You might think twice about grabbing that Big Gulp before driving to Denver: The state is closing the Interstate 25 rest areas at Larkspur.

Colorado Department of Transportation officials had been thinking about closing the two rest areas since the southbound facility was closed in November because it would have needed $300,000 in repairs to meet state health department standards. Early this year, the department sought public comment on closing the rest areas, and most of those who responded didn't want the restrooms shuttered, said CDOT spokesman Bob Wilson.

Despite the comments, the decision announcing the permanent closures came Wednesday. The northbound rest area will close Monday.

"It wasn't an easy decision," said CDOT Regional Transportation Director Tony DeVito.

"Both areas have been used for many years by travelers and commercial drivers alike, but the facilities are outdated and require continual maintenance. The costs to keep both areas open are becoming prohibitive."

The department, which has seen large cuts in its budget the past few years, said it costs about $650,000 each year to maintain the rest areas. Wilson said it would have cost $12 million to rebuild the restrooms.

"You could build a lot of highway with that kind of money," he said.

Wilson said money wasn't the only issue. Both the Colorado State Patrol and the Douglas County Sheriff's Office have made arrests for drug dealing and prostitution at the rest areas, he said. The rest areas, nestled in pines atop a ridge, were designed in a way that makes on-site and video monitoring difficult.

The southbound rest area opened in 1968 and the northbound facility in 1974.

Wilson said the rest areas were built when Monument and Castle Rock were much smaller and offered fewer amenities to passing motorists. Those two towns and nearby Larkspur now offer places where motorists can stop for a restroom break.

The buildings at the rest areas will be torn down and closure gates will be installed. By October or November, the parking lots will be reconfigured and restriped to allow truckers to install or take off chains when the chain law is in effect on Monument Hill.

The areas will be gated except during those times, Wilson said.

With the closure of the rest areas, the closest northern rest area will be near Fort Collins and the closest southern facility near the El Paso-Pueblo county line.