(CNN) -- One image was clear -- a dead orca calf being carried across the ocean by its apparently grief-stricken mother. The calf may well have died from malnutrition. The Southern Resident Killer Whales in its pod are facing a critical shortage of their main food source: fat, juicy salmon.
The distressing scene repeated itself again and again over the course of more than two weeks in the summer of 2018 as the mother orca refused to let her baby go. But the bigger picture of how to help the whales get more salmon is far more complex and has opened new battles as well as old wounds.
At the heart of the row in the Pacific Northwest is whether to smash through the dams on the Snake River, a major tributary of the Columbia, that have changed the landscape and the ecosystems over the past decades.
"Historically the estimates are about 17 million salmon would return to the Columbia every year. It was the greatest salmon fishery in the world," says Brett VandenHeuvel, executive director of Columbia Riverkeeper.
"And now it's about a million fish return. So, we've declined dramatically from the historic levels."
In days gone by, young chinook salmon were swept downstream to the ocean by fast-flowing rivers. They'd fatten up over several years and while many fed human and animal hunters, millions would swim back upstream to cooler river waters to spawn the next generation, again providing nutrition and nutrients along the way to bears and eagles and also to the forests.
After the dams were built, gushing rivers became massive mill ponds of reservoirs, slowing the young salmon's journey to the sea. And when he wanted to return, that salmon was faced by crashing turbines and towering concrete walls barring his way to his birthplace, where nature dictates he should reproduce.
If you add in global warming to heat the now-slower waterways to a temperature too high for the chinook, you have a combination ready to make the situation even worse, VandenHeuvel fears.
Since the 1980s, federal programs have spent more than $16 billion on more fish-friendly designs and habitat restoration in the Columbia River Basin but it hasn't been enough to move 13 local species of salmon and steelhead off the endangered species list.
And now that global warming is impacting those slower waterways at an alarming rate, VandenHeuvel fears the entire salmon ecosystem is in hot water, with no relief in sight.
"Now that the river is so warm and getting hotter and hotter every year with climate change, we're afraid those numbers are just going to crash," he says.
For VandenHeuvel, the solution is clear -- remove the dams to allow nature to regain more of a foothold in this region. The argument is not a new one, but it has resurfaced in connection with the dwindling orca population.
But the dams have many supporters, too. They were installed to tame the rivers, provide water for agriculture and make the waterways navigable by barge to carry the huge harvests of wheat to market -- and those needs remain.
And though they were built at a time when coal and other fossil fuels were most certainly king, they also create clean hydropower, generating electricity without burning any carbon.
That's why Washington Gov. Jay Inslee, who put tackling climate change at the heart of his run for the Democratic nomination for president, rejects breaching the dams. He told CNN in a statement that hydropower is just too important to the region to tear the dams down.
Instead, the federal agencies that run the dams have tried various mitigations including fish ladders, where salmon that are equipped to leap up and over rapids can jump their way up steps until they are over the dam, while the turbines can still pump out clean power.
VandenHeuvel says it's time for environmentalists and officials to look beyond carbon.
"There are, there's a lot of things we've tried over the years, to help bring back salmon runs, and it's not working. And one of the big problems is the water is too hot. Water is too hot. So spilling more water or doing different things like that doesn't cool down the temperature of the Columbia river," he says.
"It's hard to call hydropower a clean energy any more, when it's driving salmon to extinction."
But while there's agreement that water that's too warm is bad for salmon, there are differences on where the heat is a problem.
Jason Sweet, a fish biologist with the Bonneville Power Administration, a federal agency that captures and markets hydropower in the Pacific Northwest, says the problems are not in the rivers that have been dammed.
"We're still seeing ocean conditions driving salmon numbers lower than we'd like right now."
Those ocean conditions include marine heatwaves or an unusually warm patch of water moving through the Pacific that was dubbed "The Blob" by Nick Bond, a research scientist and climatologist at the University of Washington and affiliated with the National Oceanic and Atmospheric Administration.
Bond's colleague, Rich Zabel, the fish ecology division director at the Northwest Fisheries Science Center, agrees that the heat in the oceans where the salmon get strong and fat enough to breed -- and feed orcas -- is a factor.
"I think we really have a chinook salmon issue more than specifically a dam issue," he says.
"Up and down the coast, chinook salmon have been doing poorly, and they're the main food source for orcas and so orcas aren't doing well, either." But other types of salmon, such as sockeye, are not doing as poorly, he notes.
Warm ocean water can affect the food sources for the salmon and deficits there will have impacts up the food chain.
"We're still recovering from the 2015 blob, and now there's potentially another marine heat wave," Zabel says. "If they come every three years, by the time a population recovers, they're being stressed again. So I think populations can rebound ... but we need some good ocean conditions and sustained good ocean conditions to get populations recovered to a level where we can do things like harvest."
Wilbur Slockish Jr., hereditary chief of the Klickitat Tribe, looks out across the land that was once so full of wildlife that it spawned names like Orcas Island and Salmon River. His grandfather was the last head of a tribe to sign a treaty ceding their lands to the federal government in 1855. That agreement said the exclusive right to fish in the area would stay with the Native Americans.
But Slockish says that if he wants his grandchildren and future generations to fish as their ancestors did, it may well take much more than just breaching the dams and letting the water flow free again.
"Everything in this world is connected, from the water, to the animals, to the plants, to the fish, to the people because they take care of each other," he says. "And when you disrupt one, you break that chain."