Big Creek at GA 9 near Cumming, GA

River level and flood forecast · Forsyth County

Normal-0.2 ftas of Mon 3:45 PM

The river is 6.2 ft below flood stage (6 ft).

Flow: 28 cubic feet per second (USGS).

The last 7 days and the forecast

NWS forecast issued Sun, Dec 31, 7 PM. Forecasts change as rain falls and as upstream water arrives.

Flood stages

Major flood stage	15 ft
Moderate flood stage	12 ft
Flood stage	6 ft
Action stage	4 ft
Record crest (September 22, 2009)	10.43 ft

What floods at each level

From the National Weather Service, highest first.

14 ftModerate flooding continues with significant flooding expanding further into the woodlands and pasture near the creek. The sidewalk and boardwalk of the Big Creek Greenway will be completely flooded out with several feet of water. Around two feet of water will be flowing over portions of the Atlanta Highway. This will likely cause a washout of the road near the culvert. The water level will also be reaching the bottom of the bridge on Majors Road.
12 ftModerate flooding begins with significant flooding expanding further into the woodlands and pasture near the creek. The sidewalk and boardwalk of the Big Creek Greenway will be completely flooded out with several feet of water. The water will begin flowing over portions of the Atlanta Highway. Extensive erosion of the banks near the culvert may cause a washout.
10 ftMinor flooding continues to expand further into the woodlands and pasture near the creek. The sidewalk and boardwalk of the Big Creek Greenway will be completely flooded out. The areas under the Georgia 400 Highway and McFarland Road will be covered with around five feet of water. A portion of the sidewalk under Majors Road will be covered with around six feet of water. Maximum flow will be reached through the culvert at Atlanta Highway and erosion of the banks near the bridge will begin.
8 ftMinor flooding will expand into the natural flood plain of the creek upstream and downstream from the gage at Atlanta Highway or Georgia Highway 9. Most of the sidewalk and boardwalk of the Big Creek Greenway will be under a foot or two of water. The areas under the Georgia 400 Highway and McFarland Road will be covered with around three feet of water. A portion of the sidewalk under Majors Road will be covered with around four feet of water.
7 ftMinor flooding continues to expand into the natural flood plain of the creek upstream and downstream from the gage at Atlanta Highway or Georgia Highway 9. Large portions of the sidewalk and boardwalk of the Big Creek Greenway will be flooded. The areas under the Georgia 400 Highway and McFarland Road will be covered with around two feet of water. A portion of the sidewalk under Majors Road will be covered with around 3 feet of water.
6 ftFlood stage is reached. Minor flooding will expand into the natural flood plain of the creek upstream and downstream from the gage at Atlanta Highway or Georgia Highway 9. Large portions of the sidewalk and boardwalk of the Big Creek Greenway will begin to flood. The areas under the Georgia 400 Highway and McFarland Road will be covered with around one foot of water. A portion of the sidewalk under Majors Road will be covered with around two feet of water.
5 ftBankfull conditions continue to expand into low lying areas of the creek upstream and downstream from the gage at Atlanta Highway or Georgia Highway 9. Portions of the sidewalk on the Big Creek Greenway under the Georgia 400 Highway and McFarland Road begin to flood. A portion of the sidewalk under Majors Road will be covered with around one foot of water. The water level will begin reaching the bottom of the boardwalk along several sections of the Greenway.
4 ftBankfull conditions are reached in some low lying areas of the creek upstream and downstream from the gage at Atlanta Highway or Georgia Highway 9. A small portion of the sidewalk on the Big Creek Greenway under Majors Road will begin to flood.

Highest crests on record

10.43 ft — September 22, 2009
9.15 ft — August 1, 2013
9.02 ft — October 11, 2020
8.86 ft — January 4, 2015
8.84 ft — January 4, 2023

Recent crests: 6.76 ft (February 27, 2026) · 6.06 ft (April 7, 2025) · 8.19 ft (February 13, 2025) · 6.09 ft (December 29, 2024) · 6.2 ft (December 11, 2024)

Up and down the river, and nearby

See it on the live map →Radar & warnings for Forsyth County NWS gauge page USGS gauge 02335580

Not an official source. River levels, forecasts, flood stages and impacts are from the National Weather Service (CMGG1); flow from the U.S. Geological Survey. Readings are provisional. In a flood, follow your local officials and the NWS at weather.gov.