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Columbia River Water Supply Improves

by Bill Rudolph
NW Fishletter, August 23(?), 2001

Flows, Spill Boosted

Citing a January-to-July water supply forecast that BPA now says proved to be a bit low, the agency has boosted flows in the hydro system and bumped up spill for fish as well, along with getting back in the power market.

The agency announced the boost at the Technical Management Team meeting in Portland Aug. 8, but the word was out a little before that. "That's why I didn't go to the meeting," said consultant Jim Litchfield, who represents the state of Montana. "It was a done deal."

BPA's Therese Lamb announced that flows would go up to the 90-100 kcfs range at Bonneville Dam--up from around 80 kcfs--and the 45 kcfs that was spilled for fish passage for five hours every night was going up to 50 kcfs that would be spilled around the clock. She said the 24-hour spill at The Dalles was increasing from 30 percent to 40 percent. This optimistic turn of events had to do with the actual amount of water measured past The Dalles from January through July--58.4 MAF--about 3.5 MAF above the last forecast issued in early July.

The spill program could still end early if the agency's financial situation changes or the outlook for system storage worsens, said Lamb. Later, she told NW Fishletter that it's the financial situation that's been so hard to pin down, factoring in the uncertain impacts of the West Coast power price cap, new loads and effects of the pending rate case.

For now, everything's rosey, said BPA spokesman Ed Mosey. The hydro system has built up more than 33,000 MW-months of storage, already surpassing the 28,000 MW-months of storage the agency was targeting to reach by Oct. 1. Because the forecast came in on the low side, Mosey said power purchases made to build storage while the hydro system has been operating at "minimums" have paid off this summer more than expected.

He noted that the NWPPC's reliability study shows little benefit from storing more the 28,000 MW-months because of the limitations of regional generating capacity. With that much storage, the study figured the loss of load probability at 12 percent.

Others have pointed out that the study may be a bit dated already, since diesel generation that had been added to regional capacity has since been sidelined by low prices. Also, the NWPPC study didn't account for transmission constraints in the Northwest, especially between Montana and Eastern Washington. A BPA document handed out at the July 18 TMT meeting brought up these issues and said internal studies indicated that more storage may improve loss of load probability more than the Council's analysis suggested. But that same document had expressed concern over reaching the 28,000 MW-month target, which has moderated considerably since then.

Lamb explained that the forecast model had used three scenarios to look at probable runoff, with low, medium and high stream flows. "It turned out that stream flows were medium to high for the period," she said. And she also noted that the standard deviation for the model was 3.5 MAF--which was exactly how much it low-balled the Jan.-July water supply.

So, the agency finds itself with a little more flexibility, she said. "We don't need to operate at minimums," she added, noting that the system is being drafted from both Coulee and Canadian reservoirs to boost flows, increase spill and allow for some power sales to cushion the uncertainties of the financial picture.

By the end of August, the system will have spilled about 350 to 400 MW-months' worth of water for summer spill, said Mosey, with a value of about $7 million, in addition to the $5 million worth of spring spill. As of last week, about 400-450 MW was being spilled daily.

The biological benefits for the increased spill weren't quantified, but neither were they penciled out when the limited summer spill effort commenced on July 24. Discussion at the time found fish and hydro managers at odds, as usual, but it was generally accepted that spill at The Dalles could boost survival by about 3 percent, while the Bonneville spill might result in no net survival gain. Later, a NMFS analysis estimated that the benefit of spill at The Dalles was a 4 percent survival improvement, and 6 percent at Bonneville.

Fish managers were relatively happy. CRITFC's Bob Heinith said any increase in flows and spill would be helpful. But BPA biologist Bill Maslen said about 80 percent of the fall chinook run had already passed John Day Dam.

Doug Arndt, chief of the Corps of Engineers' fish management division, said he had fielded a few calls critical of the expanded flow program, including one from Congressman Butch Otter's (R-ID) head staffer Todd Ungerecht.

Arndt said the Corps is prepared to do what it can to meet BiOp spills, "as long as it doesn't threaten short- or long-term reliability of the power system." He said BPA has assured them that "worst-case hydraulics" won't mean that flows could dip below 70 kcfs at Bonneville--the minimum required for powerhouse operation. But Arndt said it's possible that more water could come from Idaho's Dworshak reservoir, even though it's expected to be drafted to its lowest level of the summer, elevation 1520 feet, by the end of August. Using more could risk not reaching BiOp-mandated levels by next April, Arndt explained.

"Come September, if we have to dig into Dworshak...just watch the finger-pointing." He did note that the new BiOp calls for an experimental drawdown of Dworshak to 1500 feet to study effects on migrating adults in late summer, but he cautioned that this might not be the most prudent year to try it out.

BPA's Lamb sounded more positive about the possibility of using additional Dworshak water, but was still pretty sure that the system would be able to add five more feet to Coulee next month and maintain flows without it.

Arndt also pointed out that if the region experiences a cold snap this winter, the first place it goes for more power is Dworshak--which could make it even tougher to reach BiOp levels next spring. And don't forget, Arndt, added, chum issues will be coming up for discussion pretty soon. He said without a rainy fall, it may be hard to deliver any extra water to aid ESA-listed chum spawning this year if they settle in the same shallow spots below Bonneville Dam as they did last fall, when an extra 10 kcfs was added to flows most of the winter and early spring to keep redds covered until fry emerged.

Bill Rudolph
Columbia River Water Supply Improves
NW Fishletter, August 23(?), 2001

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