WASHINGTON - Wyoming members of Congress came out swinging Tuesday against a proposal by Sen. Max Baucus, D-Mont., requiring a minimum water flow into the Big Horn River to protect its trout fishery.

Escalating an ongoing dispute between the two states over the issue, Montana's other members, GOP Rep. Denny Rehberg and Democratic Sen. Jon Tester, pledged their support for Baucus's bill.

Baucus introduced legislation Tuesday that would set a preferred flow of 2,500 cubic feet per second from Yellowtail Dam and a minimum rate of 1,500 cfs. It would also require the Bureau of Reclamation to manage the Big Horn water system as a unit.

A Bureau of Reclamation official said that if the water flow had been maintained at Baucus's preferred rate instead of the current 1,500 cfs, lake levels would have dropped too low for power generation. But Montana fisheries biologists say the lower level hurts fish numbers.

Rep. Barbara Cubin, R-Wyo., strongly criticized the legislation.

"To introduce such an inflexible bill when this issue is right in the middle of careful negotiations between federal, state and local parties is simply bad policy," she said. "I am still hopeful that Montana and Wyoming can work together to find a solution that makes sense for both of our states, but it doesn't look like Sen. Baucus is interested in such a good-neighbor approach."

Sen. Craig Thomas, R-Wyo., also disagreed with Baucus's proposal.

"Mandating a river's water flow during a drought doesn't sound like a workable solution," he said. "If we're looking for a creative answer, it's not going to come from putting Montana's water needs ahead of Wyoming's. Bighorn Lake and the Big Horn River are both part of a water system that supports recreation and natural resource needs on either side of the state line."

Thomas said he wants to talk with Baucus about a solution that works for both states.

"But a one-sided solution is not an option," he added. "I won't let another state determine what happens with Wyoming's water. I'm convinced we'll need Mother Nature to cooperate to find our real solution, but until then we'll have to find an answer that works for both states."

Thomas, who just this month took a seat on the Senate Environment and Public Works Committee, said issues like this one will come before the panel and that he wants to find common ground through the regular legislative process.

Sen. Mike Enzi, R-Wyo., will discuss the issue with people in Wyoming, said spokesman Coy Knobel.

"This bill was written with Montana in mind," Knobel said. "Sen. Enzi will want to look at the bill closer before commenting extensively, but he will approach the legislation from the standpoint of putting Wyoming interests at the forefront."

Because of ongoing drought, less water has been flowing into the lake and the river, leading to a clash between the two states. In Wyoming, the lake fills reservoirs and provides irrigation and recreation. But the river in Montana is home to a premier trout fishery.

Baucus held a town-hall-style meeting on the issue Sunday in Billings. He said low-water conditions in the river could hurt the fish population. He also said he wanted the Bureau of Reclamation to be more flexible in its thinking and understand that the economic benefits of the river far outweigh the benefits of the lake.

In a statement Tuesday, Baucus said maintaining adequate flows in the Big Horn River "speaks to the soul and pads the wallet." He said fishing on the river generates more than $30 million in economic activity every year.

"The Big Horn is a lifeline for southeast Montana," Baucus said. "This river is internationally known as one of the best trout streams on the globe. We will not stand by and let it be dewatered. Montana has given enough."

Baucus's bill would allow the flow to be dropped below 1,500 cfs in case of emergency, such as flooding below the dam, or if lake levels get so low it would stop power generation.

The bill also states that one purpose of the Yellowtail Dam is for the maintenance of a healthy fishery on the Big Horn River. Currently, the dam is authorized for flood control and power generation.

The legislation also requires the bureau to coordinate management of all of its reservoirs in the Big Horn watershed.

Low water flow can affect fish in the river. State fish biologists in Montana say that when water flow drops below 2,500 cfs, young trout have less habitat and a lower chance of survival, and that rates below 1,500 cfs could be devastating.

The Bureau of Reclamation plans to keep the water flow at its current 1,500 cfs until at least spring, said Lenny Duberstein, head of the planning and project development division of the agency's Montana Area Office.

If the water flow had stayed at Baucus's preferred rate, the lake levels would have dropped too far to generate power, he said.

"If we had maintained the 2,500 cfs, then we would be basically to the bottom of our conservation pool at the end of January," Duberstein said. "At that point we'd be forced to stop power generation because the water levels would be too low."

If conditions become extreme, depending on snowpack and rain, the levels could be dropped below 1,500 cfs, he added.

The bureau plans no spring rise unless current conditions change significantly, he said. This drought is the worst on record, he added.

The Bureau of Reclamation is trying to work with the two states to look at the interests and resources from a broader perspective and come up with innovative solutions, Duberstein said. The agency hopes to have kickoff meetings next month with officials from several federal agencies, the two states, Big Horn County in Wyoming and the Crow tribe, he said.