Last summer, the orca known as J35, also called Tahlequah, carried her dead calf for 17 days.

During those 17 days, the plight of the Southern Resident Orca Whales gained international attention, as people wondered what J35 was doing. Was she in mourning? Did she think her baby was still alive? How long would she carry her baby? What could we do to keep this from happening, and to save the southern residents?

But several years before this, orca advocates and researchers were already trying to answer the problems that the orcas face.

One problem in particular caught the eye of writer Steven Hawley: the salmon problem. Having done research on dams and how they affect salmon populations for his book, “Recovering a Lost River,” Hawley brought one chapter of his book to filmmaker and local documentarian Michael Peterson.

“The chapter was ironically titled, ‘Feed Willy,’” Peterson said. “It talks about the starving southern residents, who are starving because they can’t get enough of their main food source, Chinook salmon.”

Four years later, amidst the rising panic over the state of the southern resident orcas, Peterson and Hawley are releasing their film “Dammed to Extinction.” The first viewing of the film (“A sneak peek screening,” Peterson said) will be in Port Townsend at 3:45 p.m. on May 4, at the Wheeler Theater at Fort Worden.

Working with researcher Ken Balcomb from the Center for Whale Research in Friday Harbor, Peterson and Hawley created the film to educate people about the intensely political problem of dams on Pacific Northwest rivers.

Through his years of research, Balcomb found that the whales need roughly a million salmon each year to survive. But he also knows that salmon populations are declining.

The film explores one possible solution to this conundrum: remove four dams on the Snake River and return it to its state as the largest Chinook-producing river on earth.

But the issue of removing the dams is an intensely political one.

In Eastern Washington, the dams are viewed as a large part of the economy, producing electricity and helping to barge produce.

Peterson, who was born and raised in the Tri-Cities, is familiar with the issue.

“I understand the culture and the people,” he said. “My dad still has a place right on the Snake River. I think the biggest problem is just a lack of education about the dams.”

There are three major issues that the film addresses; asking if the dams are economically viable, if lack of barging would hurt local farmers, and whether irrigation of farms would be affected by taking out the dams.

“The power that is produced on those four dams is not needed here in our state,” Peterson said. “The dams actually lose money. What used to be a profitable thing has now become a money losing thing.”

Meanwhile, if the dams were removed, he said, bringing the Chinook run back would be a bigger salmon restoration effort than all of the other restoration projects combined.

“The film will be food for thought for everybody: politicians, orca advocates, energy industry professionals,” said Debra Ellers, an orca advocate with the North Olympic Orca Pod. “Whether people are for or against dam breaching, it’s a great experience to come see the film.”

Peterson, who has spent 20 years working in film and television in Hollywood, said the film is produced at a high quality with an original music score, graphics, and underwater footage, much of which was shot by local filmmaker Florian Graner, who lives on Whidbey Island.

The screening at Fort Worden will be part of the Global Earth Repair Conference, which is taking place May 3-5, highlighting a host of climate activists and researchers who will give presentations, classes and panel discussions.

The film screening is open to the public. It will include a discussion with the filmmakers at the end, and proceeds from the $10 tickets will go to the filmmakers as they begin to take their film around the Pacific Northwest for screenings.

To learn more about the film, visit dammedtoextinction.com.