Lake level forecast for March 2018 projecting a two foot drop
The lake has risen significantly over the past several weeks with rainfall in the right places for increasing inflows into Lake Lanier. In light of that, we have had a few members express surprise about the current lake level forecast for the next month. We thought we would post some information related to that issue.
Normal Corps ACF operations call for an increase in downstream discharges beginning on March 1, given current conditions in the ACF. That and expectations for the Southeast U.S. to return to drier-than-normal conditions are what combine in the Corps’ forecast for Lanier to drop by about two feet in the next month. Here’s the scoop:
Lake Lanier rose three feet in a week from 2/8-2/15, and is now 3.4 feet higher than it was a mere two weeks ago. We caught a big break last week with heavy rain in the upper ACF basin, especially in the headwater areas of the Chattahoochee and Chestatee Rivers. The Hooch peaked at over 6,000 cfs near Cornelia on the 11th and 12th, and the Chestatee peaked at over 5,000 near Dahlonega. Lanier’s inflows from the two rivers are currently running a little over 1,600 cfs, slightly above the 59-year mean for this day of the year.
Seven-day average ACF basin inflows are currently at 30,000 cfs and were over 40,000 from 2/11 through 2/18. ACF Conservation Storage is currently above the guide curve, meaning that cumulative reservoir levels are slightly above full winter pool. In particular, Lake Lanier is more than six inches above its full winter pool of 1070 MSL. The Corps’ ACF Water Control Manual calls for releases of any basin inflow above 5,000 cfs through the end of February. On March 1, basin inflows available for storage (i.e., water that can be kept in the reservoirs) will drop from everything over 5,000 cfs to 50% of inflows over 16,000. So, in order to accommodate threatened and endangered species such as the Gulf sturgeon, whose spawning period begins around April 1, spring flows will increase across the GA/FL starting next week.
The bottom line, as always, is that it takes normal spring rains throughout the basin to keep ACF lakes full into the coming recreation season.
Lake Lanier Association