Flows in the lower Snake and Columbia rivers
during May were well above average and so was spill and levels of total
dissolved gas in the tailwaters of dams, as well as in dams’ forebays,
according to a second report on court-ordered spill.
The report was compiled by the U.S. Army Corps
of Engineers’ Northwest Division Office and delivered, as required to the U.S.
District Court in Oregon June 15. The Corps will provide one more spring spill
report to cover the period through June 20, when court-ordered spring spill to
TDG limits ended.
Spring spill to aid juvenile salmon and
steelhead passage that began in the Snake River April 3 and on the Columbia
River April 10 was ordered by Judge Michael H. Simon in an April 2017 decision.
The report describes spill operations by the
Corps at four lower Snake River and four lower Columbia River dams during May.
A previous report covered the month of April.
(see CBB, June 8, 2018, “NOAA Fisheries Delivers First Court-Ordered Spring
Spill For Fish Report; Shows Complex Operations,” http://www.cbbulletin.com/440890.aspx).
Additional spring spill up to the maximum
total dissolved gas levels allowed by state water quality rules, called gas
caps, was ordered by the court one year ago. However, its implementation was
delayed a year by the court to allow time for federal agencies to develop a
The Bonneville Power Administration last week
reported the power cost for the additional spring spill to be $10.2 million for
fiscal year 2018. Those costs are largely the value of lost revenue if it was
able to use the additional spill to generate electricity. BPA released its
final costs June 21, 2018.
Total dissolved gas limits are intended to
protect young fish from gas bubble trauma in the dams’ tailraces during spill.
“The month of May was characterized by well
above average flows for the lower Snake and lower Columbia rivers along with
above average air temperatures and widely varying precipitation across the
Columbia Basin,” the June 15 report says.
It goes on to say that May precipitation was
96 percent of average on the Snake River above Ice Harbor and 78 percent of
average on the Columbia River above The Dalles Dam.
However, runoff in the two rivers was far
above normal, with the Northwest River Forecast Center runoff summary for May
showing higher than average runoff. The Snake River at Lower Granite Dam was
149 percent of the 30-year average (1981-2010) with a volume of 10.3 million
acre feet, while May runoff for the Columbia River at The Dalles Dam was 176
percent of the 30-year average, with a volume of 44.6 MAF.
Simon’s court order calls for the Corps to
strive for spill at gas cap levels of 120 percent TDG at all eight dam
tailwaters and at 115 percent in the forebays of each of the dams, which are
limits set by the states of Oregon and Washington. However, during May gas caps
were exceeded much of the time, particularly in dams’ forebays, when high flows
caused spill higher than spill targets developed by the Corps.
See Snake River spill and TDG results at http://pweb.crohms.org/ftppub/water_quality/12hr/snake_river.html
, and Columbia River results at http://pweb.crohms.org/ftppub/water_quality/12hr/columbia.html.
The Corps said the spill cap operation this
year is a more complex operation than in previous years.
“In its implementation of the 2018 Spring FOP
(fish operations plan) in May, the Corps evaluated conditions every day to
establish spill caps at a level that was estimated to meet, but not exceed, the
gas cap in the tailrace and the next downstream forebay,” the Corps’ second
report says. “This evaluation considered: environmental conditions (e.g., river
flow, wind, water temperature, barometric pressure, incoming TDG from upstream,
and water travel time) and project operations (e.g., spill level, spill
pattern, tailwater elevation, proportion of flow through the turbines, and
project configuration). For the month of May 2018, conditions constraining the
spill cap at Bonneville and The Dalles dams did not occur.”
A disagreement on how “spill to the gas cap”
should be interpreted occurred at the June 13 meeting of the interagency
Technical Management Team. At that meeting, Julie Ammann of the Corps said that
“We need to meet, not exceed, state water quality standards.” However,
fisheries managers thought the Corps should be more aggressive by shooting for
an average cap of 120 percent in the tailwater and 115 percent in the
(See CBB, June 15, 2018, “Fish/River Managers
Have Differing Interpretations On What ‘Spill To The Gas Cap’ Looks Like,” http://www.cbbulletin.com/440945.aspx).
At Lower Granite Dam spill exceeded the Corps’
target spill (about 36,000 to 38,000 cubic feet per second) on all but about
seven days in May, with flows at one point exceeding 180 kcfs and actual spill
hitting 80 kcfs. Tailwater TDG percentage at Granite rose to the mid- to
low-120s at the end of the month.
Downstream, the Little Goose forebay saw TDG
over 115 percent about half the month. Little Goose Dam tailwater TDG was over
120 percent 18 days.
Lower Monumental Dam forebay exceeded the 115
percent gas cap all but one day in May, reaching as high as 126 percent. The
dam’s tailwater exceeded the gas cap 20 days in May.
The Ice Harbor Dam forebay exceeded the gas
cap of 115 percent every day in the month. Flows at Ice Harbor approached 200
kcfs May 27, with spill at 140 kcfs (target spill was 80 kcfs). Ice Harbor
tailwater exceeded the gas cap 22 of 31 days.
Spill on the Columbia River followed a similar
pattern. McNary Dam flow hovered around the 500 kcfs mark for much of the
middle and late parts of May. Spill hit 380 kcfs May 17, while the spill target
was 150 kcfs. The McNary forebay exceeded the gas cap on all but three days in
May. Tailwater TDG at McNary exceeded the gas cap all but five days in May.
John Day, The Dalles and Bonneville dams
followed a similar pattern of flow and spill, but with fewer spikes in actual
spill (the spill targets at John Day and The Dalles was about 95 kcfs, and
about 125 kcfs at Bonneville).
The John Day forebay TDG exceeded the gas cap
on all but four days in May (the first four days). The John Day tailwater
exceeded the gas cap on all but the first four days of the month, reaching 134
percent TDG on two of the days.
The Dalles forebay exceeded the gas cap on all
but the first four days of May and the tailwater exceeded the gas cap on all
but four days, but the days were dispersed throughout the month.
The Bonneville Dam exceeded gas cap limits in
the forebay and tailwater every day of the month (the sensor in the tailwater
was out of commission the last half of the month).
There were some breaks in the spill protocol
at Lower Granite, Little Goose and The Dalles dams. On May 2 at Lower Granite
all generating units were out during the day while transmission repairs were
underway. The Corps spilled as much water as possible during the outage, while
controlling TDG as best as it could, and it stored water behind the dam in
order to control the amount of water spilled.
Passage delays of adult chinook salmon caused
TMT to ask for controlled spill of 30 kcfs during the day at Little Goose Dam
May 30 to June 2. To do that, the Corps stored water and released it overnight.
On the afternoon of May 31 the Corps shut down
all spill at The Dalles Dam for 25 minutes for an emergency rescue of a boat
caught in the spillway.
The request for injunctive relief for more
spill was enjoined with an earlier case argued in District Court. The initial
case, heard by Simon, resulted in a May 2016 remand of the federal Columbia
River power system biological opinion for salmon and steelhead listed under the
Endangered Species Act.
The spill plea was initiated in January 2017
by plaintiffs in the original case, the National Wildlife Federation and the
State of Oregon, among others, asking the court to begin ordering spill to
maximum total dissolved gas levels as set by the states beginning April 3, 2017
and to continue for each year of the BiOp remand.
Simon agreed that more spring spill would
benefit ESA-listed fish but delayed the action until 2018 while federal
agencies completed a spill plan for the dams. The plan is for additional spill
only during the spring of 2018 to TDG caps, as well as for earlier PIT-tag
monitoring of juvenile salmon.
NOAA Fisheries, Northwest RiverPartners, the
Kootenai Tribe of Idaho, the states of Idaho and Montana, and the Inland Ports
and Navigation Group appealed Simon’s spill injunction in early June 2017 to
the Ninth Circuit Court of Appeals. However a three-judge panel of the appeals
court ruled April 2 in favor of Simon’s spill ruling.
Bonneville released the Administrator’s
Decision, Implementation of the FY 2018 Spill Surcharge (FY 2018 Spill
Surcharge Decision), memorializing the final decision to implement the Fiscal
Year (FY) 2018 Spill Surcharge in an amount of $10.2 million for FY 2018,
according to BPA. The regional utility will apply a rate of 0.71 mills per
kilowatt-hour for June–September 2018; and an Annual rate of 0.23 mills per
kilowatt-hour. The FY 2018 Spill Surcharge Decision also addresses comments
received during the public comment period. See https://www.bpa.gov/Finance/RateCases/surcharge18/Pages/default.aspx.
--CBB, May 18, 2018, “Court-Ordered Spring
Spill Now Moot As High Columbia/Snake Flows Forcing Involuntary Spill At Dams,”
--CBB, April 13, 2018, “Court Ordered Spring
Spill For Fish Begins On Four Lower Columbia River Dams,” http://www.cbbulletin.com/440516.aspx
-- CBB, April 6, 2018, “New Court-Ordered
Spill Regime Based On Dissolved Gas Caps Begins This Week,” http://www.cbbulletin.com/440479.aspx