Lake Needwood is a

reservoir A reservoir (; ) is an enlarged lake behind a dam, usually built to water storage, store fresh water, often doubling for hydroelectric power generation. Reservoirs are created by controlling a watercourse that drains an existing body of wa ...

in Derwood,

Maryland Maryland ( ) is a U.S. state, state in the Mid-Atlantic (United States), Mid-Atlantic region of the United States. It borders the states of Virginia to its south, West Virginia to its west, Pennsylvania to its north, and Delaware to its east ...

, United States. Located east of Rockville, in the eastern part of Montgomery County, it is situated on Rock Creek. The lake was created by damming Rock Creek in 1965 with the goal of providing

flood control Flood management or flood control are methods used to reduce or prevent the detrimental effects of flood waters. Flooding can be caused by a mix of both natural processes, such as extreme weather upstream, and human changes to waterbodies and ru ...

and reducing

soil erosion Soil erosion is the denudation or wearing away of the Topsoil, upper layer of soil. It is a form of soil degradation. This natural process is caused by the dynamic activity of erosive agents, that is, water, ice (glaciers), snow, Atmosphere of Ea ...

. Lake Needwood also protects the

water quality Water quality refers to the chemical, physical, and biological characteristics of water based on the standards of its usage. It is most frequently used by reference to a set of standards against which compliance, generally achieved through tr ...

of the creek by functioning as a

retention basin A retention basin, sometimes called a retention pond, wet detention basin, or storm water management pond (SWMP), is an artificial pond with vegetation around the perimeter and a permanent pool of water in its design. It is used to manage ...

to trap

sediment Sediment is a solid material that is transported to a new location where it is deposited. It occurs naturally and, through the processes of weathering and erosion, is broken down and subsequently sediment transport, transported by the action of ...

from storm-water runoff. The lake is part of Rock Creek Regional Park. Visitors can rent pedal boats, rowboats, and

canoes A canoe is a lightweight, narrow water vessel, typically pointed at both ends and open on top, propelled by one or more seated or kneeling paddlers facing the direction of travel and using paddles. In British English, the term ''canoe'' ca ...

, and a flat-bottom

pontoon boat A pleasure boat with two lengthwise pontoons A pontoon boat is a flattish boat that relies on floats to remain buoyant. These pontoons (also called ''tubes'') contain much reserve buoyancy and allow designers to create large deck plans fitted w ...

, the Needwood Queen, is available for rides. Also, the

picnic A picnic is a meal taken outdoors (Al fresco dining, ''al fresco'') as part of an excursion, especially in scenic surroundings, such as a park, lakeside, or other place affording an interesting view, or else in conjunction with a public event su ...

areas surrounding the lake are popular locations for various events. Other park features include a visitors center and snack bar, hiking and biking trails,

playground A playground, playpark, or play area is a place designed to provide an environment for children that facilitates play, typically outdoors. While a playground is usually designed for children, some are designed for other age groups, or people wi ...

s, an

archery Archery is the sport, practice, or skill of using a Bow and arrow, bow to shooting, shoot arrows.Paterson ''Encyclopaedia of Archery'' p. 17 The word comes from the Latin ''arcus'', meaning bow. Historically, archery has been used for hunting ...

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 The Potomac River () is in the Mid-Atlantic (United States), Mid-Atlantic region of the United States and flows from the Potomac Highlands in West Virginia to Chesapeake Bay in Maryland. It is long,U.S. Geological Survey. National Hydrography D ...

Washington, D.C. Washington, D.C., formally the District of Columbia and commonly known as Washington or D.C., is the capital city and federal district of the United States. The city is on the Potomac River, across from Virginia, and shares land borders with ...

Lake Needwood Dam

Lake Needwood is a Rock Creek impoundment formed by an earthen embankment, the Lake Needwood Dam. It is made of a high earthen dam built on a fractured rock foundation formed at the junction of the Boulder Gneiss and Upper Pelitic Schist geological formations. In addition to the Lake Needwood's principal spillway outlet, it has a wide emergency spillway originating between the Westside and the Rock Creek Trails. The dam was designed by the Natural Resources Conservation Service. The construction of the Lake Needwood Dam was complete in 1965. The dam is owned by the Maryland-National Capital Park and Planning Commission. 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 the 2006 Mid-Atlantic United States Flood. 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.

Habitat

Lake waters are inhabited by

largemouth bass The largemouth bass (''Micropterus nigricans'') is a carnivorous, freshwater fish, freshwater, ray-finned fish in the Centrarchidae (sunfish) family, native to the eastern United States, eastern and central United States, southeastern Canada an ...

catfish Catfish (or catfishes; order (biology), order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Catfish are common name, named for their prominent barbel (anatomy), barbels, which resemble a cat's whiskers, though not ...

bluegill The bluegill (''Lepomis macrochirus''), sometimes referred to as "bream", "brim", "sunny", or, in Texas, "copper nose", is a species of North American freshwater fish, native to and commonly found in streams, rivers, lakes, ponds and wetlands ea ...

crappie Crappies () are two species of North American freshwater fish of the genus ''Pomoxis'' in the family Centrarchidae (sunfishes). Both species of crappies are popular game fish among recreational anglers. Etymology The genus name ''Pomoxi ...

, and

trout Trout (: trout) is a generic common name for numerous species of carnivorous freshwater ray-finned fishes belonging to the genera '' Oncorhynchus'', ''Salmo'' and ''Salvelinus'', all of which are members of the subfamily Salmoninae in the ...

. With a license,

fishing Fishing is the activity of trying to catch fish. Fish are often caught as wildlife from the natural environment (Freshwater ecosystem, freshwater or Marine ecosystem, marine), but may also be caught from Fish stocking, stocked Body of water, ...

is permitted. 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-migratory

Canada geese The Canada goose (''Branta canadensis''), sometimes called Canadian goose, is a large species of goose with a black head and neck, white cheeks, white under its chin, and a brown body. It is native to the arctic and temperate regions of North ...

prompting efforts to control their population.

History

Mid-Atlantic United States flood of 2006

FEMA - 25162 - Photograph by Aaron Skolnik taken on 06-28-2006 in Maryland

There have been several evacuations of downstream residents during periods of heavy rain, due to concerns about the structural integrity of the

earthen dam An embankment dam is a large artificial dam. It is typically created by the placement and compaction of a complex semi-plastic mound of various compositions of soil or rock. It has a semi-pervious waterproof natural covering for its surface ...

constructed in 1965. The latest evacuation, of approximately 2,400 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

apartment An apartment (American English, Canadian English), flat (British English, Indian English, South African English), tenement (Scots English), or unit (Australian English) is a self-contained housing unit (a type of residential real estate) that ...

s at the Rock Creek Terrace complex on Veirs Mill Road in Rockville and in 700

single family home A single-family detached home, also called a single-detached dwelling, single-family residence (SFR) or separate house is a free-standing residential building. It is defined in opposition to a multi-family residential dwelling. Definitions ...

s in that area. Officials stated that the lake was above its normal level during the flood, and many

road A road is a thoroughfare used primarily for movement of traffic. Roads differ from streets, whose primary use is local access. They also differ from stroads, which combine the features of streets and roads. Most modern roads are paved. Th ...

s in the surrounding area had been closed down for fear of

flood A flood is an overflow of water (list of non-water floods, or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are of significant con ...

ing. As the flood subsided, evacuees returned home on June 29, 2006. Montgomery County

Homeland Security Homeland security is an American national security term for "the national effort to ensure a homeland that is safe, secure, and resilient against terrorism and other hazards where American interests, aspirations, and ways of life can thrive" to ...

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 .

2010–2011 dredging project

Until 1990, the county government regularly conducted

dredging Dredging is the excavation of material from a water environment. Possible reasons for dredging include improving existing water features; reshaping land and water features to alter drainage, navigability, and commercial use; constructing d ...

projects 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. In October 2010, the water level was lowered by about six feet to allow more time for the sediment to dry out for dredging. The shallower north end of the lake was deepened from deep to deep. The lake was reopened in summer 2012.

Water quality

In 2010, lake waters tested positive for

microcystin Microcystins—or cyanoginosins—are a class of cyanotoxins, which are toxins produced by cyanobacteria, sometimes known as blue-green algae. Over 250 different microcystins have been discovered so far, of which microcystin-LR is the most commo ...

, a

toxin A toxin is a naturally occurring poison produced by metabolic activities of living cells or organisms. They occur especially as proteins, often conjugated. The term was first used by organic chemist Ludwig Brieger (1849–1919), derived ...

produced by

cyanobacteria Cyanobacteria ( ) are a group of autotrophic gram-negative bacteria that can obtain biological energy via oxygenic photosynthesis. The name "cyanobacteria" () refers to their bluish green (cyan) color, which forms the basis of cyanobacteri ...

that can cause

liver The liver is a major metabolic organ (anatomy), organ exclusively found in vertebrates, which performs many essential biological Function (biology), functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of var ...

damage. The toxin was also reported in the water in 2012–2017 and in 2020. Approximately 50 bright yellow signs are posted along trails around the lake advising patrons to keep pets away from the water. Cyanobacteria develop in the lake due to an overabundance of nutrients (nitrogen and phosphorus) in the water. In residential areas, the nutrients are generated by excessive

fertilizer A fertilizer or fertiliser is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from liming materials or other non-nutrient soil amendments. Man ...

use and associated

urban runoff Urban runoff is surface runoff of rainwater, landscape irrigation, and car washing created by urbanization. Impervious surfaces (roads, parking lots and sidewalks) are constructed during land development. During rain, storms, and other Precipitati ...

, which cause

harmful algal bloom A harmful algal bloom (HAB), or excessive algae growth, sometimes called a red tide in marine environments, is an algal bloom that causes negative impacts to other organisms by production of natural algae-produced toxins, water deoxygenation, ...

s (HABs) in water bodies. Higher water temperature and low circulation are contributing factors.

References

{{DEFAULTSORT:Needwood, Lake Derwood, Maryland Reservoirs in Maryland Chesapeake Bay watershed Potomac River watershed Rockville, Maryland Lakes of Montgomery County, Maryland Tourist attractions in Montgomery County, Maryland