Salmon Restoration Effort On Trinity River Mired In Complexity (Part 2)

Jun 2, 2017

Seventeen years have passed since federal officials agreed to restore salmon populations on the Trinity River to levels unseen since it was dammed in the 1960s. Results have been slow. Last week we reported on the frustrations of some locals. Today, in part two, Marc Albert looks into why scientists think success hasn’t been obvious.

Cutting a rambling path from the Scott Mountains, the Trinity River eventually joins the storied Klamath before reaching the Pacific. For eons, the rivers’ abundant salmon sustained a vibrant civilization. A gold rush, intensive logging and integration with California’s agricultural irrigation system changed everything.

Brandt Gutermuth, a Bureau of Reclamation Environmental Scientist said hydraulic mining, drag line dredging and boat dredging---three successive methods for gold mining---left the soil layers upside down.

“When you pick it up with these bucket line dredgers, the big boats, all the dirt falls to the bottom” Gutermuth said.

Top soil was buried beneath mine tailings. As the river cut through it, the seasonal floodplains adjacent to the river, critical to young fish, wound up high and dry, blocked by what look like levees. Beginning in the 1960s, dams captured and diverted winter and spring floods.

Initially, scientists thought a fix would be simple: Plow openings in these berms of mine tailings with heavy equipment — release a series of strong surges from Trinity dam and let the river do the heavy lifting.

Turns out, that method didn’t work.

“It’s not just nicking the berm, it’s lowering floodplains and then creating habitat that will function,” Gutermuth said.

Now the heavy lifting is done by people. It’s more intense, more time consuming and more expensive. 

“We need to move that, move   those tailings and mining debris so excavate 10 to 20 feet down and they you have to move that out of the floodplain…because [otherwise] the river won’t connect to the habitat we’re creating,” he said.

Brandt Gutermuth, an Environmental Scientist with the US Department of Interior’s Bureau of Reclamation describes some of the work involved in restoring a floodplain buried beneath hundreds of tons of rock left by gold mining.
Credit Marc Albert

On adjacent hillsides, rusted mining debris, including hydraulic pipeline remnants, cables, tanks and cans aren’t hard to find, despite decades of nature being left to reclaim the landscape.

Down at the river’s edge where this summer’s construction will occur, sunlight glistens off the water while grasses wave in the breeze. Shiny clumps of poison oak and blackberries as thick as concertina wire soak up the sunlight.

“One of the things that we’re trying to do is to create this diversity of habitats where there’s a deep hole in proximity to a riffle, so that fish can be holding in the hole and feeding on the eddy line,” Gutermuth said. “So that, that’s the kind of stuff in managed rivers that is not, not as common.”

As the program drags on, some area residents are grumbling.

Along with the noise, dust and elapsed time salmon remain scarce. Critics note that the salmon population has risen by just 1 percent.

While that may be true in the strictest sense, the figure doesn’t represent the full picture. A graph provided by Mike Dixon, implementation branch chief for the Trinity River Restoration Program, shows estimates of out-migrating young salmon rising and falling like a roller coaster. Generally, the population soars in wet years, and plummets during droughts.

During the 1997-98 El Nino, estimates rose to nearly 1.5 million young hatched in the river from about 200,000 the year before. In 2005, the figure jumped to 2.5 million. The figures are based on young caught in traps near the confluence with the Klamath. Eight years after work began, the figure soared over 5 million. Then, the recent drought began and numbers fell off a cliff.

While the true measure of success involves the number of adults returning to spawn, the work does nothing for the fish during the three years they spend in the ocean. Predators and fishing take a heavy toll. Environmental phenomena such as El Nino or last year’s warm water blob can leave young salmon with little to eat.

“There are all these different things that will stop the adults from coming back that aren’t related to our work here. We could get it exactly right and the adults get harvested, Gutermuth said.

Even in a healthy fishery, only one in a thousand eggs return as spawning adults.

Hope remains. Gutermuth said last year’s construction, with its man-made beaver dam and purposeful log jams, appeared to get it right. 

“We constructed this side channel, we opened the side channel and within an hour, we had fish spawning in there," he said. "So, it’s immediate use, but yeah, the reality is that those fish have to go out to the ocean, they have to survive ocean conditions, so really a better metric of our success is how many juveniles go to the ocean.”

Like anywhere change occurs some are concerned or frustrated. Others, like Dave Shuman, who owns property near a popular local fishing spot where work is scheduled to occur this summer, are willing to wait and see.

“When restoration first come in, they had some blunders,” Shuman said. “They did some things that didn’t work out. People were upset. But, I think they’ve learned from their mistakes, and what they’re doing now hopefully will improve the fishing. I know I’ve talked to some of the guides and they’ve had, they said that this last year for steelhead was a really good year. So, that must tell you something. So, anyway, like I said, I have confidence in what they’re doing until they prove me wrong.”