Exotic plant is growing in reservoir

Hydrilla poses possible problem for water supply

Piney Run Lake

Non-native species clogs intake pipes, can't be eradicated

January 20, 2002|By Mary Gail Hare | Mary Gail Hare,SUN STAFF

Water quality at Piney Run Lake is rated good to fair, but Carroll County water specialists have detected the presence of an exotic aquatic plant - commonly called hydrilla - that could cause problems if its growth is not controlled and the lake becomes a water source for South Carroll.

Recent monitoring showed that hydrilla verticillata, a non-native, fast-growing aquatic plant, has grown as tall as 3 feet and is visible on the surface along the shoreline.

"It is important to monitor this species' remarkable growth rate to determine its impact," a water assessment report from the county water resource planning division says. "It is unknown how hydrilla will affect the lake."

The agency's staff suggested annual aerial surveys during the plant's growing season, which could add to the $20,000 yearly cost of monitoring the lake.

Commissioner Julia Walsh Gouge discussed the contents of the report in a meeting last week with the Freedom Area Citizens Council, a South Carroll group that unofficially advises the county's three-member commission.

The Sun was allowed to review a copy of the report at the county planning office last week, but it is not yet available to the public.

The lake's water quality is important because the county plans to invest more than $15 million to construct a water treatment plant at the Sykesville-area lake in an effort to relieve chronic water shortages in South Carroll, the county's fastest-growing, most densely populated area.

Steven M. Nelson, county water resources specialist, called hydrilla a management issue. "We are just starting to scratch the surface, and we will have to monitor this plant continually," he said.

"Eradication is not possible. In excess, it is not a good thing for the water supply. We should be concerned from a water quality management standpoint."

"The assessment of water quality at Piney Run is good to fair, with good clarity," Gouge said.

"But an exotic plant is growing rapidly and eating the nutrients that keep the water clear," she said. "At this point, we have no way to eradicate it. It has to be harvested or it will reroot."

If hydrilla grows uncontrolled, pieces might break off and clog intake pipes of the treatment plant, the report said.

No one is sure how hydrilla got into Piney Run Lake. It could have been on the propellers of boats that had been in other bodies of water, or it may have been brought in by birds, Nelson said.

The commissioners ordered the report, "Assessment of Water Quality Conditions in Piney Run Reservoir," in preparation for the treatment plant.

The 18-page document is the result of months of studying the 2 billion-gallon lake, which was built 27 years ago for recreation, flood control and a future water supply. Surrounding Piney Run Park has become a favorite recreation spot drawing thousands of visitors annually.

A Web site of the University of Florida's Center for Aquatic and Invasive Plants says hydrilla is found in all types of bodies of water and has slender stems that produce tiny white flowers on stalks as long as 25 feet. It also produces potatolike tubers that attach to roots in mud, according the Web site.

It is in other bodies of water in Maryland, perhaps most notably the Potomac River, according to the Web site of the Western Aquatic Plant Management Society.

The discovery of hydrilla in the Potomac in the 1980s "has been viewed as mixed blessing," the Web site says. "Hydrilla does provide an important food source for waterfowl but has proved a detriment for navigation and recreational activities."

Gouge opposes construction of a Piney Run treatment plant, but Commissioners Donald I. Dell and Robin Bartlett Frazier have pushed ahead with the project, the cost of which is estimated at $15.2 million. The Maryland Department of the Environment has refused to issue a construction permit for the plant, which state officials say conflicts with the county's master plan for water.

The county report, which will be available to the public in a few weeks, describes water quality, addresses water supply issues, and provides data from several years of monitoring the lake and information vital to managing it as a fishery resource.

"Continued monitoring is essential to successfully managing the resource that is important both for a future water supply and for recreation," the report says.

Monitoring began in 1993 and has increased steadily. It is conducted at three stations on the 300-acre lake. The lake is sampled 18 times annually, twice monthly from April to October and once every month from November through March. Samples are taken from depths of 12, 30 and 50 feet.

"This is a way to evaluate our lake, compare it to other lakes and develop an index," Nelson said.

The report also details county efforts to safeguard the lake and the 500-acre park. The commissioners recently acquired 25 acres of land adjoining the park, much of it along streams that feed the lake.

"We now own the stream valleys all the way to the lake," Nelson said. "The more public ownership, the better the buffer from land use."

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