Take away the Klamath Reclamation Project. Take away irrigation in the Sprague River Valley. Take away all agricultural water draws in the Klamath Basin.

How much water flowed in and out of the Basin before humans started channeling, diverting and storing it?

That's what a recently released report by the U.S. Bureau of Reclamation aims to answer. But the report, long sought by differing sides in the ongoing debate over Klamath water, doesn't go into specifics on how the flow was different.

“It would be more or less, depending on the water year,” said Cecil Lesley, land and operations chief for the Bureau's Klamath Falls office.

He said the report offers a model that scientists can put numbers into to determine what unimpaired flows in the Basin looked like.

“It's a tool. It's tool for everybody to use that we didn't have before,” Lesley said.

But it's not a tool one can just pick up. It takes training to use.

John Hicks, Bureau water conservation specialist, called the report a “highly technical tool.”

He said the model is complex because determining what natural flows were takes more than just subtracting what the Project draws.

Along with the Project and other irrigation, the report examines the impacts of fire suppression, juniper encroachment, beaver trapping and logging on water flows.

Now that that tool is forged, Hicks said federal scientists might use it in January to determine what natural flows were like.

Entitled “Natural Flow of the Upper Klamath River,” the 115-page report, with 160 pages of appendices, dissects what has changed flows through the Basin.

“The last vestige of predevelopment watershed conditions unaffected by agricultural development was probably gone by about 1960,” the report says.

Work on the report started in mid-2002, a few months after Dave Sabo became manager of the Klamath Project. Sabo asked federal scientists to determine what flows were like before agriculture in the Basin.

The first draft of the report, released in December 2003, showed water in the Basin used to get lower than it does now. A reorganized report was released in December 2004, and a workgroup then met three times over the past year, reviewing the report.

The workgroup included representatives from American Indian tribes on the lower and upper parts of the Klamath Basin, the state of Oregon and the Klamath Water Users Association.

Irrigators hope the report can be used by the federal government to help determine requirements of protected species in the Basin, said Greg Addington, water users executive director.

The group, which represents 1,400 water users, will have the report vetted by engineers to determine its potential impact on water supplies in the Basin.