Steve Rentfrow says Blackshear Dam a speed bump during major rain event

ALBANY — As the Flint River’s only dam north of Albany and south of Macon, the Lake Blackshear Dam gets a lot of attention when the water starts to rise. No one knows this better than Crisp County Power Commission General Manager Steve Rentfrow.

The Crisp County Power Dam is not big and Lake Blackshear is shallow — not a good combination for a major rain event such as the floods of 1994, 1998 and a smaller less intense events such as the one which occurred last Christmas.

“When that water heads south down the Flint there’s not much we can do about it … we’re really just a speed bump in the river,” Rentfrow told the Dougherty County Kiwanis Club on Monday. “We have 14 floodgates that when open can release water at 45,000 cubic feet per second (CFS). That is the limit of what we can do. Once the discharge reaches that point all we can do is sit back, watch and wait like everybody else.”

Rentfrow says people downriver often ask him if he can close the flood gates, which he said would do more harm than good.

“If the water tops the floodgates, the gates will fail,” he said. “That’s what happened in 1994 despite with all 14 gates open, the gates failed, the spillway dam washed out and Lake Blackshear was drained of all of its water. Southwest Georgia is flat and that’s a very shallow lake. Most people don’t realize there is only two feet of difference between the lake and river levels at the dam.”

Rentfrow then gave the sequence of events at the dam during December’s flood.

“From Dec. 23 to 30, rainfall of as much as nine inches fell in the Flint watershed, primarily at Macon and above,” Rentfrow said. “The initial forecast for peak at Montezuma was 45,000 CFS. A day later the new peak was revised to 55,000 CFS and we began gradually opening the flood gates.

“A day later the forecast was revived upward to 70,000

Lake levels dropped 5.4 feet at the dam before it stabilized and began rising, reaching 1.5 feet below normal pool. A second rain event projecting three to six inches locally was issued, but was not as great as forecast. Flow through the gates actually peaked at 55,000 CFS and the second rain event was not as great as forecast.”

“If the flow had been 70,000 CFS then the lake would have gone above normal pool, the gates remained open and the lake went down three feet,” Rentfrow said. “Once the river crest went through we gradually closed the gates and returned the lake level to normal. We closed the last gate on Jan. 12.

“If water ever goes through the dam it’s coming to Albany. It has no place else to go.”

Rentfrow added water going through the dam will cause a problem, the bigger contributors to flooding in Albany and further downriver are the Kinchafoonee and Muckalee creeks.

“Those are very big creeks and they move a lot of water. They are almost like small rivers,” he said. “But the only thing I know for sure is that it will happen again.”