The US Army Corps of Engineers Mobile District released a draft plan last week that will reduce the minimum amount of water flowing through the Chattahoochee River in Atlanta to 650 cubic feet per second (cfs). The new minimum flow, the lowest amount of water dam operators and other authorities must leave in the river to allow for withdrawals, dilute runoff, promote recreation, and support wildlife, will apply from November to April once the proposal becomes final. The current minimum flow is 750 cfs year round.
The USACE’s move comes as part of an update to its Water Control Manual for the Chattahoochee River. As part of the process of updating the manual, Georgia regulators asked the USACE to lower the minimum flow in Atlanta.
The Georgia Department of Natural Resources decided in August to remove a footnote from state regulations that had been understood to require a 750 cfs minimum flow on the Chattahoochee River, measured near its confluence with Peachtree Creek. During a meeting discussing whether to remove the footnote, one DNR Board member suggested that Georgia should keep as much water as it can while it has the water.
The reduced flow could allow authorities to hold more water in Georgia’s Lake Lanier.
Property owners and outfitters who operate on the river have opposed the move, worrying what effect reduced flows might have on property values and whether a lower flow could safely support recreation.
Environmentalists have cautioned that reducing the minimum flow could carry a number of negative consequences, including jeopardizing the Chattahoochee’s status as a trout stream and creating a human health hazard because of the lower capacity reduced flows would have to wash out pollutants from industry, sewers, and other sources.
The proposed reduction will go into effect some time after a 60 day public comment period. The complete plan, related documents, and information on commenting are available here.