The environmental movement has taken three bad beatings in Congress in the last five days and should reorganize to impress its views more forcefully on the legislators, a Carter environmental adviser said yesterday.

In all three cases, said Gustave Speth, chairman of the Council on Environmental Quality, presidential vetoes "would have to be seriously considered and would be appropriate."

At a news conference, Speth cited three legislative actions; Senate approval last Friday of a provision put forward by Sen. Dale Bumpers (D-Ark.) to make it easier for courts to overturn federal regulatory decisions; Senate amendments Tuesday to a strip-mining bill that allow states to disregard Interior Department rules, and approval by both houses of the Tellico Dam in Tennessee, which would flood valuable farmland as well as the habitat of an endangered fish, the snail darter.

Speth said, "The environmental movement has fallen behind in getting itself politically organized in a more sophisticated and powerful way," despite strong support for environmental issues in public opinion polls.

"The environmentalists have no institution comparable to COPE," he said. COPE, organized labor's Committee on Political Education, organizes voter registration drives and raises money for labor-approved candidates. The League of Conservation Voters, a group that rates members of Congress on their environmental votes, is just a beginning, he said.

Speth said that environmental issues command strong grass-roots support around the country, and he cited House passage of the Alaska lands protection bill as an example. But because of other antienvironmental votes, he said, "Maybe some members of Congress are going to be in for an awakening when they go to the polls in the next election."

The Bumpers amendment, he said, "would completely reverse the time honored presumption that agency rules are valid. It is easy enough already to throw out agency rules.

"The Bumpers amendment would throw the whole regulatory process into disarray, making it impossible for the government to protect civil rights and all the other things government is supposed to do."

The Senate's "gutting of the stripmine law" this week, while it was done in the name of energy, would not make more coal available, Speth said, because demand, not supply, is limiting production. The strip-mine law requires companies to restore and replant land they have stripped.

In the case of the Tennessee dam, he said, the costs of flooding the land greatly exceed the dam's benefits. He added that "Congress established a process to review conflicts with endangered species and then turned around and abandoned the process after it was set in motion." Under that process, a Cabinet-level committee decided recently it was uneconomical to build the dam.

Asked why President Carter has not supported environmental issues as publicly as he has energy issues, Speth said, "Right now the country needs and is demanding more presidential attention on the energy issue and on inflation."