The road across Elkhead Reservoir Dam officially closed Monday.
Construction crews closed and barricaded Moffat County Road 28 and diverted traffic to Routt County Road 78 so they can raise the dam by 25 feet.
Raising the dam will allow the reservoir to hold twice as much water as it did when crews began the expansion project in 2004.
When the $32 million expansion project is complete in 2007, the reservoir will hold 24,888 acre-feet of water. Before the expansion, the reservoir on the Routt and Moffat county line held 13,800 acre-feet of water.
The 1.2-mile stretch of Routt County Road 78 was submerged when Elkhead was built in the 1970s.
The road meets Moffat County Road 29, west of Elkhead.
Officials had planned to close Moffat County Road 28 last spring and begin diverting traffic to the Routt County road. But a late thaw meant crews had to wait.
Routt County Road 78 will be used until fall 2006, when Moffat County Road 28 opens again.
The speed limit on the two-lane dirt road is 25 mph.
For residents just east of Elkhead, the detour will add a few minutes to their trip to Craig.
Al Carroll, who lives in Routt County just east of the reservoir, said the detour would add about five minutes to his trips to Craig.
Carroll said his only concern about the detour is that the road is too steep where the detour meets Routt County Road 78.
"I think someone is going to be in the ditch there before the winter is over," he said.
Carroll expects to use the road about four times a week, he said.
In about two weeks, crews will stop expansion for the winter, officials said.
When crews would return to work is "up in the air," project manager Ray Tenney said.
Tenney is an engineer with the Colorado River Water Conservation District. The district oversees the Elkhead expansion project.
Ron Cloninger, chief resident engineer for URS Engineering of Denver, said crews will be right on schedule before they leave for the winter.
"We actually did more than we had planned," he said.
The outlet works, which allows water to drain from the reservoir into Elkhead Creek, will be near completion when crews leave next week, Cloninger said.
Crews hope to complete the outlet works in February in time for the spring runoff, he said.
Brandon Johansson can be reached at 824-7031, ext. 213, or firstname.lastname@example.org.