annual study that looks at salmonid survival
through Snake and Columbia river dams for the first time evaluated juvenile fish
survival in the Snake River with and without the presence of the four lower
dams on the river, as well as the impact on survival if spill is increased, as
it may beginning next year.
Fish Passage Center released a draft of its annual Bonneville Power
Administration-funded Comparative Survival Study in late August and is asking
for comment from fisheries managers and the public by October 15. The final CSS
is scheduled for completion by the end of December.
study weighs in on two court-ordered issues: a requirement to consider an
option for recovering Snake River salmon and steelhead by breaching the four
lower Snake River dams and the value of more spill.
study says that its analysis provides insight into the potential for dam
breaching and whether it can play a role in recovering the Snake River
spring/summer chinook that are listed under the federal Endangered Species Act.
results presented demonstrate the relative sensitivity of survival and
long-term return abundance to changes in hydrosystem operations,” the draft CSS
says. “Relying on the empirical estimates of life cycle model parameters, and
particularly the finding that powerhouse passage is a significant determinant
of in-river survival and early ocean survival, we demonstrated that dam
breaching and increased spill can benefit population recovery in relative
proportion to the productivities and capacities of the populations.”
analysis predicts that average return abundances and smolt-to-adult returns
increase at higher levels of spill and when dams are breached. That is “owing
to the empirical finding that survival is higher when powerhouse passage and
water transit times are lower.”
draft study also says that the results are preliminary because the future
conditions simulated by the CSS model are speculative and have a strong
influence on predicted survival, but also because the passage assumptions after
breaching the dams have not been empirically tested.
predicted outcomes represent approximations of the relative magnitude of
increased survival and return abundance that are predicted relative to expected
passage and water transit time values under flow, spill, and breach conditions,”
the draft study says.
a river that still has the four dams in place, the report predicts a 2 to 2.5
fold increase in return abundance when spill is increased beyond levels called
for in the latest biological opinion for the federal Columbia/Snake river power
system, and up to levels that would result in total dissolved gas levels of 125
the lower Snake River dams – Ice Harbor, Lower Monumental, Little Goose and
Lower Granite dams – are breached and the remaining four lower Columbia dams –
McNary, John Day, The Dalles and Bonneville dams – operate at BiOp spill
levels, then the CSS analysis predicts a 2 to 3 fold increase in abundance
above that predicted at BiOp spill levels in a river where the four dams
remain. If the TDG limit at the Columbia River dams is increased to 125
percent, then the analysis predicts a 4-fold increase in abundance without the
Snake River dams.
analysis predicts that higher SARs and long-term abundances can be achieved by
reducing powerhouse passage and water transit time, both of which are reduced
by increasing spill, and reduced further when the lower four Snake River dams
are breached,” the draft CSS concludes.
part of the analysis was triggered by two decisions in U.S. District Court in
Portland by Judge Michael H. Simon.
May 2016 Simon rejected the 2014 biological opinion for salmon and steelhead
for the Columbia River hydropower system and ordered a new BiOp be completed by
the end of 2017. In addition to sending federal agencies back to the drawing
board to redo the BiOp, Simon said that in the National Environmental Policy
Act process that was to follow and is currently underway, that the U.S. Army
Corps of Engineers should analyze breaching the four lower Snake River dams as
a reasonable and prudent alternative to retaining the dams.
addition, conservation groups, the state of Oregon and the Nez Perce Tribe
asked for injunctive relief that resulted in court-ordered earlier spring spill
in a January 9 filing, enjoining the BiOp case.
draft CSS study analyzes both dam breaching and spill from a biological
perspective by estimating fish survival benefits of the breaching. It will
leave to others to analyze the costs of breaching.
analyzed four spill levels – BiOp spill; increased spill up to 120 percent TDG
in tailraces of the dams; 120 percent TDG spill; and up to 125 percent TDG
spill, and three flow levels.
Independent Scientific Advisory Board will evaluate the study and its
Chapter 5 of the draft CSS, it examines the association of SARs to life-cycle
productivity for wild spring/summer chinook and steelhead.
population declines of Snake River spring/summer Chinook and steelhead are
associated with SARs less than 1 percent, and increased life-cycle productivity
has occurred in years that SARs exceeded 2 percent,” it says. “Pre-harvest SARs
in the range of 4 percent to 6 percent are associated with historical
(pre-FCRPS) productivity for Snake River spring/summer Chinook. Historical levels
of productivity for John Day river spring Chinook are associated with
pre-harvest SARs in the range of 4 percent to 7 percent.”
“Comparative Survival Study of PIT-tagged Spring/Summer/Fall Chinook, Summer
Steelhead, and Sockeye DRAFT 2017 Annual Report,” can be found at http://www.fpc.org/documents/CSS/DRAFT2017CSS.pdf. Comments should be
sent by October 15 to Michelle DeHart at email@example.com.
study’s project leader is the FPC’s DeHart, but the report is compiled by the
Comparative Survival Study Oversight Committee and the Fish Passage Center.
Contributors include Jerry McCann, Brandon Chockley, Erin Cooper and Bobby Hsu
of the FPC; Howard Schaller and Steve Haeseker are from the U.S. Fish and
Wildlife Service; Robert Lessard is with the Columbia River InterTribal Fish
Commission; Charlie Petrosky is from the Idaho Department of Fish and Game;
Eric Tinus, Erick Van Dyke and Adam Storch are from the Oregon Department of
Fish and Wildlife; and Dan Rawding is with the Washington Department of Fish
June 23, 2017, “Litigants In Salmon BiOp Case Working Together To Develop
Court-Ordered Spill-For-Fish Plan In 2018,” http://www.cbbulletin.com/439147.aspx
May 19, 2017, “Spill Advocates, Federal Agencies Agree To Status Conference
Schedule, Protocol In Salmon BiOp Case,” http://www.cbbulletin.com/438950.aspx
April 7, 2017, “Court Order Requires Earlier Spill For Salmon In 2018; Orders
Design Study, Monitoring,” http://www.cbbulletin.com/438675.aspx
January 19, 2017, “Conservation Groups, Oregon, Nez Perce File To Stop Capital
Projects At Lower Snake River Dams,” http://www.cbbulletin.com/438211.aspx
CBB, January 6, 2017, “Comment Period Extended For Feds’ Scoping On New EIS For
Columbia/Snake River Hydro System,” http://www.cbbulletin.com/438159.aspx
CBB, July 15, 2016, “Judge Gives Feds Nearly Five Years To Complete NEPA
Process For New Basin Salmon/Steelhead Recovery Plan,” http://www.cbbulletin.com/437139.aspx
December 16, 2016, “Scoping Meetings On Basin Salmon/Steelhead EIS End; Next
Step Developing Alternatives For Evaluation,” http://www.cbbulletin.com/438097.aspx
December 2, 2016, “Irrigators Petition Trump Transition Team For ‘God Squad’
Intervention In Salmon BiOp Remand,” http://www.cbbulletin.com/438042.aspx
November 18, 2016, “Hundreds Turn Out For Lewiston Federal Scoping Meeting
Regarding Draft EIS For Snake River Dams,” http://www.cbbulletin.com/437988.aspx
CBB, Oct. 7, 2016, “Agencies Seek Public ‘Scoping’ Comments For EIS Related To
New Basin Salmon/Steelhead Recovery Plan,” http://www.cbbulletin.com/437702.aspx
CBB, May 6, 2016, “Federal Court Again Rejects Columbia Basin Salmon/Steelhead
Recovery Plan; Orders New BiOp By 2018,” http://www.cbbulletin.com/436667