Go ahead and gulp down that extra glass of water, Gwinnett.

For the first time ever, Gwinnett County officially has the right to pull drinking water from Lake Lanier.

Home to nearly a million people, Gwinnett has used Lanier as a water source since at least the 1970s. But any associated arrangements with the U.S. Army Corps of Engineers, which controls the lake, have been informal — and also served as a battleground in the interminable “water wars” involving Georgia, Florida and Alabama.

That changed last week.

In a unanimous vote, Gwinnett’s Board of Commissioners approved an agreement with the state of Georgia that will legally grant it access to about 112 million gallons of Lanier’s water per day. The county currently uses only about 76 million gallons daily.

“This contract is the result of many years of work to gain access to adequate storage volume to secure water supply for the communities that depend on Lake Lanier for their drinking water,” Rebecca Shelton, Gwinnett’s interim water resources director, said in a news release.

The Gwinnett-specific deal — which will remain in place for at least the next three decades — was made possible early last year, when Georgia reach its own historic and hard-fought agreement with the Corps of Engineers. That contract officially granted the state rights to about 15% of Lake Lanier’s capacity.

At the time, one metro Atlanta official called the agreement “one of the biggest steps that we’ve experienced in securing our water future.”

The goal all along was for the state to subsequently contract with places like Gwinnett, Forsyth County and the cities of Buford, Cumming and Gainesville, which have long supplied residents with water drawn from the man-made reservoir.

Rights to Lanier have been a particularly thorny subject for Gwinnett officials, due to both the size of the county’s population and the government’s outsized efforts to be a good steward. Gwinnett’s wastewater treatment plants return tens of millions of gallons of water to Lake Lanier each day.

The allocation the county secured last week amounts to a little over half of the state’s total afforded volume.

“Quality water is important for our residents and visitors,” Commission Chairwoman Nicole Hendrickson said in a statement. “It is the small benefits that play a large part in why Gwinnett County is the preferred place to live and work.”

The county will pay about $1.5 million per year for its now formal water rights. It will also pay a proportional share of the state’s annual operations and maintenance costs at the lake, which this year are estimated at about $270,000.

Documents said the money will come from existing county water and sewer funds.

Gwinnett would also be on the hook for a share of any future repair or rehabilitation projects undertaken by the state.