Lewes BPW offsets effluent nutrients

The Lewes Board of Public Works is removing chicken manure from farms to offset the nutrients it adds to the Inland Bays watershed when it dumps treated effluent into the Lewes-Rehoboth Canal.

General Manager Darrin Gordon said the state requires the BPW to remove an equal amount of nitrogen and phosphorous as it may add into the Inland Bays. He said only 2.5 percent of the BPW’s treated effluent reaches the Inland Bays. 

In 2009, the BPW removed 358 tons of manure from a local farm, which, at the time, gave the BPW credit for about 80 years worth of added nutrients. The manure can be taken anywhere outside the watershed; the BPW’s is taken to Pennsylvania. 

Recently, Gordon said he received a phone call from a DNREC official saying the numbers calculated in 2009 were incorrect. It turns out the BPW will receive credit for one-tenth of the original amount. 

“We’re still good for another year or so,” he said. “But we’re going to have to move more.” 

Based on DNREC calculations, the BPW has a credit of about 100 tons of manure remaining. At an average rate of 2.84 tons used per month, the BPW has enough in the bank to last 33 months. 

Gordon said he isn’t going to wait that long.

“I’m going out and finding more chicken manure in the Inland Bays watershed,” he told BPW directors at their March meeting. “We’re going to be paying for it, so I just wanted to let you, the board, know.”

So, why were the numbers so far off? Gordon said DNREC officials reexamined the calculations and determined them to be inaccurate because only a portion of the nutrients in chicken manure, if applied on a farm field, would make it into the Inland Bays watershed. The BPW had previously been taking credit for all the nutrients in the manure. 

“So instead of 100 percent credit for manure removal, I’m getting about a tenth of it,” he said. 

The cost to remove an amount equivalent to the 2009 project is $3,500 to $4,000, he said. 

“Is it worth us going to a scientist and engineers and then fighting the state?” Gordon asked. “It is my opinion that it’s not worth the fight. I’ll just find some more manure and get it moved.”

Gordon said all point-source polluters are required to offset nutrients added to the waters.

Removing chicken manure is just one way to remove nutrients from the watershed. Just a few years ago, the BPW considered harvesting oysters as a means to bump their numbers with the state. However, the plan was abandoned when BPW officials were informed they had already banked more than enough through the manure removal project. 

According to the U.S. Geological Survey, nitrogen and phosphorous are nutrients essential for plant and animal growth, but too much in waterways can cause adverse health and ecological effects – including fish kills. 

Gordon said the BPW’s water is cleaner than most. 

“Our effluent is some of the cleanest around,” he said. “It’s times cleaner than the canal we’re putting it into.”