Published: June 13, 2009 10:29 pm      

Algae blamed for Shawnee’s woes

It has taken years of sampling and study, but the state Department of Conservation and Natural Resources feels it finally has a handle on what’s ailing the water at Shawnee State Park.

“The problem is just plain blue-green algae,” said Andy St. John of DCNR. “The numbers are roughly at least three times what they were in 2000. All of the numbers are much higher than what they were.”

The over-abundant algae clouds the water, and the resulting turbidity blocks sunlight from reaching aquatic vegetation. That caused the lake’s once-abundant weed beds to die off, depriving big fish of feeding areas and small fish of sanctuaries from predators. And although the devastated fishery is the subject of most complaints, the loss of Shawnee’s weeds also spelled doom for less-noticed animals such as frogs, turtles and aquatic insects, and prompted once-abundant flocks of birds such as ducks and cormorants to go elsewhere for food and nesting habitat.

Many of the park’s former human users have moved to more pleasant surroundings as well.

Even recreational boaters are scarce at Shawnee these days, presumably because its murky waters hold little appeal.

“Even if there wasn’t a fishery concern, there’s an aesthetic problem,” St. John conceded.

“Nobody wants to recreate in that lake.”

After years of trying to determine what was causing the problem and come up with a remedy, DCNR finally decided to bring in outside help. In February, it contracted to Princeton Hydro LLC of New Jersey to review the available data and provide recommendations.

“The scientific explanation is that Shawnee ‘has entered an alternative stable state,’ ” St. John said.

“In plain words, it ain’t what it used to be, and it seems to be staying that way. Once, that lake was dominated by submerged vegetation. Now, it’s dominated by algae.”

That’s something St. John had previously suspected, but was not entirely sure about. In fact, he had scheduled a treatment with algae-killing copper sulfate two years ago, but backed off when water samples showed more suspended solids than algae.

“It turns out the suspended solids number was a spike and didn’t really mean anything,” St. John said. “But, I really wanted a consultant to put their recommendations in there and make sure we weren’t missing something. We’re not.”

But, although the culprit for the lake’s problem has been found, the mystery of the underlying cause remains. Survey results show that the lake contains high levels of phosphorous, which is the fertilizer fueling the algae bloom. The source of that phosphorous is unknown at this point.

“I think we all know there’s a fair amount of agriculture area up there,” St. John said of the watershed drained by Kegg Run and Shawnee Creek, the lakes’ main tributaries. “But, I don’t want to imply that the upstream landowners are doing us wrong. I don’t think it’s necessarily bad agriculture practices.”

So, DCNR’s consultant has recommended another year of sampling and surveys, this time concentrated on what is in the tributaries and how it affects the lake.

“We’ve already started,” St. John said. “DEP has kicked in funds and staff. So has the Bedford County Conservation District.

“I know this is frustrating for the bait shop owners and the lake users,” St. John said. “It’s frustrating to me as well. But by Nov. 1, we should have all the data we need. There is no use in trying to fix the lake until we know how much phosphorus is coming into it.”

Meanwhile, though, DCNR is gearing up for action as soon as the final figures are in. Help has been sought from the state Department of Environmental Protection, which has jurisdiction for the tributaries beyond park boundaries, and the county conservation district has an effort under way to set up an organization of volunteers to help take water samples and to implement some remedies such as planting streamside and aquatic vegetation.

“We need help,” St. John said. “We don’t have the manpower to go after it. And, finding the money for this is going to be pretty tough. But, we’ve begun collecting names. Once we get a group in place, we have a way to find money.”

St. John is considering revisiting his plan for an algae-killing copper sulfate treatment early next spring, allowing life-giving sunlight to reach the lake bed, if only temporarily. There are also discussions about treating the lake with aluminum sulfate, which bonds to the phosphorous and sinks it to the lake bed.

If new weeds can be planted, clearing the water may allow them to survive long enough to contribute to the effort.

“Weeds use phosphorous,” St. John explained.

“Any phosphorous they use will not be available for the algae.”

The Pennsylvania Fish and Boat Commission is also thinking about stocking muskellunge fingerlings in the lake next year in the hopes they will trim a burgeoning population of gizzard shad.

Gizzard shad, St. John said, feed on phytoplankton which, in turn, feed on blue-green algae.

Fewer shad could mean more phytoplankton, he said, which will, in turn, help the problem by eating algae.

Eventually, St. John said, Shawnee will again be a popular place to fish and boat, although he warned it will never be the same.

“Even man-made lakes age, and we don’t want people to believe that this lake should return to where it was 10 years ago,” St. John said. “But, I’d like to get that fishery back.”

Princeton Hydro’s report is in draft form.

When it is finalized, St. John said, it will be posted on Shawnee’s Web site (www.dcnr.state.

pa.us/stateparks/parks/shawnee.aspx) so the public has access to it.