When lake suffers, we all do

A blanket of algae on Bystre Lake hurts wildlife and raises the risk of flooding in nearby neighborhoods.

By DAN DeWITT, Times Staff Writer
Published December 23, 2007

Sue Bathauer, left, and Vera Huckaby watch Bystre Lake during the Audubon Society's Christmas Bird Count on Dec. 15.
	[Keri Wiginton | Times]

BROOKSVILLE - If the sight of hundreds of vultures roosting in dead trees around Bystre Lake wasn't grim enough, Bernie Bathauer offered this dispiriting news:

Recent tests by Florida Lakewatch revealed that Bystre, one of the largest lakes in Hernando County, is loaded with contaminants.

"It's very bad ... and the public doesn't seem to care," Bathauer, a Lakewatch volunteer, said during the Hernando Audubon Society's Christmas Bird Count on Dec. 15.

Choked with nutrients is a more accurate description, said Eric Schulz, Lakewatch's regional coordinator. The levels of nitrogen and phosphorus are extraordinarily high, according to Schulz and Catherine Wolden, an environmental scientist at the Southwest Florida Water Management District.

Those nutrients have promoted the growth of green algae so thick that kayak paddles vanish in the murk. The wading birds and ducks that once flocked to the lake have disappeared, as have the anglers that formerly made Bystre a popular fishing spot.

In the coming years, "you're going to have encroachment of vegetation until it kind of takes over," Wolden said. "It's not very conducive to it being a lake anymore."

The accumulation of decaying plants may also pose a threat to houses in Bystre's 24-square-mile drainage basin, already one of the most flood-prone in the county.

Stormwater in that area, which includes eastern Brooksville, collects in Bystre, said John Burnett, the county's water resources specialist.

"When the lake fills up with vegetable matter," Burnett said, "it displaces the area we depend on for water storage."

Far too fertile

Moderate amounts of nitrogen and phosphorus feed aquatic vegetation, which supports amphibians and small fish, and, in turn, a healthy population of large, predatory fish and birds.

But at higher levels, the lake becomes "hypereutrophic," which means, Schulz said, "way more nutrients than you need. ... It's almost like the lake is too productive for its own good."

In scientific terms, hypereutrophic is defined as lakewater with more than 1.5 parts per million of nitrogen, 0.1 part per million of phosphorus and visibility of less than 3 feet.

In August, Swiftmud measured 10 parts per million of nitrogen and 1.2 parts per million of phosphorus. In April, Bathauer and another volunteer with Lakewatch, which is affiliated with the University of Florida, lowered a white disk into the water to test its clarity.

"At 3 inches, it was totally gone," Bathauer said.

Wolden cautioned that the Swiftmud measurements had not been verified by other scientists, as district policy requires. She also said the jump in the concentration of nutrients over the past two years might be mostly because of the drought, which has greatly reduced the volume of water in Bystre. The center of the lake, about 9 feet deep in 2004, was less than a foot deep in August.

That is so low, Schulz said, that nutrients from the lake bed probably skewed the measurements.

"Basically, what we're talking about at this point is a mud puddle," he said. "You're definitely getting sediment coming up into the sample."

But before the nitrogen and phosphorus levels spiked, they had been climbing steadily from 1993 to 2004, when the lake was high and nitrogen was measured at more than twice hypereutrophic levels and phosphorus at nearly four times the standard.

That corresponds with the impression of residents who know the lake: that its long, slow decline has accelerated alarmingly in the past two years.

The lake, which lies north of State Road 50 and south of Mondon Hill Road, has long been one of the county's best places to see wading birds and waterfowl, said Mike Liberton, who led the Audubon group that counted birds at Bystre.

"I know we're not seeing the ducks we used to," Liberton said. "This year, we did not see one pied-billed grebe, and I can't ever remember that happening."

"The number of birds was just insignificant compared to what we usually have," Bathauer said. "It just declined and declined, but the last year has really been terrible."

Jim Adkins, the former Brooksville fire chief whose family owns a 226-acre cattle ranch on the northern edge of the lake, said fishing boats were once a common sight on Bystre. Not anymore.

"The lake is sad right now," he said.

Troubles date to 1926

Adkins' cattle may be part of the problem, as are droppings from the birds, Wolden said, but the fertilizer he uses is not.

The nitrogen is nearly all from natural sources, Wolden said, although the lake's unnatural history has contributed to its premature aging, according to an 18-year-old study on flooding in the Bystre basin commissioned by the county.

Between 1926 and 1967, the former McDonald Mine, north of Bystre, dumped up to 5,500 gallons per minute of silt-laden water into the lake. These tailings, as miners call them, filled the basin and created a shallower, larger lake, which spilled over its historic banks, killing the oaks on the southern shore.

More importantly, the silt created an impervious bed, trapping nutrients that might otherwise have seeped underground, the 1989 study by the Dames and Moore engineering firm said. Because most soil in Central Florida is rich in phosphorus, the tailings may have also started loading the lake with nutrients, Schulz said.

Phosphorus does not dissipate naturally, he said, "so that is in the loop for the future. Even if no more phosphorus ever came into the lake, that would be enough to make it a productive lake for many years."

A downward trend

Swiftmud is concerned enough about Bystre that in 2005 it began monitoring water quality during the winter and summer every year rather than every three years, Wolden said. The state Department of Environmental Protection does not have results of those tests, but such readings may eventually lead it to place Bystre on the list of impaired lakes.

That would allow the state to take action such as creating holding ponds for runoff or even dredging the lake to reduce nutrients, said Jan Mandrup-Poulsen, an environmental administrator with the DEP.

But Hernando residents may have to get used to the idea of degraded lakes if the county continues to develop as it has, Burnett said.

Rainfall has generally declined over the past 40 years, he said, while pumping for houses and golf courses has increased.

"We have less supply and more demand, and we have lakes that don't have water in them," he said. "Water temperature goes up, dissolved oxygen goes down, fish die and we get algae growing on all these nutrients. The lake changes into a different kind of lake, and that's what I think we're seeing."

Dan DeWitt can be reached at dewitt@sptimes.com or 352 754-6116.

[Last modified December 22, 2007, 20:40:59]