Lake Needwood

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Lake Needwood
Lake Needwood.JPG
May 2006
Location Derwood, Maryland
Coordinates 39°07′16″N 77°07′46″W / 39.121238°N 77.129388°W / 39.121238; -77.129388Coordinates: 39°07′16″N 77°07′46″W / 39.121238°N 77.129388°W / 39.121238; -77.129388
Type reservoir
Primary inflows Rock Creek
Primary outflows Rock Creek
Catchment area 12.8 sq mi (33 km2)
Basin countries United States
Surface area 75 acres (30 ha)
Water volume 196,000,000 US gal (0.00074 km3)

Lake Needwood is a 75-acre (300,000 m2) reservoir in Derwood, Maryland just east of Rockville, in the eastern part of Montgomery County that is located on Rock Creek. The lake was created to provide flood control. It also protects the water quality of the creek by functioning as a retention basin to trap sediment from stormwater runoff. Ironically, there have been several evacuations of downstream residents during periods of heavy rain, due to concerns about the structural integrity of the earthen dam constructed in 1965.

The lake is part of Rock Creek Regional Park. Visitors can rent pedal boats, rowboats, and canoes, and a flat-bottom pontoon boat, the Needwood Queen, is available for rides. With a license, fishing is permitted. Also, the picnic areas surrounding the lake are popular locations for various events. Other park features include a visitors center and snack bar, hiking and biking trails, playgrounds, an archery range and Needwood Golf Course. About one mile (1.6 km) southeast is Lake Needwood's sister lake, Lake Frank.

The Rock Creek Trail begins at Lake Needwood and can be followed along the course of Rock Creek, ending at the Potomac River in Washington, D.C.

Mid-Atlantic States flood of 2006[edit]

Crews shoring up the Needwood Dam

The latest evacuation, of approximately 2,200 people, was on June 28, 2006. Communities just south of the lake were evacuated and were housed in temporary shelters at nearby high schools until the lake's level dropped. The evacuees lived in 500 apartments at the Rock Creek Terrace complex on Veirs Mill Road in Rockville and in 700 single family homes in that area. Officials stated that the lake was 25 feet (7.6 m) above its normal level during the flood, and many roads in the surrounding area had been closed down for fear of flooding. As soon as fears subsided, evacuees returned home on June 29. Montgomery County Homeland Security director Gordon Aoyagi and County Chief Administrative Officer Bruce Romer estimated that if the dam had broken, areas south of the lake could have flooded up to 19 feet (5.8 m).[1]

Dredging project[edit]

Until 1990, the county government regularly conducted dredging projects of the lake to remove accumulated sediment. Since that time dredging was deferred for budgetary reasons. In 2008, the County started preparations to dredge sediment from the lake during 2010-2011. The dredging project will improve water quality, as well as boating and fishing conditions.[2]

Lake Needwood Warning by Sonya Burke lake needwood for slider 450x280Montgomery Parks officials are asking residents to use caution when recreating on or near Lake Needwood.

Testing has shown there are elevated levels of microcystin, a toxic substance produced by some species of blue-green algae (cyanobacteria), in the 75-acre lake.

Microcystin, hepatoxin, can cause harm to the liver of humans and pets. Of particular concern are dogs that are off-leash and may swim and/or drink from the lake, despite park regulations.

Montgomery Parks officials are asking visitors to take the following precautions:

• Keep dogs on leash (as is regularly required at the park), and do not allow them to drink or go in the water • Swimming is prohibited in the lake at all times • Wash hands thoroughly if they come in contact with the water • Only eat properly cooked muscle meat of fish that are caught in the lake

Officials said boating and fishing will remain open at the lake.

“We have posted signs around Lake Needwood and urge visitors to please pay attention to these precautions to avoid any harm from microcystin,” said Jai Cole, Natural Resources Manager for Montgomery Parks. “Portions of the lake may be contaminated for the rest of the season. We will continue to monitor and update signs when the warning is lifted.”

For updates or more information, visit also==


  1. ^ "Evacuated Montgomery Co. Residents Go Home." June 30, 2006.
  2. ^ Gazette Newspapers."Lake Needwood to be lowered." February 13, 2008.