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NW Fishletter #257, February 9, 2009

[3] States Reach Split Decision Over TDG Monitoring

Last month, Washington and Oregon came up on opposite sides of another fish-management issue. It's a fairly common occurrence as litigation over the hydro BiOp heads for a showdown in early March, when the two states square off in oral arguments over the latest fish plan.

After more than a year of meetings, a group of water quality managers from Washington announced Jan. 12 that it would not change its 115-percent total dissolved gas [TDG] water quality criterion for dam forebays in the Columbia and Snake rivers--the level the BiOp calls for to manage spill during the fish passage season.

The Corps of Engineers is applying for a new 5-year waiver of Clean Water Act standards to allow the BiOp-level spill at dams. But added spill usually boosts total dissolved gas levels above the legal limit of 110 percent. Until now, the waiver has capped forebay limits at 115 percent and tailrace limits at 120 percent.

All parties support the waiver. But salmon advocates and some conservation and fishing groups are lined up behind technical reviews supplied by the Fish Passage Center that say removing the forebay monitors would allow more spill and provide a significant boost to juvenile fish survival. And for years, state fish agencies and tribes have argued that because of their location, some of the monitors aren't producing reliable TDG readings.

The two states have different ways to deal with changes to the current TDG limits--Washington would implement a complicated rule change, and Oregon would grant waivers.

Using analyses from the Fish Passage Center, Oregon fish managers had already called for removing forebay gas monitors at mainstem dams in hopes of wringing a little more spill for fish at the dams. It was an approach other plaintiffs endorsed in the current litigation over the 2008 BiOp.

But in the final analysis, most participants said any potential fish benefits were lost in the "decimal dust" of the methodologies.

Washington's Department of Ecology decided changing the standard wasn't worth it. According to a bi-state report issued last week, "Ecology determined that there would be a potential for a small benefit to salmon related to fish spill if the 115-percent forebay criterion was eliminated, but there would also be the potential for a small increase in harm from increased gas bubble trauma."

The state agency said "the weight of all evidence from available scientific studies clearly points to detrimental effects on aquatic life near the surface when TDG approaches 120 percent.

The detrimental effects ranged from behavior changes to high levels of mortality after a few days. There were fewer effects on aquatic life at 115 percent TDG. Ecology strongly encourages implementing actions that increase salmonid survival without further increasing total dissolved gas."

Ecology outlined the administrative procedures that would be required to implement a change, which included a cost-benefit analysis, a small business economic impact statement and a possible environmental impact statement.

The bottom line, for Ecology--"Based on the information in this document, Ecology does not believe the overall benefits of additional spill versus additional risk of gas bubble trauma are clear and sufficient for a rule revision."

Oregon water quality managers concluded differently.

They saw no need to maintain the forebay monitors in 2009 because they say the requirement "will not cause excessive harm to the beneficial use, aquatic species, in the Columbia River during fish passage spill season."

The review by the two states found that spill at the dams would increase by 1 to 2 percent without the forebay monitors and could boost juvenile chinook survival by less than 1 percent, but might have small negative effects on Snake River steelhead.

The report noted that ODEQ and Ecology used four different methods provided by fish management agencies to estimate fish survival--with a high level of uncertainty and controversy associated with each one.

The process to sort out this issue began in November 2007, and generated a fair amount of heated discussion at meetings that culminated last summer, when both NOAA Fisheries and the Corps of Engineers criticized a Fish Passage Center analysis of a spill option that wasn't even under consideration.

The FPC modeled an additional hydro scenario to the two in question--the current spill program with 115-percent forebay/120-percent tailrace limits, and spill with only a 120-percent tailrace limit. Depending on the dam, the change could be significant between the two operations, especially at Lower Monumental Dam on the Snake, and Bonneville in the lower Columbia.

However, the FPC's extra analysis looked at what could be gained in fish survival from an operation that spilled to 120-percent of TDG limits, but was not constrained by what the FPC called "planned operations," a situation never clearly defined in its submissions.

FPC said such a scenario could boost spring chinook survival to more than 90 percent from 65 percent under the scenario that was limited by planned operations.

The two federal agencies said the FPC analysis hugely overstated the amount of spill that was available to help juvenile fish pass the dams.

BPA power analyst Roger Schiewe said the FPC's analysis had stripped out what is called "excess generation spill," spill that might occur from lack of marketing or be needed when turbines go out. In other words, it didn't reflect the reality of real-time hydro operations.

In comments submitted to the water quality agencies, BPA said its own hydro model "properly reflects the reality of the hydro system. At times, the hydro system can produce more energy than can be safely transmitted to serve load in the region or distant power markets. In addition, there are times when the hydro system can generate power in excess of demand. It would be irresponsible for these realities to be ignored and would distort the results."

Back in March 2008, the Corps of Engineers said the FPC methodology left out many of the factors included in its own hydro model and called the FPC result "unreliable." The Corps' maximum additional spill was about half of the FPC's 58 million acre-feet that could occur if all limitations but the 120-percent tailrace limit for TDG were removed, a minimum generation condition.

In high water years, the Corps figured that another 6 MAF could be spilled if the 115-percent TDG standard were removed. In low water years, that went down to 5.2 MAF.

More important, they said the kind of water year (low versus high) would account for more than an 11-MAF difference in the additional spill volume that could occur.

The Corps and NOAA never modeled the FPC's added scenario because they felt it didn't reflect a reasonable possibility. But for operations in a high-flow year, they estimated only a 1.9-percent boost in spring chinook survival if dams were managed without the 115-percent forebay limit, compared to the FPC's estimate of a 13-percent increase in survival.

NOAA Fisheries' COMPASS model estimated the 120-percent-only scenario would produce only a 0.922-percent increase for Snake spring chinook and a 1.1-percent decline in survival of Snake steelhead, because the slight increase in spill meant fewer of them would be routed to barges. -B. R.

The following links were mentioned in this story:

Ecology and ODEQ Evaluation of the 115% Total Dissolved Gas Forebay Requirement, January, 2009

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