Georgia wants the Corps of Engineers to further reduce the amount of water flowing out of Lake Lanier for metro Atlanta's needs, a request that's alarmed the city of Atlanta, downstream communities and environmentalists.

In a letter sent this week, state Environmental Protection Division Director Carol Couch asked the corps to keep an additional 130 million gallons of water a day in the federal reservoir, "in order to preserve valuable storage in Lake Lanier for future use during this exceptional drought."

That's enough water to serve the city of Atlanta, Sandy Springs and most of south Fulton.

But if the corps complies, that's also how much water won't be flowing down the Chattahoochee River past the pipes used to withdraw water for Cobb, DeKalb and Fulton counties and the city of Atlanta. That water also won't be available to dilute millions of gallons of treated sewage discharged daily by the region.

Couch has requested the lower flows through April 30. After that, water demands increase and water quality begins to worsen as temperature rise.

Couch said EPD evaluated the request and determined the river will still have a sufficient amount of dissolved oxygen to protect water quality through the end of April.

Corps spokeswoman Lisa Coghlan said Thursday the federal agency is still evaluating the request.

Rob Hunter, commissioner of Atlanta's Department of Watershed Management, said Couch's request caught him off guard.

"We are the last intake in that segment [of the Chattahoochee] and if someone's going to have a problem it's going to be us," Hunter said Wednesday. "It would have been nice to have a conversation before [the request] was sent to the corps."

Hunter's main concern is the city's intake pipe, which withdraws water from the Chattahoochee to serve more than 1 million people in the city, most of south Fulton and the Sandy Springs area. To pull sufficient water from the river, the pipe needs to be submerged at all times. If the river is too low, it could interrupt Atlanta's supply.

EPD spokesman Kevin Chambers said the state took Atlanta's intake pipe into account when it made the request to the corps. He said the state's calculations show that even with less water in the Chattahoochee, the river's surface should be at least seven feet above the intake pipe at all times.

It's been more than 30 years since the state set the current standard, measured in the Chattahoochee at Peachtree Creek, an urban stream that meets the river in northwest Atlanta. Peachtree Creek is downstream from where the metro Atlanta communities withdraw water from the river, and near where Cobb and the Atlanta discharge their treated sewage.

The minimum flow requirement is a safeguard to protect the river and downstream users from pollution.

Pat Stevens, chief environmental planner for the Atlanta Regional Commission, a planning agency for metro Atlanta governments, has been asking the state for months to waive the minimum flow requirement to conserve water. Stevens said the requirement is needed in the summer months, when the river's temperature rises and the level of dissolved oxygen plummets, but can be lowered in the winter and was during the droughts in the 1980s and in 2001.

"This is the absolute right time of the year to do it," Stevens said. "Lanier right now is the lowest it's ever been in February...The state's taking the right approach...There won't be harm to aquatic resources nor to downstream lakes."

Lanier, metro Atlanta's main water source, is still 14.5 feet below its average level for this time of year, a time when it should be refilling.

In a teleconference call Thursday with the corps, metro Atlanta communities, downstream communities and representatives from Florida and Alabama, Couch said her office had contacted the affected utilities that morning. She said she would work with them to make sure their concerns are heeded.

During the call, LaGrange Mayor Jeff Lukken said his community was "surprised and alarmed" by Couch's request. LaGrange pulls its water from West Point Lake, which is on the Chattahoochee downstream from metro Atlanta. In years past, the lake has been degraded by this region's pollution, including raw sewage spills.

"This is an environmental flow that's been in existence for 33 years," Lukken said.

Lukken called the timing "ill-conceived." On the one hand, he said Gov. Sonny Perdue wants local governments to allow people to fill swimming pools and water their lawns, but on the other, the state is trying to cut the amount of water flowing downstream to his community to bolster Lanier.

"We're concerned about the science and analysis done on this," Lukken said.