Order effective July 18. Harvest will reopen Aug.14
UPDATE: In a press release dated July 25, DNREC officials said "The 21-day closure in effect for potential public health risks extends from July 24 to Aug. 14."
It will be at least three weeks -- and perhaps longer -- until it is safe to harvest shellfish or go swimming along the bayside.
A partial shutdown at the county wastewater treatment plant caused DNREC Secretary Shane M. Garvin to issue a July 18 emergency order to close recreational and commercial shellfishing in part of the Delaware Bay. The order affects harvesting of clams, mussels, and oysters in Delaware’s part of the bay north of the Mispillion River, near Milford.
The order will be lifted 21 days after repairs at the plant are complete, and tests confirm bacteria levels in the water have returned to safe levels.
It does not apply to crabs and conches.
The order was prompted by a failure at the Kent County Regional Resource Recovery Facility on Milford Neck Road, between Frederica and Milford. It treats sewage and wastewater from all over Kent County; once processing is complete, the water is discharged into The Gut, a tributary of the Murderkill River.
It flows to the Delaware Bay at the town of Bowers. Wave action disperses the effluent along the Kent and Sussex coastlines.
DNREC has reported the amount of undertreated wastewater that went into the river is not known, although the plant can process up to 10 million gallons of treated wastewater per day.
In November the plant completed a multi-million dollar upgrade allowing it to process an average of 12.5 million gallons a day.
Kent County Public Works Director Andrew Jakubowitch said the problem was traced to one of two 20-million-gallon aeration basins.
Wastewater coming into the plant is run through a series of screens before flowing into the basins, which are about 16 feet deep. Oxygen is introduced into the mixture, stimulating trillions of microorganisms that feed on and break down solids in the water. The wastewater then goes through additional processes to remove the solids and purify the water before it is discharged into the river.
At the moment, however, that’s not entirely the case, Jakubowitch said.
“We are discharging water that’s not completely treated to the level we’re required to treat it to,” he said. “That means there is a potential for health issues.”
While the sides of each basin are concrete, the bottoms are clay and rock, covered by a thick layer of geotextile fabric, Jakubowitch said. Around the end of June, the liner in one of the pits developed a hole, allowing the water to seep underneath. Accumulating gases created a large bubble, nicknamed a “whale,” that lifted the plastic off the bottom, stopping the oxygenation process.
The other basin, undergoing maintenance, was dry, he said. Workers are hurrying to finish repairs, and the first basin will be drained and the liner replaced.
Without aeration, discharge into the river contains more solid particles and nutrients than allowed and increases the probability of higher levels of phosphorus and nitrogen flowing into the Delaware Bay.
This incompletely treated water has the potential to introduce greater levels of bacteria into the water which affects marine life, said Chris Bason, executive director of the Delaware Center for the Inland Bays.
“Shellfish, primarily oysters, get their food by filtering small particulates out of the water with their gills,” Bason said. “This bacteria can accumulate in their tissues and if harvested and eaten, can make a human sick.”
Some of this bacteria can include Enterococcus, a cause of urinary tract infections; some strains are known to be resistant to antibiotics. While there is no commercial oyster harvesting ongoing in the bay now, recreational hard clams are being gathered.
However, Bason thinks the probability of contaminated shellfish is relatively low. But higher than usual amounts of phosphorus and nitrogen in the water can stimulate the growth of algae blooms and decrease oxygen levels. This can be critical when it comes to future finned fish catches, he said.
“This is a hot time for young fish,” Bason said. “They’re feeding and working to grow into larger fish. It’s a time of intense growth.” A significantly reduced oxygen level could conceivably slow down that growth or drive young fish into other waters.
The undertreated water can cause other problems. In his emergency order, Garvin advised people not swim near the Mispillion and avoid contact with the bay water. Jakubowitch said people with weak immune systems also could have problems with water.
That warning caused some worry in Bowers, a small beach community on Delaware Bay at the mouth of the Murderkill River, north of the Mispillion.
Town Councilman Bob McDevitt, who handles Bowers’ zoning, said he was advised about the problem after returning from a trip.
“I was unloading the car and the neighbors told me about what’s going on,” he said. “I checked online and saw DNREC’s shellfish advisory. But I noticed the last line that talked about not coming in contact with the water.
“That’s when I went out and started putting up ‘no swimming’ signs, because of the bacteria in the water,” he said.
This was not the first time the wastewater plant has had problems with basin liners: something similar took place in 2012 and 2007. The basins themselves date to the 1970s when the plant was built.
DNREC also suspended shellfish harvesting in February when repairs in Magnolia caused an overflow at a Dover pump station. The failure discharged hundreds of thousands of gallons of untreated sewage into the St. Jones River.