Dirickson Creek found polluted with nutrients, bacteria

The first time Barbara Shamp visited Swan Keys on Little Assawoman Bay, she knew it was the perfect place to retire with her husband.

They purchased a corner lot across the water from Mulberry Landing in Assawoman Wildlife Refuge over a decade ago, after spending an evening admiring a winter sunset reflecting off the surface of the calm bay waters.

“We spent 20 years looking for waterfront property from Canada to Florida, but the Mid-Atlantic really spoke to us,” Barbara said.

But they were quite alarmed the first time they jumped in the water of Dirickson Creek, a tributary of the bay that flows parallel to Route 54 between Fenwick Island and Selbyville.

“You sink in mud up to your knees, and that's an experience,” she said. “You come up and you have black, slimey, oily mud all over the legs.”

When Barbara fell off their boat near the dock and scratched the front shin of her leg, she quickly learned mud isn't the only problem. It took at least three months for the wound to heal, she said, raising her awareness about the health of the nearby waterway.

She learned from her neighbors that the creek struggles with environmental problems, including high concentrations of nutrients and bacteria.

“We were just becoming aware that pollution on the waterways of the state was a major issue,” Barbara said. “We couldn't believe the difference between here and the Chesapeake Bay.”

In 2015 the Shamps joined a team of citizen scientists, guided by experts at Delaware Center for the Inland Bays, to fully assess the health of the creek. This is the second Your Creek Initiative project the center has spearheaded in an effort to get detailed snapshots of the environmental challenges in Inland Bays tributaries.

The resulting report on Dirickson Creek, released in late June, found the waterway suffers from high levels of nitrogen and phosphorus, excessive bacteria and low dissolved oxygen, which worsens upstream, said Andrew McGowan, an environment scientist at the center.

“The creek is different depending on where you're standing,” he said, pointing to clearer open waters where the bay and the creek meet along the shores of the Assawoman Wildlife Refuge. Dilution and tidal flushing at the mouth of the bay help keep levels down, but there is little flushing in the upper reaches of tributaries and canals, leading to higher nutrient and bacteria concentrations.

Excess nutrients are the creek's No. 1 problem, mainly in the upper reaches of the creek and in residential canals, he said. Nutrients, in moderation, fuel healthy marine ecosystems by fueling the growth of grasses and algae. Too much nitrogen and phosphorus in a waterway can harbor algal blooms, which can consume dissolved oxygen in the water, often resulting in the deaths of marine animals and bay grasses.

“The creek is getting too much of a good thing,” said Anna vonLindenberg, the Dirickson Creek team leader.

Dirickson Creek is considered an impaired body of water under the federal Clean Water Act because of excessive nutrient and bacteria levels. The Environmental Protection Agency has established pollutant caps known as a total maximum daily load, or TMDL, designation for the Little Assawoman Bay with the goal of reducing nitrogen, phosphorus and bacteria levels by 40 percent.

Bacteria levels in most areas of the creek are high enough to warrant swimming advisories from state officials because ingestion of the bacteria found in the water can potentially cause gastrointestinal problems or other diseases.

The report found bacteria levels near Old Mill Bridge over the creek exceed safe swimming standards for more than three-quarters of the summer season. Levels at Mulberry Landing downstream were found to be much lower, generally safe for swimming.

The report found most nutrients come from indirect sources, such as runoff from farmland or residential development. The loss of forests and marshes and increase in impervious surfaces – such as roads, roofs and parking lots – also allow more pollutants to reach the creek.

“Our cleansing woods are disappearing,” vonLindenberg said.

More than 42 percent of the 20-square-mile watershed surrounding the creek is dedicated to agriculture, but about 1.5 square miles of farmland has been developed in recent years, the report found.

If residents and elected officials ignore the problems of Dirickson Creek – overdevelopment, failing septic systems, loss of marshes – there could be negative impacts on the recreational and tourism-driven industries that support the area, vonLindenberg said.

“Land use in the watershed is of paramount concern to the health of our creek,” she said. “We should protect our creek not just because it's the right thing for our health and for the creek's health, but because it's the fiscally right and responsible thing to do.”

To read the full report, go to www.inlandbays.org/dirickson-report.