CHEYENNE - Local governments in southwestern Wyoming will have a role in evaluating a private developer's proposal to build a pipeline to take water from the Green River, a U.S. senator said Wednesday.

Sen. John Barrasso, R-Wyo., said Wednesday he's secured "cooperating agency" status for Sweetwater County, the Sweetwater County Conservation District and the cities of Rock Springs and Green River. The status means the local governments will work with the U.S. Army Corps of Engineers in reviewing Colorado entrepreneur Aaron Million's pipeline proposal.

Million has applied to divert 250,000 acre feet of water from the Green River in Wyoming. An acre foot is about 325,000 gallons - the amount of water that would cover an acre to a depth of one foot.

Million plans to pipe the water through a multibillion dollar pipeline to Colorado's Front Range.

Million has said he's considering scaling back his application, but hasn't done so yet. He's emphasized that he's committed to building an environmentally sensitive project that won't hurt the river.

Sweetwater County, Rock Springs and Green River have all come out strongly against the pipeline proposal. They have said they're concerned about its likely effects on fishing and recreation and have agreed to pool money to oppose the project.

Hank Castillon, mayor of Green River, said Wednesday that his city and the other local governments will likely remain opposed to Million's project even if he reduces the amount of water he's seeking.

"It really doesn't make any difference whether he wants to publicly change it to 50- or 60,000 acre feet," Castillon said. "Once you start moving that water - this is my opinion - the appetite won't be quenched at that time. Once you get the camel's nose, things are going to start going."

Castillon said his city and the other local governments got the run-around when they first asked the Corps of Engineers for cooperating agency status. He said they learned last week from Barrasso that the agency has agreed to allow them to participate.

"We asked for it, and part of the reason for this is that we'll be granted the opportunity to sit at the table where the decisions are being made, instead of (participating) in writing, or responding to questions," Castillon said.

Rena Brand, project manager for the Corps of Engineers in Littleton, Colo., said Wednesday that her agency followed federal guidelines in deciding which agencies to invite to participate as cooperating agencies.

The corps hadn't acted on the local governments' requests to participate in the study until the senator got involved, Barrasso spokesman Greg Keeley said Wednesday.

Monday was the deadline for public comments on what issues the environmental study should address. Brand estimated her agency received 1,500 comments and said a draft study should be completed in 2012.

In addition to the local governments, the Corps of Engineers has invited the states of Colorado, Wyoming and Utah, 32 American Indian tribes and many other local, state and federal entities to participate.

Million said Wednesday he welcomes the participation of Sweetwater County, Green River and Rock Springs as participating agencies. He said they have issues of concern that need to be addressed.

"I think given the scope of the project, it's a reasonable approach without question," Million said.