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Fish/River Managers Have Differing Interpretations
On What 'Spill to the Gas Cap' Looks Like

by Staff
Columbia Basin Bulletin, June 15, 2018

June 6 TDG in the Lower Granite Dam tailrace has averaged about 116%, with a low of 115% and a high of 118%,
forebay at Little Goose Dam was as low as 110% (upper gas cap for forebays is 115%, upper gas cap for forebays is 115%)

(Blaine Harden) Little Goose and other federal dams have been ordered to spill water to keep migrating salmon in the Snake River, avoiding potentially deadly turbines. As river flows decline and court-ordered spill to gas caps comes to an end at eight Snake and Columbia River dams, fisheries managers at the interagency Technical Management Team this week argued over how "spill to the gas cap" should be defined.

Snow-melt throughout May and early June forced spill at the dams to uncontrolled or involuntary levels, most of the time much higher than was called for by the U.S. District Court in a decision in April 2017. With involuntary spill, total dissolved gas levels in each of the dam's tailwaters and in the downstream dam's forebay exceeded water quality limits set by Oregon and Washington.

Now flows and spill have dropped, which has allowed the U.S. Army Corps of Engineers to resume spilling to court-ordered state mandated total dissolved gas levels, known as gas caps -- 120 percent TDG in tailraces and 115 percent TDG in the downstream dam's forebay.

A three-judge panel of the Ninth Circuit Court of Appeals ruled April 2, 2018 in favor of an April 2017 U.S. District Court injunction allowing more spring spill at four lower Snake and four lower Columbia river dams. With the decision, spill to the gas cap began April 3 at lower Snake River dams and at lower Columbia River dams April 10. The additional spill through June 15 is designed to aid migrating juvenile salmon and steelhead.

While both fisheries and river managers at this week's TMT meeting, June 13, agreed that the Corps should continue gas-cap spill right up to today's deadline for the operation, June 15, when court-ordered gas cap spill is to end, differences arose among some fisheries managers and the Corps as to how aggressive the dam operating agency should be when pushing up against state dissolved gas limits.

Higher than normal flows, spill and TDG that plagued the spill cap operations in May have returned to manageable levels, according to a presentation at TMT by Dan Turner of the Corps' River Control Center.

He showed recent lower Snake River spill targets that did not always result in reaching gas cap limits. For example, since June 6 TDG in the Lower Granite Dam tailrace has averaged about 116 percent, with a low of 115 percent and a high of 118 percent (upper gas cap for tailwater is 120 percent), while the downstream forebay at Little Goose Dam was as low as 110 percent (upper gas cap for forebays is 115 percent).

At McNary Dam tailrace TDG has been consistent since June 8 at 118 percent, while forebay TDG at John Day Dam dropped to as low as 109 percent June 12 and 13.

"There has been a lot of frustration about spill not reaching the gas cap over the last week," Paul Wagner of NOAA Fisheries said at the TMT meeting.

"Last Tuesday we were in a declining hydrograph transition from involuntary to voluntary spill," Russ Kiefer of Idaho Department of Fish and Game told TMT. "There is a pattern here where the high TDG of involuntary spill has resulted in a delayed response by the Corps to bring spill caps up to meet the current conditions."

"The Corps team is working hard to do the best at managing a difficult situation," said Julie Ammann of the Corps. "Overall we're making an effort to meet spill caps at all projects. We need to meet, not exceed, state water quality standards."

"It seems more like an effort to not meet the court order," said Erick VanDyke of the Oregon Department of Fish and Wildlife. "I hope to get back to maximizing spill and I hope the Corps will do that."

Dave Statler of the Nez Perce Tribe said the Corps should be aggressive as possible with spill caps. "I hope we don't get to a point where we're too cautious and not exceeding the spill caps on any day.

"It's easy to say 'meet spill caps,' but everyone has a different interpretation of what that means," Statler said.

"We've never strived to go over spill caps," Ammann said. "We have taken what we've learned this year and are trying to apply it to our operations."

(See CBB, May 4, 2018, Maintaining Court-Ordered Spill At Columbia/Snake Dams Without Exceeding Gas Caps Proves Challenging)

According to Jim Litchfield, who represents Montana at TMT, that state considers the gas cap a maximum upper limit. "It's not a target, it's a limit," he said.

"You can exceed 115 percent in forebays, but the average needs to meet the target," Charles Morell of the Washington Department of Fish and Wildlife said of how he thought gas cap spill should be defined.

We interpret it to meet, but not to exceed, Turner of the Corps concluded.

Related Sites:
NOAA Fisheries Delivers First Court-Ordered Spring Spill For Fish Report; Shows Complex Operations by Staff, Columbia Basin Bulletin 6/8/18
Court-Ordered Spring Spill Now Moot As High Columbia/Snake Flows Forcing Involuntary Spill At Dams by Staff, Columbia Basin Bulletin 5/18/18
Court Ordered Spring Spill For Fish Begins On Four Lower Columbia River Dams by Staff, Columbia Basin Bulletin 4/13/18
Appeals Court Rules In Favor Of More Spill For Juvenile Salmon, Steelhead At Columbia/Snake Dams by Staff, Columbia Basin Bulletin 4/6/18
New Court-Ordered Spill Regime Based On Dissolved Gas Caps Begins This Week by Staff, Columbia Basin Bulletin 4/6/18
Ninth Circuit Hears Arguments On More Spill For Juvenile Salmon/Steelhead At Columbia/Snake Dams by Staff, Columbia Basin Bulletin 3/3/18
Briefs Filed In Appeals Court To Expedite Challenge To Increased Spill For Juvenile Salmon, Steelhead by Staff, Columbia Basin Bulletin 12/8/17

Fish/River Managers Have Differing Interpretations on What 'Spill to the Gas Cap' Looks Like
Columbia Basin Bulletin, June 15, 2018

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