Avista Corp. could face a $60 million tab to modify its Cabinet Gorge dam on Idahos Clark Fork River to protect fish there.


The money would be spent over a long periodthrough 2020and part of the work ultimately might prove to be unnecessary, says Bob Anderson, the Spokane-based utilitys director of environmental affairs. Avista already has submitted a plan, however, to spend $37 million in the first part of the project.


Avista could face the same issue on at least one of its Spokane River dams, although the company is still in the process of investigating whether thats the case, Anderson says. In any event, those dams are much smaller than Cabinet Gorge and would be less expensive to modify, he says.


The company pledged to address the problem of dissolved gases in water downstream from the Cabinet Gorge dam when the Federal Energy Regulatory Commission (FERC) relicensed the hydropower facility several years ago. The dam is located near the Montana border, about seven miles upstream from where the Clark Fork empties into Lake Pend Oreille. Avistas other dam on that river, Noxon Rapids, in Montana, doesnt create high levels of dissolved gases because it was constructed differently, Anderson says.


At Cabinet Gorge, the dam produces dissolved gases downstream in the Clark Fork only during spring runoff, when huge volumes of water plunge over the dams spillway, he says.


The gases are dissolved when water comes into contact with the air as it goes over the spillway, then traps nitrogen and oxygen from the air in the deep spilling basin below. The gases can cause a potentially fatal bubble disease in the blood vessels of fish, which is akin to a diver experiencing the bends, Anderson says. All fish can be impacted by the disease, including the bull trout, a threatened species thats present in the Clark Fork.


Studies conducted by Avista havent shown any significant impact on the fishery resource on the Clark Fork due to the dissolved gases, he says, but the problem is you cant say for sure whether thats the case. Testing the fish during high-water episodes is difficult, Anderson says.


Avistas proposal for reducing the level of dissolved gases involves modifying two now-closed tunnels at the Cabinet Gorge dam that were created to divert the river during the dams construction in the early 1950s.


The modifications would allow the tunnels to be opened so that the utility could divert water through them during high-water periods, then close them again when the water level falls. Reducing the volume of water that goes over the dams spillway is expected to lower the level of dissolved gases in the water below the dam, Anderson says.


Work on the first tunnel in the plan Avista already has submitted would cost about $37 million, and would take place between 2004 and 2009, Anderson says.


Its conceivable that diverting water through the first tunnel would reduce the level of dissolved gases to an acceptable measure, so modifications wouldnt be needed on the second tunnel, he says.


If work on the second tunnel is deemed to be necessary, however, modifications to it are expected to cost $23 million. The first project would be more expensive than the second because it would include some preliminary work on the second tunnel, Anderson says.


The company has submitted its proposed plan for modifying Cabinet Gorge to FERC, the Idaho Department of Environmental Quality, and the U.S. Fish and Wildlife Service for those agencies scrutiny. It expects an answer from the agencies this year, Anderson says.


Avista would ask regulators for permission to recoup from ratepayers its expenditures at Cabinet Gorge, he says. The project wouldnt be likely to increase utility rates much, however, because its cost would be amortized over many years, he says.


Furthermore, Jim Bellessa, a securities analyst at D.A. Davidson & Co. in Great Falls, Mont., says it could take years for the expense to show up in ratepayers Avista bills.


It wouldnt show up until they actually made the expenditure then made a rate application, he says. Theres a regulatory lag.


This year, Avista expects to spend $90 million to $110 million on capital projects for its utilities division.


Long Lake next?


Meanwhile, Avista is in the process of asking FERC to relicense five of its six Spokane River hydroelectric plants, and the issue of dissolved gases could come up in that process as well, Anderson says.


We have noticed some high dissolved gas levels below Long Lake, and were working on that, he says of the companys Long Lake dam, northwest of Spokane.


Even if Avista has to spend money to fix that facility, however, it wouldnt cost near as much as the Cabinet Gorge project, he says.


Cabinet Gorge is by far the highest cost because its such a big facility, he says. The Spokane River dams are much, much smaller.


Avista expects to complete its relicensing application for those dams and submit it to FERC by July 2005. Those dams licenses expire in 2007.


Mitigation fees


Until Avista can lower the level of dissolved gases in the water below Cabinet Gorgeor prove that they dont have a negative biological impact therethe company agreed as part of its relicensing agreement to pay $500,000 a year in mitigation fees to the state of Idaho.


Also under its relicensing agreement with FERC, Avista spends another about $4.7 million annually to address issues related to fisheries, water quality, wildlife, recreation, and land use on the Clark Fork River.