Rehoboth Bay creeks ‘highly impaired’ by nitrogen, development to blame: Report

By Julia Rentsch, Salisbury Daily Times

Delaware’s inland bays were healthy half a century ago, but today face many challenges.

Pollution present in creeks that feed fresh water into the bays is a major reason why. Not only does the pollution eventually make its way into the bays, it makes the creeks themselves poor places to recreate, fish or swim.

A new report explains just how bad pollution has gotten in Herring and Guinea creeks, which flow through suburban and rural areas south of Lewes to feed Rehoboth Bay.

Swimmers, boaters and anglers in the bays once enjoyed clear waters, meadows of sea grass, healthy oyster reefs and diverse and plentiful fish populations.

But today’s bays are “tarnished treasures” that tell a different story, said Chris Bason, executive director of the Delaware Center for the Inland Bays.

While still picturesque, the bays lack their sea grass beds and the oyster reefs have largely disappeared. Algal blooms are frequent in the more stagnant areas of the bay, which block underwater plants and animals from the sunlight they need to flourish.

“It will require around $100 million to return Delaware’s bays and tributaries to state and federal standards,” said Laura Miller of the Delaware Nature Society, a nonprofit environmental education and advocacy group.

The new Delaware Center for the Inland Bays report, released Monday, Sept. 16, found extraordinarily high nitrogen levels in the creeks, with nitrogen levels in both creeks on average registering 10-12 times higher than the limit considered ecologically healthy.

The report was developed in conjunction with members of the University of Delaware’s Water Resources Agency. The study analyzed eight environmental indicators to learn about changes occurring in the creeks.

“High levels of nutrients may sound like a good thing, but is actually very bad for waterways,” said Marianne Walch, science coordinator for the Center for the Inland Bays and lead author of the report. “It puts them at risk for a number of problems, including overgrowth of algae, poor water clarity and unhealthy conditions for fish and people.”

Though the Herring and Guinea creeks’ 34-square-mile watershed does not include any major towns, rapid development and the installation of numerous septic systems are key causes of the pollution, the report says.

Development in the creeks’ watershed areas increased by 68% between 1992 and 2012, with most development occurring nearest the bay, and the watershed now has one of the highest densities of active septic systems anywhere around the Inland Bays, it reports.

As the Guinea and Herring creeks’ watershed developed, it lost significant amounts of its forests and wetlands that helped absorb pollution from nearby urban and agricultural areas before it made its way into the river, the report says.

Despite years of work to try to reduce nutrient pollution in both creeks, pollution levels remain high and in some contexts is even worsening — phosphorous levels in Herring Creek have been trending upward since 2007, for reasons unknown, the reports states.

“A full 90% of Delaware’s waterways are considered polluted by excess nutrients and other toxic substances,” Miller said.

“But I do have some good news for you: we know how to fix these problems, which are not unknown to us and they not new to us,” Miller said.

The Clean Water for Delaware Act, which would provide $25 million per year in dedicated funding for water quality improvement and flood reduction projects around the state, has been referred to the House Appropriations Committee and will be reviewed during the 2020 session.

Should the funding be allocated, it will be used to assist in the cleanup of such polluted waterways as the Herring and Guinea creeks.

But the picture isn’t all gloomy for the important creeks, as there are ways to help reverse the negative trend.

Protecting forest buffers along shorelines can help mitigate impacts from development by filtering runoff and taking up excess nutrients while also benefiting native wildlife. Developers and communities can also adopt green infrastructure practices to limit runoff in developed areas.

And, while the number of septic systems in the watershed is concerning scientists, work is being done to convert the septics into less-polluting sewer districts. Sussex County and private wastewater utilities are working to expand sewer services to more communities in the Herring and Guinea creeks’ watershed.

Converting from septic to sewer can cost homeowners thousands of dollars. To help with costs, Sussex County has for the past few years offered financial assistance to low-income residents through grants or loans.

Today, nearly every property along the two creeks and other waterways east of Route 24 either have converted to central sewer service or have plans to convert, the report says. Over time, this conversion should result in cleaner water.

“That means a lot of nitrogen that won’t be going into our creeks and bays,” Walch said. “So, kudos to Sussex County for this.”


This article originally appeared in Delmarva Now on September 18, 2019. View the article.