Access all areas11 May 2004
Debra Flickinger reports on PGE’s efforts to improve fish passage in the relicensing application for its T.W. Sullivan plant
PORTLAND GENERAL ELECTRIC’S (PGE) longest-running generation facility, one of the three oldest hydroelectric plants in the US, is headed for another 30 years of operation. On 2 February 2004, Portland, Oregon-based PGE submitted an agreement to the Federal Energy Regulatory Commission (FERC), that will be a key step in renewing its license for the 16MW T.W. Sullivan plant.
Under the agreement, signed by a variety of governmental, environmental and tribal organisations, the Willamette Falls power house will operate with enhanced production capacity and environmental protections.
It provides for several improvements to assist the downstream passage of juvenile fish. In addition, PGE will assume maintenance and any necessary improvements to the facility’s fish ladder to help adult salmon and steelhead move upstream. Improvements to the downstream facilities include moving fish through a tunnel currently used to take water around the plant. A gated opening, or ‘flow structure’ will also be created at the top of the falls to better direct fish downstream. The goal is to achieve a safe passage rate of 98% or better.
The Willamette river is Oregon’s longest and runs entirely within the state. More than two million people live in the Willamette river basin, the fastest growing portion of the state. Located in northwestern Oregon between the Cascade Mountains and the Coast Range, the basin comprises 29,785km2 and is bordered by foothills and mountains up to 3098m high to the south, east, and west. Today, the region continues to serve as one of the only sites in the US where people can fish for the prized Pacific lamprey.
In 1883, the dam at Willamette Falls was constructed to exploit the hydro power potential of the site. The 899.2m-long dam uses the hydraulic head of the falls, a natural horseshoe-shaped cascade approximately 12.2m in height. The dam runs along the top of the falls between two power houses, varying in height from 1.8–6.1m. The dam maintains a consistent water level (but does not provide water storage) to which the hydroelectric projects, several mills and the US Army Corps of Engineers navigation locks are built.
With generators originally used in a Portland sawmill, the Willamette Falls Electric Company made history on 3 June 1889 by originating the first long distance transmission of electricity in the US. Electricity travelled 22.5km from ‘Station A’ (closed in 1897) in Oregon City to power street lights in Portland. ‘Station B’ opened on the West Linn side of the river in 1895. Today, it is the site of the T. W. Sullivan facility.
Just as it has for more than a century, the Willamette river continues to play a vital role in the economy of Oregon. It is an important water source for agriculture and municipal uses as well as for recreational and outdoor activities, including fishing and boating. Moreover, the river and surrounding tributaries are home to a wide variety of fish including spring chinook, winter steelhead, summer steelhead, fall chinook, coho salmon, steelhead and cutthroat trout, as well as the Columbia basin’s largest population of Pacific lamprey.
In this part of the US, salmon are the most important cultural, economic and recreational species of fish. According to the Oregon Department of Fish and Wildlife, over the past decade alone an average of approximately 200,000 adult salmonids return annually from the Pacific Ocean to swim over the Willamette Falls and spawn in the river’s freshwater. Then, every year, approximately three million juvenile salmonid move downstream to rear in the productive waters of the north Pacific Ocean.
‘With its location near the confluence with the Columbia river, almost all salmon in the Willamette basin must go over or around the falls,’ explains John Esler, a PGE licensing project manager. ‘We’ve got juvenile salmon that go downstream and adult salmon that come back upstream to spawn. The fish ladders installed at Willamette Falls have actually increased migrating salmon’s ability to pass over the falls. Before the construction of fish ladders, summer steelhead and coho salmon were rarely found upstream because they couldn’t negotiate the falls during the traditional lower water periods in the summer and fall.’
Esler praises the original engineers’ design. ‘They set the 13 generating units parallel to the river’s flow rather than perpendicular, so migrating fish would be swept with that flow and generally avoid going into the first 12 turbines,’ he says. ‘Unit 13, which is the last turbine in line, is the only unit that has a fish screen and transport system to handle the juvenile salmonids. In that unit’s transport system we can evaluate the condition, size, and abundance of fish before we release them safely below the falls.
‘Overall, 85% of the fish that enter the project are being collected with the fish screen. Of the remaining 15% that go through the other 12 turbines, about 75% of those fish survive. Certainly this translates to a decent survival efficiency, but as a result of relicensing, conditions for fish will get even better,’ says Esler.
In 1998, PGE embarked on an alternative FERC licensing process that identified tough issues at the start and then employed collaboration among 12 government agencies, environmental organisations and tribal interests to prepare a mutually agreeable license application.
The objective was to develop a consensus, says David Heintzman, a PGE project manager. ‘In our estimation, it was the best way to gain and incorporate the input of everyone who had a vested interest in the project and avoid a potential adversarial outcome.’
‘To resolve a particular quandary, we approached the collaborating parties with a proposal,’ explains Esler. ‘If PGE would bear the risks associated with meeting the same survival standards for migrating fish as if the generating units were screened, could we then implement a set of conservation measures as alternatives to screening all the units?
‘As you can imagine, such a proposal took everyone by surprise. They questioned whether PGE would be willing to accept the consequences if we did not achieve the standard. But, we had done our homework, and the models we ran said we should be successful,’ he comments. ‘Moreover, we agreed that if the initial tactics fail to meet the standard, we will go back to the drawing board and continue to develop and implement new measures until we reach the 98% standard.’
The agencies agreed. If PGE’s proposal works, the results will be as good for fish as if screens were installed, yet at a significantly lower cost.
To achieve the 98% standard, PGE proposes to install ‘slots’, or pneumatically-operated gates, into the concrete dam, thus directing a significant portion of the water into select locations that will result in safer downstream passage for the migrating fish. PGE also plans to create a siphon bypass near turbine unit 13 that will allow more water into the forebay, causing it to sweep smoother and faster past the turbine entrances, through the ‘siphon spillway’ and into the tailrace below the power house.
Esler notes: ‘The only downside of this tactic is that it will reduce our ability to get our hands on as many fish to evaluate because fewer fish will move into the evaluator at unit 13. Instead, fish will be swept down the siphon bypass and safely deposited in the tailrace. However, the upside has made everyone happy, because these tactics will help us achieve 98% passage rates.’
Understanding Pacific Lamprey
With new conditions agreed to for salmon, one more species needed to be considered: Pacific lamprey. Native Americans harvested Pacific lamprey at Willamette Falls for centuries before European settlement of the area.
Today, Pacific lamprey are known to ascend Willamette Falls and pass over the dam, occasionally using the existing fish ladder. Like most salmon species, they spawn in freshwater and then die, while their offspring migrate downstream to saltwater. In saltwater, they become parasitic and feed by rasping a hole in passing fish to gain vital nutrients. On their return trip, disconnected from their hosts, they swim upriver, migrating over the face of the Willamette Falls. Swimming when possible, they also use their ‘sucker-like’ mouths to attach themselves to the rock walls as they climb the falls.
While the Willamette Basin is considered a significant production area for Pacific lamprey in the Columbia river basin, the state of the lamprey population is not clear. Although, they are important to the ecology of the basin as well as to the Native American culture, the Lamprey has not been given the same attention as Pacific Northwest salmonids. Therefore, with strong encouragement by the Tribes, as part of the agreement PGE will fund a major research programme to assess how effective lamprey passage currently is at the falls, identify specific passage obstacles and determine how to address those obstacles.
The licence that will allow the Sullivan hydroelectric plant at Willamette Falls to operate for another 30 years reflects a settlement that is considered a win for both the economy and the environment. The agreement will make improvements that promise to put safe fish passage at the falls at the highest levels in history, while at the same time delivering increased production capacity.
For further information regarding the Willamette Falls project, please call Mark Fryburg of PGE on +1 503 464 8444 or email: [email protected]TablesTable 1 Table 2