WASHINGTON - The U.S. Army Corps of Engineers will update the manuals it uses to guide how Georgia and Alabama share water in a major river basin, agreeing to a long-sought demand from Georgia officials who say new data is necessary to account for their state's rapid growth.

While Georgians cheered the development, it angered Alabama officials who have fought to block the move, saying it could hurt the state's water supply. Both states have intensely lobbied Corps and Army officials in recent months as drought has gripped the region.

"It's been 17 years since they've been updated," said Sen. Johnny Isakson, a Georgia Republican. "It's old information. What's changed in the last 17 years is unbelievable."

Isakson and other Georgia lawmakers cautioned that the decision is only one of many the Corps must take to resolve the crisis.

For one thing, the update could take three years, according to Assistant Army Secretary John Paul Woodley. And the decision applies only to one of the state's main river basins - the Alabama-Coosa-Tallapoosa, which runs southwest through Georgia and Alabama.

"Georgia still faces a dire situation with regard to our short-term water supply," Sen. Saxby Chambliss said.

The manuals - which provide the core data on which sharing agreements are based - are a central front in a multi-pronged court battle that has raged in the region for almost two decades. Tensions have heightened as Georgia and Alabama have been hit with record dry spells this year.

The Corps' decision comes after a judge overseeing mediation between the states decided last month that talks had broken down.

Georgia has sought to hold back more water to boost the state's tight drinking supply. Alabama has fought them, arguing their plans would threaten Alabama's water security, damage the environment and stunt growth. Alabama officials fear updating the manuals would unfairly benefit Georgia, maintaining that the Corps has been focused on Atlanta's needs at the expense of communities downstream.

"I intend to support the legitimate interests of Alabama to the full extent," said Sen. Jeff Sessions, R-Ala. "Georgia is not entitled to capture all the upstream water and use it as they will. The natural flow of the river must be maintained."

Sen. Richard Shelby, R-Ala., who is sponsoring legislation to block the Corps from spending money on the updates, was similarly critical, calling it a "pointless exercise" that would only prolong the dispute.

Georgia lawmakers, meanwhile, said the new, more accurate data should pave the way toward an agreement.

They urged the Corps to make a similar decision to update manuals for the Apalachicola-Chattahoochee-Flint river basin, which runs through Florida and is the subject of a separate tri-state legal battle over the release of water from Atlanta-area reservoirs to comply with the Endangered Species Act.

In other water developments Thursday, the state of Alabama added new complaints to a water lawsuit it originally filed in 1990, filing papers in Birmingham challenging the government's recent decision to hold more water in Georgia's Lake Allatoona, which serves the Atlanta metro area and is in the Alabama-Coosa-Tallapoosa basin.

Neither the state of Georgia nor the Army Corps had responded to the new claims.

For its part, Georgia is preparing another lawsuit demanding that the Corps restrict water flow from federal reservoirs in the state after the federal government refused to immediately reduce the flow of water from lakes. The governor's office said the lawsuit will likely be filed on Friday.