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Dover Post
  • City monitors algae bloom at depleted, green tinted Silver Lake

  • City and state officials are monitoring the algae bloom that has brought a green hue to the depleted waters of Silver Lake and worries of another fish kill in Dover.


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  • City and state officials are monitoring the algae bloom that has brought a green hue to the depleted waters of Silver Lake and worries of another fish kill in Dover.
    The green tint pervaded the entire lake Wednesday afternoon as well as the St. Jones River connected to the lake via a concrete spillway, the artificial channel used for overflow of Silver Lake.
    Silver Lake was depleted as the city tried to remedy a fish kill that occurred between late July 17 and early July 18, City Manger Scott Koenig told the Dover Post Wednesday.
    The city wanted to provide more oxygen to the fish below the spillway by opening the valve to allow aerated water from Silver Lake to spill into the St. Jones River, Koenig said.
    “So, by trying to solve one problem we may have inadvertently caused another,” he said. “There is concern we could have a fish kill in the lake. We’ve got several more weeks of summer before we get into cooler water. The storms last week seemed to have raised the level some, but it’s not back at the normal level.”
    As a result, the Dover Department of Public Works was working with the Delaware Department of Natural Resources & Environmental Control to monitor Silver Lake in anticipation of another, possible fish kill in the St. Jones Watershed, Koenig said.
    DNREC Division of Fish & Wildlife biologists and environmental scientists investigating the earlier fish kill found that high temperatures, low water levels, little rainfall and an algae bloom led to lethally low dissolved oxygen levels in the St. Jones River. They estimated the kill entailed 3,150 gizzard shad juveniles and adults, along with 888 bluegills, 180 white perch and 110 catfish, plus a few black crappie, American eels, hog chokers and largemouth bass.
    Dover resident Sherman Townsend, whose home abuts Silver Lake, expressed disappointment to Dover City Council Monday night that the valve to Silver Lake had been opened to allow that much water to escape in the middle of summer. He said that usually only happens in the fall.
    As a result, Townsend said Silver Lake’s lower water levels would cause a rise in water temperature and, therefore, cause the algae bloom. As Townsend left city council’s meeting he expressed his belief that Koenig and his staff would remedy the situation.
    Page 2 of 2 - Indeed, Koenig said a staff member opened the spillway valve to let some water flow into area below the damn.
    “The problem was that the valve was open for too long and two wide in trying to save the fish below the spillway,” he said. “Under normal circumstances, you wouldn’t have opened that valve to let that much water be released.”
    Koenig said internal city policy would be revised so that this sort of thing does not happen again in the future.
    As for finding a remedy now, city officials had discussed the idea of pumping water into Silver Lake, Koenig said. But that idea was put to rest because city water was chlorinated and could alter the lake’s ecosystem. And it was not feasible to pump that much water in the middle of the summer, traditionally a time of drought, he said.
    “It could create more problems than it solves,” he said. “The only way the lake will return to its normal water level is by rain. There’s just no way for us to fill up the lake ourselves.”
    Among the visitors to Silver Lake on a pleasant, sunny Wednesday afternoon were Clarissa McMillan and Brandon Patterson, of Dover. They immediately noticed the green hue of the waters.
    “When the wind is still and you’re in the shade, the water is greener than the grass,” Patterson said.
    “I’ve lived in Dover my whole life and [Silver Lake] used to be a lot cleaner,” McMillan said, as her son Mason and his friend, Xabian, played in the playground. “This is starting to smell bad. And even if it were to rain more, so what? Then, we would have more dirty water.”
    McMillan hoped Dover would not just address the immediate problem presented by lower water levels. She wished the city would improve Silver Lake once and for all.
    “You go [to waterways] anywhere else in Delaware – Felton, Glasgow, New Castle and Wilmington – they look better than this,” she said. “This is the state capital.”
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