Lake Needwood
| Lake Needwood | |
|---|---|
 Looking upstream from the dam in 2021 | |
  Lake Needwood  Lake Needwood | |
| Location | Derwood, Maryland |
| Coordinates | 39°07′16″N77°07′46″W/ 39.121238°N 77.129388°W |
| Type | reservoir |
| Primary inflows | Rock Creek |
| Primary outflows | Rock Creek |
| Catchment area | 12.8 sq mi (33 km2) |
| Basincountries | United States |
| Surface area | 75 acres (30 ha) |
| Water volume | 196×106US gal (0.00074 km3) |
| Surface elevation | 324 ft (99 m)[1] |
Lake Needwoodis a 75-acre (300,000 m2)reservoirinDerwood,Maryland,United States. Located east ofRockville,in the eastern part ofMontgomery County,it is situated onRock Creek.The lake was created by damming Rock Creek in 1965 with the goal of providingflood controland reducingsoil erosion.[2][3]Lake Needwood also protects thewater qualityof the creek by functioning as aretention basinto trapsedimentfromstorm-waterrunoff.
The lake is part ofRock Creek Regional Park.Visitors can rentpedal boats,rowboats,andcanoes,and a flat-bottompontoon boat,the Needwood Queen, is available for rides. Also, thepicnicareas surrounding the lake are popular locations for various events. Other park features include a visitors center and snack bar, hiking and biking trails,playgrounds,anarcheryrange and Needwood Golf Course. About one mile (1.6 km) southeast is Lake Needwood's sister lake,Lake Frank.
TheRock Creek Trailbegins at Lake Needwood and can be followed along the course of Rock Creek, ending at thePotomac RiverinWashington, D.C.
Lake Needwood Dam
[edit]
Lake Needwood is a Rock Creek impoundment formed by an earthen embankment, the Lake Needwood Dam. It is made of a 65-foot (20 m) high earthen dam built on a fractured rock foundation formed at the junction of theBoulder GneissandUpper Pelitic Schistgeological formations.[4][5]In addition to the Lake Needwood's principal spillway outlet, it has a 185-foot (56 m) wide emergency spillway originating between the Westside and the Rock Creek Trails. The dam was designed by the Natural Resources Conservation Service.[5]
The construction of the Lake Needwood Dam was complete in 1965. The dam is owned by the Maryland-National Capital Park and Planning Commission.[6]At the time of construction, only the right portion of the dam bottom was treated with grout, likely predisposing the structure to generate a concentrated seepage of water from the left abutment during the2006 Mid-Atlantic United States Flood.[5]In 2007–2008, the earthen dam underwent a $3 million repair project to install a grout curtain below the Lake Needwood Dam to decrease seepage through its rock foundation and to upgrade the outlet control tower.[7]
Habitat
[edit]Lake waters are inhabited bylargemouth bass,catfish,bluegill,crappie,andtrout.[8]With a license,fishingis permitted.[9]Lake Needwood serves as a temporary stop for many North American migratory birds. However, the shoreline vegetation and soil integrity have been affected by non-migratoryCanada geeseprompting efforts to control their population.[10]
History
[edit]Mid-Atlantic United States flood of 2006
[edit]
There have been several evacuations of downstream residents during periods of heavy rain, due to concerns about the structural integrity of theearthen damconstructed in 1965. Thelatest evacuation,of approximately 2,400 people, was on June 28, 2006.[11]Communities just south of the lake were evacuated and were housed in temporary shelters at nearby high schools until the lake's level dropped. Theevacueeslived in 500apartmentsat the Rock Creek Terrace complex on Veirs Mill Road in Rockville and in 700single family homesin that area. Officials stated that the lake was 25 feet (8 m) above its normal level during the flood, and manyroadsin the surrounding area had been closed down for fear offlooding.As the flood subsided, evacuees returned home on June 29, 2006.Montgomery CountyHomeland SecuritydirectorGordon Aoyagiand CountyChief Administrative OfficerBruce Romer estimated that if the dam had broken, areas south of the lake could have flooded up to 19 feet (6 m).[12]
2010–2011 dredging project
[edit]Until 1990, the county government regularly conducteddredgingprojects of the lake to remove accumulated sediment. Dredging was then deferred for budgetary reasons. In 2008, the County started preparations to dredge sediment from the lake during 2010-2011. The dredging project aimed to improve water quality, as well as boating and fishing conditions.[13]
In October 2010, the water level was lowered by about six feet to allow more time for the sediment to dry out for dredging.[14]The shallower north end of the lake was deepened from 1 to 4 feet (0.30 to 1.22 m) deep to 12 to 18 feet (3.7 to 5.5 m) deep. The lake was reopened in summer 2012.[15]
Water quality
[edit]In 2010, lake waters tested positive formicrocystin,atoxinproduced bycyanobacteriathat can causeliverdamage.[16]The toxin was also reported in the water in 2012–2017[17][18]and in 2020.[19]Approximately 50 bright yellow signs are posted along trails around the lake advising patrons to keep pets away from the water.[20]
Cyanobacteria develop in the lake due to anoverabundance of nutrients(nitrogen and phosphorus) in the water. In residential areas, the nutrients are generated by excessivefertilizeruse and associatedurban runoff, which causeharmful algal blooms(HABs) in water bodies. Higher water temperature and low circulation are contributing factors.[21][22]
See also
[edit]- Rock Creek (Potomac River)
- List of parks in the Baltimore–Washington metropolitan area
- List of lakes in the Washington, D.C. area
References
[edit]- ^U.S. Geological Survey Geographic Names Information System: Lake Needwood
- ^"Park's Staff to Run Boat Concession At Maryland's New Lake Needwood".The Washington Post.October 6, 1966. p. C16.
- ^"New Montgomery Dam Creates 72-Acre Lake".The Washington Post.October 21, 1966. p. B1.
- ^"Heavy Rain Seepage Prompts Review and Retrofit of Lake Needwood Dam".Maryland Department of the Environment.RetrievedJanuary 7,2018.
- ^abcDalal, Visty P."Lake Needwood Dam Incident - A Geological Twist!"(PDF).Association of Environmental & Engineering Geologists.Archived(PDF)from the original on January 26, 2018.RetrievedJanuary 7,2018.
- ^"Heavy Rain Seepage Prompts Review and Retrofit of Lake Needwood Dam".Maryland Department of the Environment.RetrievedJanuary 7,2018.
- ^"Department of Parks Completes Construction on Lake Needwood Dam - Montgomery Parks".Montgomery Parks.June 2, 2008.RetrievedJanuary 7,2018.
- ^"Lake Needwood Boats".Montgomery Parks.RetrievedJanuary 7,2018.
- ^"Home Page".Maryland Department of Natural Resources.RetrievedJanuary 7,2018.
- ^"Living with Geese".Montgomery Parks.RetrievedJanuary 7,2018.
- ^Van Aller, Harold. "Dodging the Bullet: Lessons Learned From Recent Dam Emergencies".Maryland Department of the Environment.
- ^"Rain Sets Records, Causes Huge Problems".WTOP.] June 26, 2006. Archived from the originalon June 26, 2006.
- ^Gazette Newspapers."Lake Needwood to be lowered."February 13, 2008.
- ^"Department of Parks Starts Lowering Water Level in Lake Needwood in Preparation for Dredging".Montgomery Parks.Retrieved20 May2019.
- ^Singer-Bart, Susan."Boaters and Fishermen Rediscover Rockville Gem".Rockville Patch.Retrieved20 May2019.
- ^Liu, Mimi (2010-08-11)."Harmful algae bloom found at Lake Needwood in Derwood".The Gazette.Rockville, MD. Archived fromthe originalon 2018-01-08.
- ^Chotiner, Melissa (2014-07-22)."Montgomery Parks Reports Elevated Microcystin Levels at Lake Needwood; Visitors Asked to Use Caution".Silver Spring, MD: Montgomery Parks. Archived fromthe originalon 2018-01-08.
- ^"Montgomery Parks warns lake visitors about elevated levels of algae toxin".WTOP.Washington, DC. 2017-07-25.
- ^"Montgomery Parks Reports Signs of Microcystin at Lake Needwood; Visitors Asked to Use Caution".Montgomery Parks. 2020-08-08.
- ^Lewis, Kevin (2014-07-23)."Toxic algae in Montgomery County's Lake Needwood poses pet danger".WJLA.Washington, DC.
- ^"Harmful Algal Bloom Basics".Atlanta, GA: U.S. Centers for Disease Control and Prevention. 2020-06-03.
- ^"Causes of CyanoHABs".Cyanobacterial Harmful Algal Blooms in Water Bodies.Washington, DC: U.S. Environmental Protection Agency. 2019-07-17.