michael Bott
Environmental Scientist
Recreational Water Program
Delaware Department of Natural Resources and Environmental Control
820 Silver Lake Plaza – Suite 220
Dover, DE 19904

Beach Closures

NRDC reported:

In 2013, Delaware reported 24 coastal beaches. Of all reported beach monitoring samples, 3% exceeded the Beach Action Value (BAV) of 60 enterococcus bacteria colony forming units (cfu) per 100 ml marine or estuarine water in a single sample. NRDC considers all reported samples individually (without averaging) when calculating the percent exceedance rates in this analysis. This includes duplicate samples and reported samples taken outside the official beach season, if any.

The beaches with the highest percent exceedance rates of the BAV in 2013 were Rehoboth-Virginia Ave. Beach in Sussex County (11%), Deauville Beach in Sussex County (11%), Slaughter Beach (Bay Beach) in Sussex County (8%), and Broadkill Beach in Sussex County (6%).

For a bar chart showing a 5-year water quality trend, see NRDC's report.

In June 2011 an article was posted at titled Ocean water is constantly tested that explained the beach water testing program for ocean beaches in Delaware and Maryland. In this case, "constantly" means once or twice per week from Memorial Day to late September.

The University of Delaware College of Earth, Ocean, and Environment has conducted research at areas (such as the Inland Bays) that have chronic postings.

DNREC keeps historical records (since 1989) and identifies areas with chronic posting or closures. This information is available to the public. According to DNREC, these closures include closure dates for pond, lake and bay beaches as well as ocean beaches. Most beach closures affect inland bodies of water (ponds and lakes) and not ocean beaches.[1]

In June 2013, U.S. EPA released its latest data about beach closings and advisories for the 2012 swimming season. Note that for some states the data is incomplete, making state-to-state or year-to-year comparisons difficult. Here's EPA's BEACH Report for Delaware's 2012 Swimming Season. EPA no longer publishes this report.

The EPA has published information on water quality in Delaware, including Delaware Inland Bays and Delaware Estuary.

Another EPA water quality website with information on Delaware is Mid-Atlantic Coastal Environment.

The United States Geological Survey maintains a website, USGS Water Resources of Maryland, Delaware, and the District of Columbia. This site is a valuable source of information including current projects, online reports, publications, and maps, real-time water conditions and educational outreach material for teachers and students:

Delaware Sea Grant also has some information on ocean water quality.

Storm Drains and Sewage Outfalls

DNREC staff reports that a single sewage treatment plant (STP) outfall exists along the Delaware Atlantic Ocean coast. South Coastal STP discharges approximately 5 million gallons of effluent per day 1.2 miles (6,670 feet) off of South Bethany in about 60 feet of water. The outfall location is 38° 31' 34" N, 75° 01' 56" W.

There is a proposal to pump up to 3.4 million gallons per day of treated sewage from Rehoboth Beach through a 6,000-foot outfall pipe into the Atlantic Ocean (38º 43.76’ N, 075º 03.42’ W) to eliminate discharges and associated water quality problems in the Inland Bays. Members of the Delaware Chapter of Surfrider Foundation have opposed this plan, concerned that the ocean water quality would suffer. Instead, the chapter supports land application of the treated wastewater and increased use of reclaimed water for irrigation as a way of lessening the sewer discharge to the ocean and also to conserve fresh water supplies during times of drought. You can read comments from Surfrider's Delaware chapter here. There is a substantial amount of technical information on this issue (reports, cost estimates, presentations) on the City of Rehoboth Beach Website. More info. Here's a July 2014 article from delawareonline that discusses this issue and raises another treatment alternative - constructed wetlands.
UPDATE: In January 2015 Rehoboth Beach Mayor Sam Cooper announced that the city's controversial ocean outfall project had been approved. A completion date of June 1, 2018, has been set. Cooper said a long-delayed approval of the city's environmental impact statement, sitting for about two years on the desk of the secretary of the Department of Natural Resources and Environmental Control, has now been approved. Surfrider Foundation's Delaware Chapter is appealing this decision.

In nearby Maryland, Ocean City's wastewater treatment plant also uses an ocean outfall. The Ocean City outfall system includes an outfall pumping station located at the Wastewater Treatment Plant, approximately 700 feet of ductile iron pipe from the Wastewater Treatment Plant to the beach area, an air release valve vault just short of the beach and 4,600 feet of pre-stressed concrete cylinder pipe discharging to a diffuser section which is in water approximately 30 feet deep. The 1,000 foot long diffuser section has 50 4-inch risers which extend approximately 7 feet above the center line of the pipe, ending in 4 inch by 4 inch tees that are intended to discharge effluent parallel to the beach. The effluent is diluted to 1 part effluent to 200 parts water.

Information on the location or number of storm drains in Delaware was not found. However, DNREC staff reports that storm drains are mapped, and this inventory is updated regularly. The data are kept by the DNREC Division of Water Resources and are available online and in published form.

Stormwater Ocean Outfalls in Rehoboth Beach. Source:GHD

In Rehoboth Beach, storm drain outfalls are located at Grenoble Place, Maryland Avenue, Rehoboth Avenue, Laurel Street and Delaware Avenue. As part of Secretary David Small's record of decision greenlighting the ocean outfall for the Rehoboth sewer system (see above), Delaware Department of Natural Resources and Environmental Control mandated the city submit a report on the water quality in five stormwater outfalls that empty into the ocean. More on this.

Storm drains are permanently posted if they are part of a Combined Sewer Overflow (CSO) system. This only occurs at two locations — Wilmington (80 miles from the beach) and Seaford/Blades (30 miles from the beach in the Chesapeake watershed).

According to NRDC's 2004 Testing the Waters report and subsequent reports, Rehoboth Beach is affected by rainfall due to the presence of stormwater outfall pipes on the beach.

An article in the Delaware News Journal by Jeff Montgomery and Molly Murray on November 7, 2004 noted the following:

About 80,000 cesspools, seepage pits and septic systems operate near homes and businesses around the state. In towns such as Harrington, Milton, Bridgeville, Seaford, Mills borough and Rehoboth Beach, treated sewage continues to flow into the rivers and canals despite federal mandates that the practice eventually be stopped. In Wilmington, sewage and runoff during rainstorms combine to overload the state's largest treatment plant, which relies on an antiquated system that collects both sewage and stormwater. Even after light rains, the surge overwhelms the pipes, some of which are wooden, and unreated waste goes directly into the Christina River and the Brandywine.

The Wastewater Facilities Advisory Council - 2008 - Long-Term Wastewater Facilities Funding Plan FY 2009 - FY 2014 identifies funding needs for wastewater system improvements and expansions. The conclusions of the report are:

  • There are $293.8 million in Statewide wastewater facility funding needs for future projects through 2014
  • Available sources of grant funds are insufficient to offset the high costs of new sewer projects or to enhance existing wastewater treatment facilities to meet new water quality standards
  • $60 million is needed for additional loans and grants to make the projects affordable to moderate and low income users over the next six years

The Coastal Nonpoint Program was developed in accordance with Section 6217 of the Coastal Zone Act Reauthorization Amendments of 1990. Here is a link to the 2007 Annual Report.

The coastal resources of Delaware are of significant value. Nonpoint sources (NPS) have been identified as significant contributors to water quality pollution. The Delaware Coastal Programs (DCP), in cooperation with the Delaware Nonpoint Source Program and other programs within the Department of Natural Resources and Environmental Control (DNREC) are committed to controlling NPS pollution in Delaware's waters.

Water Quality Contact (Runoff and Outfalls)

Kathy Bunting-Howarth, Director of Water Resources
Department of Natural Resources and Environmental Control

Debbie Rouse
Environmental Scientist
Recreational Water Program
Delaware Department of Natural Resources and Environmental Control
820 Silver Lake Plaza – Suite 220
Dover, DE 19904
Phone: 302-739-9939
Beach Hotline: 1-800-922-WAVE

Michael Bott
Environmental Scientist
Recreational Water Program
Delaware Department of Natural Resources and Environmental Control
820 Silver Lake Plaza – Suite 220
Dover, DE 19904

Bonnie Willis
Delaware Coastal Programs
89 Kings Highway
Dover, DE 19901
Phone: (302) 739-9283

Delaware NPS Program Staff

Program Manager - Robert Palmer

Environmental Scientist - Sharon Webb

Environmental Scientist - Lara Allison

Planner - Mark Hogan

Perception of Causes

The DNREC suspects that contamination at inland bays is likely a combination of poor tidal exchange, natural sources of bacteria, and runoff from a watershed with a surface area 10 times greater than the inland bays; the agency is starting DNA work to document bacterial sources.

DNREC indicates the main causes of ocean water quality problems in Delaware are rainfall/runoff and "ubiquitous bacteria/re-suspension of substrate. Primarily wind driven." The greatest regional threats to ocean water quality are considered by DNREC staff to be outdated or undersized treatment facilities, excess nutrients, point source pollution (Inland/Coastal Bays), Non-point source pollution and exponential population growth.

The state’s monitoring data is used to determine which watersheds should be assessed for placement of nutrient/bacteria buffers that reduce the introduction of pollutants. These buffers consist of setbacks or vegetation that reduce the amount of nutrients and bacteria that get carried to surface waters in runoff.

According to Delaware’s 2004 combined 305(b) and 303(d) report, 94 percent of assessed river miles and 68 percent of assessed lake acres do not meet criteria for primary contact recreation, such as swimming, bathing, or water skiing. Forty-one percent (12 square miles) of assessed estuaries fully support primary-contact recreation, 44 percent (13) partially support, and 15 percent (4.5) do not support primary-contact recreation. Of the 25 miles of coastal waters assessed, 100 percent fully support primary-contact recreation. Of the 2,509 river miles assessed, 94 percent (approximately 2,360 miles) do not meet criteria for primary contact recreation. The report, however, also states that 99 percent of the assessed river miles contain indicator bacteria—enterococcus and coliform—above levels considered to be acceptable for primary-contact recreation. The report does not explain the discrepancy between the two percentages. River contamination largely stems from unidentified diffuse, nonpoint source pollution. Delaware assessed 2,954 lake acres in 2004. Sixty-eight percent of lake acres do not meet criteria for primary-contact recreation. Similar to rivers and streams, a greater portion of lake acres (87 percent) contain indicator bacteria above levels considered acceptable for primary contact recreation. Some areas with high indicator bacteria may be monitored for other uses than just primary-contact recreation. Again, pathogenic indicators (bacteria), nutrients, and toxic chemicals are the leading causes of contamination. Agricultural runoff, unidentified nonpoint sources, urban runoff, and municipal and industrial point sources are the primary sources of nutrients and toxics. This website has additional reports for 2006 and 2008.

Public Education

According to DNREC, the state uses books, brochures, their website, signs, and maps to educate the public about water quality issues and water quality improvements.

Information on non-point source pollution and pollution prevention is available on DNREC's website:

Delaware has several programs that promote public participation in water quality improvements: Coast Day, Adopt-a-Beach, an annual coastal cleanup event, and Beach Grass Planting.

Clean Marinas

The Delaware Clean Marina Program, launched in June 2003, is a partnership between DNREC, the University of Delaware College of Marine Studies and the BoatU.S. Foundation. The program aims to reduce damage to the environment caused by marina and boating activity.

The Clean Marina Advisory Committee -- made up of members from DNREC, the U.S. Coast Guard Auxiliary, UD Sea Grant and the BoatU.S. Foundation -- offers technical assistance and referrals to help increase compliance and participation.

The U.S. Environmental Protection Agency and the National Oceanographic and Atmospheric Administration have provided technical assistance. The Center for the Inland Bays has provided grant funding for the program.

Participating marinas that want to ensure they are ecologically responsible can sign a pledge to follow existing laws and institute recommended practices. After a compliance and upgrade period, marinas can seek certification, which allows the marinas to fly the Clean Marina flag and use the logo on all promotional material. It also entitles them to be included in promotional and outreach efforts by DNREC.

Educating marina users and members is the responsibility of the marina operators. Easy-to-read signs and informative displays do part of the work. In addition, operators can write certain requirements into slip lease agreements that hold boaters to Clean Marina standards.

General Reference Documents

EPA has compiled several NPS (Nonpoint Source) Outreach Products that are a selection of television, radio, and print products on nonpoint source pollution that have been developed by various agencies and organizations around the country. They are good examples of outreach in the mass media. Also see What You Can Do.

NOAA, in partnership with the U.S. Environmental Protection Agency, International City/County Management Association and Rhode Island Sea Grant, has released an interagency guide that adapts smart growth principles to the unique needs of coastal and waterfront communities. Smart Growth for Coastal and Waterfront Communities builds on existing smart growth principles to offer 10 coastal and waterfront-specific guidelines that help manage development while balancing environmental, economic, and quality of life issues.


  1. Susan Love, Resource Planner, Delaware Coastal Management Program, written communication. February 14, 2001.

State of the Beach Report: Delaware
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