water > features > breaking down the us salmon barriers
Breaking down the US salmon barriers
Posted: 27 Sep 2005
by Jamie Pittock
From its headwaters high up in the Cascade Mountains of south-west Oregon, the Rogue was a rich salmon river, meandering its way hundreds of miles to the Pacific Ocean. But unless some of its many man-made barriers are removed, it will never be restored to its former glory.
Out here in the rugged American north-west salmon is king, and the Rogue, together with its tributaries, provides crucial spawning habitat for several stocks of the commercially and recreationally prized fish species.
Rogue River, Oregon, US.
© WWF-Canon / Jamie Pittock
"Salmon are up against a mighty creek without a paddle as the Rogue River is plagued with a thousand barriers that impede fish migration," said Brian Barr, a fish ecologist with WWF’s Klamath-Siskiyou office in Oregon. "Breaking down some of those barriers will be critical to their survival."
A deadly race
Salmon have a complex life history that makes their survival truly remarkable. Young salmon migrate from rivers and streams to the ocean, spending as much as six years at sea before returning as mature adults — some reaching weights of 27kg. Once they migrate back to the rivers and streams of their birth, they spawn and then die.
While in freshwater, either as young or returning adults, salmon face a deadly race as summer approaches — evacuating the hot, lower river areas to the cooler tributaries and mountain streams (river temperatures need to be less than 13°C for spawning and egg incubation, while salmon will die if the water temperature tops 18°C for prolonged periods).
And, if this wasn’t enough to worry about, they also have to tend with multiple obstacles along the way that prevent them from getting to where they need to be.
Hitting the wall
The Rogue River was once one of the most productive salmon rivers along the west coast of the United States, but 1,200 barriers block their passage, compromising current populations.
The Rogue River provides crucial spawning habitat for several stocks of the commercially and recreationally prized fish species, such as Chinook salmon.
© WWF-Canon / Kevin Schafer
“Dams are the number one fish killer in the Rogue River Basin,” Barr exclaimed.
“Hundreds of thousands of Chinook and coho salmon and steelhead trout pile up against them as they try to find a way past them all year long.”
The first obstacle salmon come across when starting their yearly migration from the Pacific is the Savage Rapids Dam. Built in 1921, this old, decrepit dam located 170km upstream from the ocean still slows salmon down, and in some cases, prevents them from reaching spawning habitats up river. The 12 meter-high dam is used solely to divert water for irrigation — it provides no storage, flood control, or hydropower.
Removing the dams
But, hopefully this will change during summer of 2007 when a US Federal court decree requiring the Grants Pass Irrigation District to remove the dam goes into effect, ultimately allowing salmon to pass this section of the river without hindrance.
"There is still a lot of work to do to secure the millions of dollars necessary to remove Savage Rapids Dam and the next two dams located immediately upstream," said Bob Hunter from WaterWatch of Oregon, a non-profit river conservation group devoted to restoring and protecting natural river flows in Oregon.
The Savage Rapids dam – built in 1921 some 160km upstream from the Pacific Ocean in the US State of Oregon – slows salmon down, and in some cases, prevents them from reaching spawning habitats up river.
© WWF-Canon / Jamie Pittock
"Fortunately for the Rogue River, the dam owners are working cooperatively to secure the funds to move these great projects along."
The US National Marine Fisheries Service and the Bureau of Reclamation agree that the US$6 million it will cost to remove the Savage Rapids Dam and install irrigation pumps is the most biologically-sound way to restore fish passage at the site.
In addition to Savage Rapids, there is also a commitment to remove the Gold Hill Diversion Dam, the salmon’s second major hurdle on the Rogue River. This diversion dam, located only 24km further upstream, supplies the municipal water source for the city of Gold Hill. WWF is working with the city, local government, state and federal agencies, and WaterWatch of Oregon, to raise the US$2 million necessary to remove this structure. Currently, Gold Hill is installing a new water supply system on the Rogue that will eliminate the need for the diversion.
"As soon as the new water supply intake is in place, the old Gold Hill dam will serve no useful purpose and should be removed," said Craig Harper of the Rogue Valley Council of Governments. "It’s an eyesore, poses safety problems for people, and kills fish.”
Next on the list of dam removals is the inactive Gold Ray Dam, just 5km up from Gold Hill. Although it has a fish ladder that allows salmon to climb up and over this five metre-high structure, it does not meet minimum standards for adequate fish passage. There are no plans currently underway to address fish passage at Gold Ray, but it is clearly the next likely location to address salmon migration restoration along the river.
Climbing the ladder
It’s an early June day and four huge spring-run Chinook salmon are spied resting in the slack water just upstream of the Gold Hill Diversion Dam. A fungus is visible on all four of the 1.5 metre-long fish, with two almost completely covered by the disease.
“These fish have battered their bodies so badly with unsuccessful leaps against the concrete of the Savage Rapids’ poorly designed fish ladder and the Gold Hill Diversion structure that the fungus will likely kill them before spawning begins in September,” said Barr.
“The fish damage themselves and can become exhausted in their search for a way over the dams.”
Further on at Gold Ray Dam another salmon attempts to leap from pool to pool up a steep ladder. Water is spilling over the sides of the ladder with flows far too great to create the specific hydraulic conditions that would allow the migrating fish to swim efficiently through the structure and over the dam. As a result, salmon appear to fail in their leaps as often as they succeed, frequently getting washed down a step in their exhaustion.
“While it is possible to build successful fish ladders at smaller dams, each and every barrier has the potential to damage these salmon and delays them on their race upstream to reach the safety of cool water before the heat of summer stresses them, potentially to their death,” Barr stressed.
“We can see the battered adult salmon migrating up from the Pacific, but far greater numbers of juvenile salmon migrating downstream over the dams to the sea are killed by many of these structures.”
Working up river
Even further upstream in some of the river’s tributaries, WWF has been working with landowners to remove smaller barriers, many less than two-metres high that prevent migrating fish from getting to where they need to spawn. For the past two years, the global conservation organization has provided some of the funding needed to remove eight structures blocking fish passage on Sucker Creek, restoring some 360km of river access for salmon to streams where they spawn.
Restoring the river for salmon will also help populations of other depleted and threatened fish and wildlife species such as river otters. Helping water users find environmentally-friendly alternatives to dams is also an important part of the work. For example, installing pumps to replace dams prevents the diversion of juvenile salmon out of the river system. Replacing leaky canals with pipes can save 50–100 per cent of the diverted water during the dry summer months.
“By the end of 2007, we hope to remove at least 12 of the most important barriers to fish in the Rogue River Basin,” said Barr.
“I’m looking forward to the day when Rogue Basin salmon runs are restored to their former grandeur. A healthy salmon run means a healthy river for both people and wildlife.”
Jamie Pittock is Director of WWF’s Global Freshwater Programme
NOTE: The four species of salmon are key species for the entire Rogue River ecosystem, providing a nutritious food source to a multitude of animals – ranging in size from tiny songbirds to the mighty bears of the region. Salmon carcasses provide much-needed trace minerals, assimilated from the sea, to relatively sterile cold water streams.
A WWF report – Rivers at Risk – identifies the top 21 rivers at risk from dams being planned or under construction, including the Yangtze in China, the La Plata in South America, and the Tigris and Euphrates in the Middle East. The report shows that over 60 per cent of the world’s 227 largest rivers have been fragmented by dams, which has led to the destruction of wetlands, a decline in freshwater species – including river dolphins, fish, and birds – and the forced displacement of tens of millions of people.