A debate in Congress over how to solve the Klamath Basin’s water battles led Wednesday to a discussion about what constitutes good science and revising the Endangered Species Act.

At a sometimes testy hearing of the House Resources Committee, Re-publicans said the Endangered Species Act now lets the federal government make decisions that may not be based on ‘‘sound science.’’ Some called for more peer review and better scientific justification for natural resource decisions.

The Republicans pointed to a recent National Academy of Sciences report about the Klamath Basin, which concluded that the science didn’t back up the government’s decision to cut off water to farmers last year in order to protect threatened and endangered fish in the region.

Rep. Wally Herger said the water was taken based on the ‘‘speculation’’ of federal biologists.

‘‘This situation is the poster child for the need to update the Endangered Species Act,’’ said Herger, a Republican whose district includes Modoc and Siskiyou counties. ‘‘How much balance (is there) when they get zero water?’’

Environmentalists and some Democrats, who were not allowed to invite witnesses to the hearing, have questioned the validity of the National Academy of Sciences report, suggesting that the academy asked the wrong question.

They say rather than looking at whether the government cut off water based on adequate science, the academy should have asked if the government used the best available science, as required under the Endangered Species Act.

‘‘In many cases, we have little science because these species are so rare,’’ said Susan Holmes, endangered species policy expert for Earthjustice. ‘‘We can’t wait for perfect science.’’

William Lewis, chairman of the National Academy of Sciences’ committee on endangered and threatened fishes in the Klamath Basin, stood by the academy’s report.

“We evaluated the scientific elements of the biological opinions, considered documents and testimony, and put our consensus opinion in the report,” he said. “We found that the recommendations on water levels weren’t well enough supported.”

He explained that experts, kept anonymous so they can speak freely, reviewed the report and the committee dealt with each point the reviewers raised to ensure completeness and accuracy.

“We haven’t precluded the possibility that someone could prove that the water levels are needed,” he said. “Scientific matters of this type are never finally settled.”

Lewis said, however, the government needs to take actions recommended years ago for the fish, including installing fish screens to cover irrigation canals and removing a dam to allow better fish passage.

‘‘We’re hung up on issues related to water management,’’ Lewis said.

Rep. Greg Walden, whose district takes in the Klamath Basin on the Oregon side, has offered legislation that would hold the government to a higher scientific standard before making endangered species decisions. He said Congress should consider changing the Endangered Species Act to require peer review and other new standards no matter what happens in the Klamath Basin.

‘‘That is a separate issue,’’ he said.

Tensions were high last year in the Klamath Basin when a drought left farmers, ranchers, fishermen, tribes and environmentalists fighting for a short supply of water. The Bureau of Reclamation, which runs an irrigation network serving 240,000 acres, had to sharply reduce deliveries to farmers to protect endangered sucker fish and threatened coho salmon.

Some farmers and anti-government protesters broke open the head gates to the irrigation canals on Independence Day to release a trickle of water.

The water problems are hardly isolated to the Klamath, though. Rep. George Miller, R-Calif., said people across the country, including the Central Valley in California, have water disputes that must be solved.

‘‘It is happening over and over again as we get competing uses for this water,’’ Miller said. ‘‘You cannot make a decision in the West and think it confined to that basin, or that river, or that reservoir.’’