Wednesday, Feb. 13, 2008

Lake Needwood to be lowered

Dredging needed to make lake cleaner, more efficient for flood control

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County parks officials have begun to temporarily lower the level of water in Lake Needwood to prepare for a dredging project designed to make it cleaner and more efficient for flood control.

Project manager Andrew Frank of the county Department of Parks said the lake would be lowered about 2 and a half feet to allow survey work near Needwood Road to be completed this week and part of next week.

At its deepest point, Lake Needwood is about 20 feet, he said.

Frank said the information surveyors collect will be used to design the much-needed dredging project, which was recommended by the county Planning Board and County Executive Isiah Leggett (D) in the fiscal 2009 to 2014 Capital Improvements Program.

The project is expected to cost about $3.8 million and the County Council will make final funding decisions in May.

Parts of the lake, including a reservoir that catches sediment before it gets into the main body of water, were regularly dredged until about 1990, when the practice was discontinued because of funding constraints.

A buildup of silt since then is contributing to poor water quality and limiting boating and fishing, parks officials said.

Megan LeBoon, an engineering associate with F.X. Browne Inc., the Landsdale, Pa., company hired to handle the dredging project, told the Planning Board on Dec. 6 that the goal is to remove 100,000 cubic yards of sediment.

Lake Needwood was formed by an earthen dam in the 1960s for flood control and recreational use.

Rainstorms in June 2006 caused a rapid rise of the lake’s water level — which peaked nearly 25 feet above normal — and the dam started leaking on June 27 of that year. About 2,200 downstream residents were evacuated until the leaks were stabilized.

The lake receded three days later and the leaking stopped. Repairs to the dam are under way and should be completed by the middle of March, Frank said.

The dredging company will remove the sediment buildup with backhoes and bulldozers before hauling it away, LeBoon said.

She said the plan is to dump the sediment in an area between Beach Drive, Needwood Road and the path of the proposed Intercounty Connector to create a berm to buffer Rock Creek Regional Park from the highway.

When the dredging occurs, Lake Needwood would be lowered at a rate of six inches per day to allow the sediment to dry, as recommended by the Maryland Department of the Environment.

Frank said the level to which the lake will be lowered is comparable to ‘‘the low point that was hit last year during the drought.”

He said the drop will be most apparent near Needwood Road.

After the survey work is done, the speed at which Lake Needwood refills will depend how much it rains, he said.

The surveying is being done now rather than in the spring or summer to minimize the impact on recreational lake users, he said.

If the County Council gives it the green light, dredging would likely begin in October 2010 and be completed by March 2011.