Question: Which 6.8 mi tributary empties into the Potomac River at the Marine Corps Base Quantico's Air Station near Triangle, Virginia?

Context paragraphs:
United States Marine Corps Recruit Training: United States Marine Corps Recruit Training (commonly known as "boot camp") is a 12-week program of initial training that each recruit must successfully complete in order to serve in the United States Marine Corps.  All enlisted individuals entering the Marine Corps, regardless of eventual active or reserve duty status, will undergo recruit training at one of the two Marine Corps Recruit Depots (MCRD): Parris Island, South Carolina, or San Diego, California.  Male recruits from the 8th, 9th and 12th recruiting districts (areas west of the Mississippi River except Louisiana, and including parts of Illinois, Indiana, Wisconsin and Michigan) are sent to MCRD San Diego.  All recruits from the 1st, 4th and 6th recruiting districts and all female recruits are sent to Parris Island.  Those desiring to become officers attend training at Officer Candidates School at Marine Corps Base Quantico in Virginia.

Breckenridge Reservoir: Breckenridge Reservoir is a small reservoir on Chopawamsic Creek in Prince William and Stafford counties, Virginia.  The reservoir's western shore is the Marine Corps Base Quantico and the eastern shore is a part of Prince William Forest Park, which is a unit of the National Park Service.  The reservoir is open to fishing along with a Virginia fishing license and Marine Corps Base Quantico permit.  Primitive campsites and a hiking trail are on the Prince William Forest Park side of the reservoir.  Reservoir storage volume is approximately 22,500,000 cubic feet (517 acre-feet) with a

Kopp, Virginia: Kopp is an extinct unincorporated community located in Prince William County, Virginia.  The town began in 1885 and consisted, at one time, of a country store, school, post office, and Bellehaven Baptist Church, and was the home to about 100 local farming families.  The town ceased to exist in 1942 when the federal government added about 50,000 acres (200 km²) to Marine Corps Base Quantico.  The land upon which the residents of Kopp lived was purchased in what came to be known locally as "The Taking".  It was located near the current town of Independent Hill on the western portion of the Marine Corps Base.  No town buildings remain standing, and the church was demolished in about 1945, but the Marine Corps Base has been required to maintain the cemetery on the church grounds.

Chopawamsic Creek: Chopawamsic Creek is a 6.8 mi tributary of the Potomac River in Prince William and Stafford counties, Virginia.  Chopawamsic Creek is formed by the confluence of the North and South Branches of Chopawamsic Creek and empties into the Potomac River south of Quantico at the Marine Corps Base Quantico's Air Station.  Breckenridge Reservoir lies at the stream's confluence with the North and South Branches.  Along with its North Branch, Chopawamsic Creek forms part of the boundary between Prince William and Stafford counties.  The North Branch flows through part of the Chopawamsic Backcountry Area in Prince William Forest Park.

3rd Civil Affairs Group: 3rd Civil Affairs Group (3rd CAG) is a civil affairs (CA) unit of the United States Marine Corps based at Naval Station Great Lakes, Illinois.  The Marine Corps assigns civil affairs as a primary military specialty for enlisted and additional specialty for officers.  The Marine Corps uses its own civil affairs doctrine and runs the Marine Corps Civil-Military Operations School at Marine Corps Base Quantico to train civil affairs Marines.

Marine Corps Gazette: Marine Corps Gazette is a professional journal for U.S. Marines founded in 1916 at Marine Corps Base Quantico for members of the United States Marine Corps.  Begun by then Col John A. Lejeune as the vehicle to launch the Marine Corps Association (MCA), the journal is known as "The Professional Journal of U.S. Marines".  Today the MCA continues to publish the "Gazette" alongside "Leatherneck Magazine".  The headquarters of the "Gazette" is in Quantico, Virginia.

Marine Corps Base Quantico: Marine Corps Base Quantico, also known as MCB Quantico, is a United States Marine Corps installation located near Triangle, Virginia, covering nearly 55148 acres of southern Prince William County, Virginia, northern Stafford County, and southeastern Fauquier County.  Used primarily for training purposes, MCB Quantico is known as the ""Crossroads of the Marine Corps"".

Marine Corps Base Hawaii: Marine Corps Base Hawaii (MCBH), formerly Marine Corps Air Station Kaneohe Bay and originally Naval Air Station Kaneohe Bay, is a U.S. Marine Corps facility and air station located on the Mokapu Peninsula of windward O'ahu in the City & County of Honolulu.  For census purposes, the area is demarcated as the Kaneohe Station census-designated place, with a population at the 2010 Census of 9,517.  Marine Corps Base Hawaii is home to Marines, sailors, their family members and civilian employees.  The United States Marine Corps operates a 7800 ft runway at the base.

Marine Corps Air Facility Quantico: Marine Corps Air Facility Quantico (MCAF Quantico) (IATA: NYG, ICAO: KNYG, FAA LID: NYG) is a United States Marine Corps airfield located within Marine Corps Base Quantico, Virginia.  It was commissioned in 1919 and is currently home to HMX-1, the squadron that flies the President of the United States.  The airfield is also known as Turner Field, after Colonel Thomas C. Turner, a veteran Marine aviator and the second director of Marine Corps Aviation, who lost his life in Haiti in 1931.

Marine Corps Air-Ground Museum: The Marine Corps Air-Ground Museum was located at Brown Field, Marine Corps Base Quantico, Quantico, Virginia.  It housed a wide variety of historic Marine Corps vehicles/tanks (both wheeled and tracked), equipment, artillery pieces and aircraft (both fixed wing (airplanes) and rotary wing (helicopters)) to trace the evolution and significance of the Marine Air-Ground Team.  It also contained several pieces of foreign equipment, such as a Soviet SU-76M self-propelled howitzer.  The museum closed on November 15, 2002, during the establishment of the National Museum of the Marine Corps.

Supporting paragraphs: Chopawamsic Creek Marine Corps Base Quantico
Answer: Chopawamsic Creek