Rock Creek is a free-flowing tributary

Tributary

A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...

 of the Potomac River

Potomac River

The Potomac River flows into the Chesapeake Bay, located along the mid-Atlantic coast of the United States. The river is approximately long, with a drainage area of about 14,700 square miles...

, which empties into the Atlantic Ocean

Atlantic Ocean

The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

 via the Chesapeake Bay

Chesapeake Bay

The Chesapeake Bay is the largest estuary in the United States. It lies off the Atlantic Ocean, surrounded by Maryland and Virginia. The Chesapeake Bay's drainage basin covers in the District of Columbia and parts of six states: New York, Pennsylvania, Delaware, Maryland, Virginia, and West...

. The creek

Stream

A stream is a body of water with a current, confined within a bed and stream banks. Depending on its locale or certain characteristics, a stream may be referred to as a branch, brook, beck, burn, creek, "crick", gill , kill, lick, rill, river, syke, bayou, rivulet, streamage, wash, run or...

 is 32.6 miles (52.5 km) long, with a drainage area

Drainage basin

A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...

 of about 76.5 square miles (198.1 km²). The last quarter-mile (402 m) of the creek is affected by tide

Tide

Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth....

s.

Geography

The creek rises from a spring near Laytonsville

Laytonsville, Maryland

Laytonsville is a town in Montgomery County, Maryland, United States. The population was 277 at the 2000 census. Laytonsville was originally known as Cracklintown. This name originated from the popular cracklin bread, which was baked in the locale. This recipe, essentially a bacon corn bread, also...

 in Montgomery County

Montgomery County, Maryland

Montgomery County is a county in the U.S. state of Maryland, situated just to the north of Washington, D.C., and southwest of the city of Baltimore. It is one of the most affluent counties in the United States, and has the highest percentage of residents over 25 years of age who hold post-graduate...

, Maryland

Maryland

Maryland is a U.S. state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware to its east...

, and joins the Potomac near Georgetown and the Watergate

Watergate complex

The Watergate complex is a group of five buildings next to the John F. Kennedy Center for the Performing Arts in the Foggy Bottom neighborhood of Washington, D.C. in the United States. The site contains an office building, three apartment buildings, and a hotel-office building...

 in Washington, D.C.

Washington, D.C.

Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....

 Beginning in the Derwood

Derwood, Maryland

Derwood is an unincorporated area of about 15,600 people in east-central Montgomery County, Maryland. It is a relatively dense area. It lies just east of Rockville, south east of Gaithersburg, south west of Olney, and north west of the greater Silver Spring, Maryland area. Residents of Derwood...

–Rockville

Rockville, Maryland

Rockville is the county seat of Montgomery County, Maryland, United States. It is a major incorporated city in the central part of Montgomery County and forms part of the Baltimore-Washington Metropolitan Area. The 2010 U.S...

 area in Maryland, the creek flows through
Rock Creek Regional Park southward to the D.C. boundary. About 9 miles (14.5 km) of the creek flow though Rock Creek Park

Rock Creek Park

Rock Creek Park is a large urban natural area with public park facilities that bisects Washington, D.C. The park is administered by the National Park Service.-Rock Creek Park:The main section of the park contains , or , along the Rock Creek Valley...

 in Washington, where it is fed by several small creeks — Piney Branch, Pinehurst Branch, Broad Branch, Soapstone Branch, and Luzon Branch — and numerous storm sewers

Storm drain

A storm drain, storm sewer , stormwater drain or drainage well system or simply a drain or drain system is designed to drain excess rain and ground water from paved streets, parking lots, sidewalks, and roofs. Storm drains vary in design from small residential dry wells to large municipal systems...

.

The Maryland portion of the watershed

Drainage basin

A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...

 comprises the second-largest watershed in Montgomery County, about 60 sq mi (155.4 km²). About 21 percent of the creek's watershed is in Washington. Total land usage in the watershed is 896 acre of wetlands or water, 22272 acre of residential and commercial areas, 15488 acre of forest or grasslands, and 10304 acre of agricultural areas. The creek has a fairly steep gradient, with rapid changes in elevation. The man-made Lake Needwood

Lake Needwood

Lake Needwood is a 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...

 is located on the creek, north of Rockville.

Water quality and restoration

In Maryland, most of the northern Rock Creek watershed has good to excellent water quality

Water quality

Water quality is the physical, chemical and biological characteristics of water. It is a measure of the condition of water relative to the requirements of one or more biotic species and or to any human need or purpose. It is most frequently used by reference to a set of standards against which...

, according to studies conducted by the county government. In 2004, to preserve water quality in partially developed areas, the county imposed restrictions on development

Land development

Land development refers to altering the landscape in any number of ways such as:* changing landforms from a natural or semi-natural state for a purpose such as agriculture or housing...

 (i.e., designation of a "Special Protection Area") in parts of this sub-watershed. The southern portion of the Maryland watershed is highly urbanized

Urbanized

Urbanized is a 2011 documentary film by Gary Hustwit released on 26 October 2011 and considered the third of a three-part series on design known as the Design Trilogy, the first being Helvetica about the typeface and the second being Objectified about industrial design.The documentary discusses...

. The majority of this portion of the creek and its tributaries has poor water quality. The county is managing several stream restoration

Stream restoration

Stream restoration or river restoration, sometimes called river reclamation in the UK, describes a set of activities that help improve the environmental health of a river or stream. Improved health may be indicated by expanded habitat for diverse species and reduced stream bank erosion...

 projects throughout the watershed.

The D.C. segment of Rock Creek also has poor water quality. In addition to typical urban stormwater

Stormwater

Stormwater is water that originates during precipitation events. It may also be used to apply to water that originates with snowmelt that enters the stormwater system...

 pollution

Water pollution

Water pollution is the contamination of water bodies . Water pollution occurs when pollutants are discharged directly or indirectly into water bodies without adequate treatment to remove harmful compounds....

 problems such as runoff

Surface runoff

Surface runoff is the water flow that occurs when soil is infiltrated to full capacity and excess water from rain, meltwater, or other sources flows over the land. This is a major component of the water cycle. Runoff that occurs on surfaces before reaching a channel is also called a nonpoint source...

 from streets and other impervious surface

Impervious surface

Impervious surfaces are mainly artificial structures--such as pavements that are covered by impenetrable materials such as asphalt, concrete, brick, and stone--and rooftops...

s, the creek has high bacteria

Bacteria

Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

 levels due to combined sewer overflows (CSOs). The D.C. government, which has a stormwater discharge permit issued by the United States Environmental Protection Agency

United States Environmental Protection Agency

The U.S. Environmental Protection Agency is an agency of the federal government of the United States charged with protecting human health and the environment, by writing and enforcing regulations based on laws passed by Congress...

, is improving its stormwater management to improve water quality in Rock Creek. In 2009, the District of Columbia Water and Sewer Authority

District of Columbia Water and Sewer Authority

The District of Columbia Water and Sewer Authority provides drinking water, sewage collection and wastewater treatment in Washington, D.C., USA. DC Water also provides wholesale wastewater treatment services to several adjoining municipalities in Maryland and Virginia...

 began a project to replace portions of the combined sewer with separate storm sewers. The project, which is expected to eliminate the CSO-related problems in the creek, is scheduled to be completed in 2011.

In 2006 the National Park Service

National Park Service

The National Park Service is the U.S. federal agency that manages all national parks, many national monuments, and other conservation and historical properties with various title designations...

 completed a project to remove or bypass eight fish barriers in the creek. Restoration activities included adding a fish ladder

Fish ladder

A fish ladder, also known as a fishway, fish pass or fish steps, is a structure on or around artificial barriers to facilitate diadromous fishes' natural migration. Most fishways enable fish to pass around the barriers by swimming and leaping up a series of relatively low steps into the waters on...

 to bypass the 1905 Peirce Mill Dam, modifying historic fords

Ford (crossing)

A ford is a shallow place with good footing where a river or stream may be crossed by wading or in a vehicle. A ford is mostly a natural phenomenon, in contrast to a low water crossing, which is an artificial bridge that allows crossing a river or stream when water is low.The names of many towns...

, and removing abandoned sewage

Sewage

Sewage is water-carried waste, in solution or suspension, that is intended to be removed from a community. Also known as wastewater, it is more than 99% water and is characterized by volume or rate of flow, physical condition, chemical constituents and the bacteriological organisms that it contains...

 lines and fords. The effort is designed to restore American shad

Shad

The shads or river herrings comprise the genus Alosa, fish related to herring in the family Clupeidae. They are distinct from others in that family by having a deeper body and spawning in rivers. The several species frequent different areas on both sides of the Atlantic Ocean, Mediterranean Sea....

, river herring

Alewife

The alewife is a species of herring. There are anadromous and landlocked forms. The landlocked form is also called a sawbelly or mooneye...

, and other migratory fish to the creek and their historic upriver spawning

Spawn (biology)

Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...

 grounds. It is estimated that 2 million fish migrate up the creek each year.

Tributaries

Tributaries of Rock Creek are listed in order from the mouth upstream.

In D.C.:

• Dumbarton Oaks
• Normanstone Creek
• Klingle Valley Creek
• Piney Branch
  Piney Branch
  Piney Branch is a tributary of Rock Creek, a free-flowing tributary of the Potomac River, which empties into the Atlantic Ocean via the Chesapeake Bay in the United States. It runs along Piney Branch Parkway, and joins Rock Creek at Piney Branch and Beach Drive in the Northwest quadrant of...
  
  
• Melvin Hazen Valley Branch
• Broad Branch
  • Soapstone Branch
• Luzon Branch
• Pinehurst Branch
• Fenwick Branch
  • Portal Branch

In Maryland:

• Donnybrook Tributary
• Coquelin Run
• Capitol View Tributary
• Kensington Heights Branch
• Stoney Creek
• Alta Vista Tributary (formerly Bethesda Run)
• Luxmanor Branch
• Stoneybrook Tributary
• Josephs Branch
• Turkey Branch
• Sycamore Creek
• Croydon Park Tributary
• Southlawn Branch
• North Branch (Lake Bernard Frank
  Lake Bernard Frank
  Lake Bernard Frank , is a reservoir on the North Branch of Rock Creek in Derwood, Maryland, United States, just east of Rockville. It is named after Bernard Frank, a wilderness activist and a co-founder of The Wilderness Society. The lake's boundaries are, approximately, Route 28, East Gude...
  
  )
• Lake Needwood
  Lake Needwood
  Lake Needwood is a 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...
  
   (in-line on Rock Creek)
• Crabbs Branch
• Mill Creek
• Pope Farm Branch
• Airpark Road Branch

See also

• List of rivers of Washington, D.C.
• List of rivers of Maryland
• Rock Creek and Potomac Parkway
  Rock Creek and Potomac Parkway
  The Rock Creek and Potomac Parkway, often known simply as the Rock Creek Parkway, is a parkway maintained by the National Park Service as part of Rock Creek Park in Washington, D.C...
  
  
• Tidewater Lock
  Tidewater Lock
  The Tidewater Lock is a dam in Washington, D.C. to the west of the mouth of Rock Creek at the Potomac River, on the east side of Georgetown. It is sometimes listed as Lock 0 on the Chesapeake and Ohio Canal....
  
  

External links

• Rock Creek Regional Park (Maryland)
• Friends of Rock Creek's Environment
• Countywide Stream Protection Strategy: Rock Creek Watershed Montgomery County Department of Environmental Protection