Native American tribes have returned to Scotland to protest outside the headquarters of Scottish Power.
The fish stocks in the Klamath River have plummeted
Representatives from four tribes said that the firm's American subsidiary, PacifiCorp, operates dam projects which have led to a drop in salmon numbers.
A visit to Scotland last year won the tribes a commitment to find a solution. However, the company announced the sale of PacifiCorp to MidAmerican in May.
Scottish Power said it had no direct control over the hydro scheme.
The tribes said Scottish Power, which has its HQ in Glasgow, had stonewalled them with negotiations until they could find a buyer for the subsidiary.
'Moral thing to do'
They argued that because the sale would take up to 18 months to complete, Scottish Power bosses still had time to act.
The Karuk, Yurok, Hoopa and Klamath tribes said the dam development had devastated more than 350 miles of historic salmon spawning grounds on the River Klamath in California and Oregon.
The 15-strong delegation said there had been a huge decline of fish numbers in what was once America's third greatest salmon river.
Ron Reed, a Karuk tribal fishermen, said: "Removing these dams is both the moral thing to do, and the best economic choice for Scottish Power/PacifiCorp.
"The dams are old and inefficient and produce relatively little electricity. They are not vital for energy production, or agriculture.
"Their impact on our local environment and tribal cultural resources cannot be understated.
"And they threaten Scottish Power's image of being a responsible business that cares for the environment and communities."
The visitors called on the utility giant to make the decision to scrap the dams at the firm's annual general meeting on Friday.
A Scottish Power spokesman said: "As we said last year, the Klamath negotiations are a PacifiCorp issue that will be resolved in the US, and the proposed sale makes no difference.
"The Tribes have already met with MidAmerican and were assured that they will continue to deal with the same executives at PacifiCorp.
"Scottish Power has not had and will not have any direct involvement in the re-licensing process which, in any case, will ultimately be decided by the Federal authorities."