River Flow Rate at Medlock Bridge

The U.S. Geological Survey (USGS) operates and maintains the gaging station located on the Chattahoochee River at Medlock Bridge in cooperation with the the U.S. Army Corps of Engineers, Mobile District, and Georgia Power, under provisions of FERC regulations. The USGS operation of the water-quality monitoring related to the Chattahoochee BacteriALERT program is in cooperation with Cobb-Marietta Water Authority, the Cobb County Water System, and in partnership with the National Park Service and Chattahoochee Riverkeepers. The USGS Atlanta Field Office is responsible for the management of this station.

USGS Water-data graph for site 02335000

Daily fluctuations in the chart are due to water releases from Buford Dam.

For additional information about water temperature, precipitation, gage height, and turbidity at this location visit the USGS website at https://waterdata.usgs.gov/ga/nwis/uv?site_no=02335000.

Flood Levels

As the river level increases at a gaging station the risk for potent loss of life and property increases. Below are definitions for the different flood stages and the damage that can be expected.

  • Major Flood Stage - Expect extensive inundation of structures and roads. Significant evacuations of people and/or transfer of property to higher elevations becomes necessary.
  • Moderate Flood Stage - Expect some inundation of structures and roads near stream. Some evacuations of people and/or transfer of property to higher elevations becomes necessary.
  • Flood Stage - Expect minimal or no property damage, but possibly some public threat.
  • Action Stage - Flooding becomes a concern. River/stream is approaching or is forecast to approach the gage height - flood stage - where flooding is defined to begin. Flood stage is an established gage height for a given location at which a rise in water surface level begins to create a hazard to lives, property, or commerce.

Flood Categories for Medlock Bridge

Major Flood Stage: 20 ft.
Moderate Flood Stage: 16 ft.
Flood Stage: 12 ft.
Action Stage: 10 ft.

Historical Crests

  1. 27.70 ft on 01/08/1946
  2. 27.10 ft on 12/13/1919
  3. 27.10 ft on 12/10/1919
  4. 23.40 ft on 04/01/1886
  5. 22.20 ft on 04/07/1936

Low Water Records

  1. 0.05 ft on 08/25/1925
  2. 0.60 ft on 10/02/1925
  3. 1.51 ft on 09/26/2007

Visual Flood Impacts

27.7 ft. Major flooding inudates area. Many homes and roads submerged by flood waters. This is the peak flood crest of record which occurred on January 8, 1946.
24 ft. Major flooding expands. Flood waters will cover the road bed of Georgia Highway 141 Medlock Bridge
20 ft. Major flooding begins. Some homes will be submerged with flood waters.
16 ft. Moderate flooding begins. Extensive flooding of lowlands and access roads to the river will occur. Water will also begin to enter some homes.
12 ft. Flood Stage is reached and minor flooding begins. Flood waters will begin to cover Chattahoochee River National Recreation Area parking lot at Medlock Bridge Park. In addition...bottomland flooding increases in the flood plain.
10 ft. Water goes to the top of the boat ramp of the Chattahoochee River National Recreation Area.

USGS WaterAlert

The U.S. Geological Survey WaterAlert service sends e-mail or text (SMS) messages when certain parameters, as measured by a USGS real-time data-collection station, exceed user-definable thresholds. The development and maintenance of the WaterAlert system is supported by the USGS and its partners, including numerous federal, state, and local agencies. Subscribe to WaterAlert for this location.

Last updated: August 3, 2018

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1978 Island Ford Parkway
Sandy Springs, GA 30350


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