Rogue River Dam Blindsides Salmon

How a 'fish-friendly' dam in Oregon inadvertently set up a clash between spring and fall Chinook runs.

THE ROGUE RIVER in Southwestern Oregon, like most rivers in the west, has had lots of dams built on it to serve many purposes. Dams supply irrigation for farms in dry seasons and control flooding in wet seasons. Then there’s the promise of hydropower to energize homes and industries. But even the best-designed dams have unintended consequences on the natural world around them — especially on salmon.

photo of Lost Creek dam
The Lost Creek dam was billed as a fish-friendly project, but it's had unintended impacts on Rogue River salmon populations. Photo by US Army Corps of Engineers.

The history of dams on the Rogue — and their impact on salmon — stretches back more than 150 years. The river’s first dams were constructed by miners in the mid-1800s — creating reservoirs of water for hydraulic mining and to divert water in order to expose the streambed — for extracting gold from the hillsides and river bottoms. These structures, along with the sediments from hydraulic mining and pollution from gold extraction, caused massive die-offs of salmon. Later, more dams were built to water crops, transport logs, control floods, and produce hydroelectric power. Over time, hundreds of dams and other obstructions blocked fish passage on the Rogue and its tributaries. Salmon populations, once thriving, dwindled.

In 1977 the first “fish-friendly” dam was built on the Rogue. It was meant to provide the benefits of a dam while improving water quality and mitigating the impacts on struggling fish. However, despite the forethought that went into its construction, the dam has had significant unforeseen effects, essentially setting up a clash between the two distinct runs of spring and fall Chinook salmon in the river.

LOCALS AROUND MEDFORD, OREGON know it as the Lost Creek Dam, but officially, it is now the William L. Jess dam, renamed in honor of one of the founders of the Rogue Basin Flood Control and Water Resource Association. Jess bought a farm in the Rogue River valley in 1952, and saw firsthand the impact of flooding on the farming community after heavy rains. A strong advocate for the construction of a dam to control flooding, he approached the Army Corps of Engineers (USACE) for help.

At the time, however, there was a lot of opposition to a new dam on the river. In the early 1900s, a group of citizens had dynamited the Ament Dam on the Rogue because it was blocking salmon passage upstream. And in the 1940s, the Izaak Walton League, a national conservation organization, had resisted the construction of the Lewis Creek Dam, just four miles downstream from the current location of the Lost Creek Dam. The project’s effects on salmon became such an emotional issue the government dropped the idea like a hot potato. In 2000, Jess’s brother, Bud, recalled the sentiment in an interview, “Trying to talk about a dam on the mainstem of the Rogue River was anathema to many…”

But in December 1964, an Arctic front spread south, bringing chilled air over the valley. After the ground froze hard, a blizzard hit and dumped a foot of snow over the region. A “Pineapple Express” followed, carrying five days of hard rain. The snow melted, but the ground was still frozen — the water had no place to go except to run across the surface. This combination of heavy rain and snowmelt flooded the valley and took out every bridge from Prospect to Gold Hill. The flood, considered the most severe to ever occur over Central Oregon, gave the Rogue Basin Association momentum to push the new dam forward. It would protect the downstream communities while flooding the less-politically connected villages above it.

The Lost Creek Dam is 159 miles upstream from the mouth of the 215-mile long Rogue River. Today, the dam is the last one standing on the mainstem of the river (eight others have been removed or modified in the last decade, and salmon have benefitted as a result.) It is 327 feet high with two hydro-powered electric generators. A cooling tower controls the temperature of the water flowing from the dam — releasing cool water and increasing the dry-season flow.

In theory, this feature would make vast stretches of the mainstem of the Rogue livable year-round for coldwater species like trout and salmon. (This was considered to be especially important since decades of logging had removed the shading effects of trees in the watershed.) Because of this, even though there’s no fish ladder allowing salmon passage upstream beyond the Lost Creek Dam, it was sold as “good for the fish.”

AT ITS HEADWATERS, the Rogue filters down through lava channels under the collapsed caldera of Crater Lake, emerging from basalt rock at the base of Mt. Mazama at a constant 37 degrees. Before the dam was built, the water would have warmed considerably by the time it reached the mouth of the river. In late summer and, the water temperature could exceed 75 degrees — lethal for salmon. Fall-run Chinook had to wait in the ocean for autumn rains to cool the river’s temperature.

Before the dam went in, the spring Chinook took advantage of high April-June water levels to run upstream and spend summers in the cool water near the headwaters. They remained in the upper Rogue until spawning in September. The fall-run Chinook historically spawned about a month later, in the lower stretches of the river. There was relatively little overlap in time or space between the runs.

photo of rogue river
At its headwaters, the Rogue filters down through lava channels under the collapsed caldera of Crater Lake, emerging from basalt rock at 37 degrees. Photo by Ray Bouknight.

But the Lost Creek Dam changed the environment for Chinook salmon, says Greg Taylor, a biologist with USACE.

The dam’s release of cool water in summer roughly doubles the river’s flow, allowing fall Chinook to enter the river earlier in September and travel farther upstream, to areas they hadn’t used heavily to spawn before. As a result, the fall run of Chinook, which is 99 percent wild, is very healthy. Fall-run Chinook in the upper Rogue have increased dramatically (about five-fold), which has been linked to the construction of the Lost Creek Dam.

Steve Beyerlin, a river guide and former Legislative Director for the Oregon Guides and Packers, believes that the Lost Creek Dam has been beneficial to fish. “Putting the dam in was a win-win situation,” he says.

Perhaps not for spring-run Chinook, though.

Brian Barr, a biologist with the Rogue River Watershed Council, a non-profit stewardship organization, told Earth Island Journal that the spring-run Chinook, the most highly-prized fish on the river (because of their large size and high fat content), decreased dramatically after the dam’s installation. Spring Chinook returns dropped from a historic level of about 30,000 naturally produced adult fish (from 1946-1980 when spring Chinook were likely already depleted compared with pre-development levels) before the Lost Creek Dam, to a 10-year average of about one-fourth that number in 2007. Returns improved to about 10,000 fish in 2017 (likely due to dam removals, river restoration projects, water flow alterations, and harvest management restrictions), giving managers some cause for optimism.

The dam closes access to about one third of the river’s prime spawning grounds for spring-run Chinook salmon. And for the past four decades, the quickened fall run has overlapped with the spring Chinook, disrupting their egg nests because they spawn in similar places. What’s more, the dam’s release of warmer water in winter causes the early-spawning spring Chinook eggs below the dam to hatch prematurely, before insects in the river are available for them to feed on —resulting in drastically lowered survival rates.

In an attempt to mitigate the dam’s effects on the spring Chinook population, engineers built the Cole Rivers Hatchery at the foot of the dam. Like most topics involving Pacific salmon, this is a controversial one. Many biologists are concerned about the effects of hatchery fish on wild salmon populations like Rogue spring Chinook. Jim Lichatowich, a salmon biologist and author of Salmon Without Rivers, says, “It’s like copying a famous painting. A good painter can copy a masterwork so it looks like the real thing. But in doing so, you’ve lost the creative process. Likewise [with hatchery fish], the creative ecological process can’t be duplicated.”

Even hatchery enthusiasts such as Beyerlin admit that hatchery mitigation for the loss of spring Chinook habitat isn’t working correctly. The survival of hatchery smolts to the adult stage, when they return to the river, is critically low. Although 1.7 million juveniles are released into the river every year, hatchery-produced spring Chinook numbers have been declining to only 3,000-4,0000 returns in recent years. One reason for this, Beyerlin says, is that the insect populations that feed juvenile spring Chinook are now lower than before the dam went in, possibly caused by changes in the sediments the insects need as habitat that get trapped behind the dam.

Another perhaps more ominous complication is the loss of genetic diversity caused by this overlap of wild spring and fall Chinook spawning. Researchers at the University of California, Davis have found that fall and spring Chinook have different versions of a gene linked to migration timing, and the spring-type gene has declined in frequency since the Lost Creek Dam was installed. The early spring Chinook genotype risks being lost forever.

In spite of our best intentions, altering the physical foundation of an ecosystem has unintended consequences. Anything we do takes from one community to benefit another. River and fisheries managers now juggle managing stream flows and harvest rates to balance impacts on various user groups and the health of the resources themselves. As USACE biologist Taylor put it, “Every time you touch the dial there is a cascading effect on some part — and not just what you are focused on.” In the case of the Lost Creek Dam, even though engineers tried to divine the ecological consequences of its construction, the spring Chinook salmon were lost in a blind spot.

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