Scientists Tell Council Proposed Spring Spill Experiment
Could a controversial proposal to boost springtime spill at mainstem Columbia and Snake river dams add to knowledge regarding spill, juvenile dam passage survival, and adult fish returns?
Yes, Independent Scientific Advisory Board members told the Northwest Power and Conservation Council Wednesday. But the proposal at this point lacks definition in a variety of areas, and is not yet ready for primetime.
"Alternative approaches, including the spill concept, are worth exploration and discussion," ISAB Vice-chair Greg Ruggerone said. But the proponents who recommended the spill-boost experiment lack a detailed study plan by which it can be judged.
Ruggerone and fellow ISAB member Alec Maule this week discussed with the Council the findings from the ISAB's Feb. 20 "Review of the Proposed Spill Experiment," which can be found at: www.nwcouncil.org/fw/isab/isab2014-2.
Various parties, NPCC Chair Bill Bradbury of Oregon noted, have claimed the ISAB review supports the spill proposal, or on the other hand, shoot it down.
The short-term answer, Ruggerone told the Council is that "at this time it is not adequately described" to assess whether or not it should be implemented.
He said proponents would need to produce a detailed research plan, and answer a flood of critiques that followed the proposal's submittal to the NPCC's program amendment process.
Boosting smolt-to-adult return rates to the Columbia River basin is an established goal of the Council program. How that might be done is open for scientific debate.
"I think there's a good dialogue taking place" regarding the particular merit of an increased spill experiment, Ruggerone said. The ISAB was formed to provide analysis of scientific issues on request from the NPCC, NOAA Fisheries, and/or Columbia River basin Indian tribes.
The spill proposal submitted to the Council last year is supported by the state of Oregon, the Nez Perce Tribe, the Pacific Fishery Management Council and environmental and fishing groups and individuals.
If the recommended implementation of increased spill as an experiment takes place, dissolved gas waivers issued by Oregon and Washington would have to be revised upward.
More spill means more dissolved gas would be created in the water. Higher levels of TDG can cause health problems for fish and other aquatic species.
Spill increase proponents say that ushering the young salmon and steelhead more speedily and benignly toward the ocean through spill would improve in-river survival, and boost "smolt-to-adult returns" closer to desired levels.
A recommendation submitted by Bonneville Power Administration customer groups and utilities anticipated the proposal and adamantly oppose it, according to a summary of recommendations produced by the NPCC staff.
Power customer interests say such a spill test would be illegal, and is inappropriate and unnecessary and could do fish more harm than good through increased TDG and potentially increased levels of spawner "fallback" through spill gates.
They say spill levels outlined in NOAA Fisheries' Federal Columbia River Power System biological opinion reflect the best available science on spill and the transportation of fish downstream via barges. The BiOp judges whether the dams and their operations jeopardize the survival of salmon and steelhead stocks that are listed under the Endangered Species Act.
A recent BPA analysis says such a spill test, proposed for implementation over 10 years, would lead to an annual loss of $110 million per year in power sales. Water spilled instead of flushed turbines represents foregone power generation and sales.
The proposal calls for an increase of spill levels from April 3 through June 20 to levels that raise TDG to as much as 125 percent, an increase from waiver ceiling typically that have been at 110 percent in the forebay and 115 percent in the tailrace at mainstem lower Columbia and Snake mainstem dams. The experiment described in the proposal would be conducted for 10 years, with a review scheduled after the first five years of implementation.
The experiment would involve monitoring of smolt-to-adult survival rates, and comparisons of survival rates with past values and model predictions. The proponents say it would also include "off-ramps" to ensure hydrosystem viability and "on-ramps" to offset reduced hydropower generation.
Spill proponents predict that on average SARS would be boosted to 3.5 percent (the percent of outgoing smolts that return as adult spawners) for chinook and about 4 percent for steelhead.
Observed SARs with current spill regimes are just over 1 percent for chinook and just under 2 percent for steelhead.
"That's a huge increase," Ruggerone said of the projected SARs. In past NPCC programs, a goal has been set of achieving SARs of from 2 to 6 percent, but few populations actually reach that range.
The ISAB review says the proponents need to build a detailed study plan that includes:
The ISAB said there is also a need to better understand potential biological risks such as:
"You don't do a billion dollar experiment if it's a long shot," said Washington Council member Tom Karier.
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