Friday, December 14, 2012

Ten Million Fish, Part II

In July 2012, it became apparent that Rapid River hatchery (Idaho Department of Fish and Game operated for Idaho Power) was not going to meet their necessary broodstock for spring Chinook salmon. The co-managers requested that Dworshak take an additional 2 million eggs to make up the shortfall. To accomplish this Dworshak would need to collect an extra 500 females at spawning and use twice as much water in incubation than in years past. Rapid River has backfilled Dworshak when they have not met broodstock in the past.
Adult Chinook salmon ready to spawn

In August 2012, the intake for the Clearwater Hatchery pipeline failed. Several reps from the Corps were at Dworshak the day of the failure and received backing from the Portland office to completely support any efforts to save fish production at Clearwater Hatchery. One week after the failure, all 2.5 million Chinook smolts from Clearwater Hatchery were safely moved to Dworshak in 25 Burrows Ponds in System 3. To accommodate these additional fish, Dworshak consolidated the Steelhead into 5 ponds in System 3 (and 50 in Sys 1 and 2) and the Coho into 4 ponds in System 3. Dworshak is also operating under the premise that when the pipeline is repaired by January 2013, they will receive an additional 25 cubic feet per second (cfs) of water to support the Chinook smolts through final rearing.

Dworshak Dam / Credit: ACOE

When the Clearwater Chinook production came to Dworshak, several key changes happened to wastewater management at Dworshak:

1) The staff created a cross connect from the System 3 re-use main aeration to the ladder discharge. This allowed the used of the defunct biofilter system to skim clean water through the launders and discharge it to the river during cleaning operations
2) The media from System 2 that had breached the screens was removed and taken offsite. This allowed the cross connection of System 2 and 3 biofilters through the old effluent pipeline and increased the capacity of the treatment pond
3) Cleaning protocols changed to incorporate large numbers of staff to maximize availability of the treatment pond space. We currently clean System 3 with a minimum of 10 staff members at a time
4) A cross connect was installed to alleviate excess water from System 2 and 3 out to the Clearwater river discharge rather than the ladder. This allowed the higher flow rates to be maintained in all 34 ponds in System 3 as compared to the 9 ponds utilized in 2011.
Cleaning System III Burrow's Ponds

Because of these changes, EPA recommended that the intent of the FFCA agreement had been reached. Necessity had genuinely inspired innovation! This opened the door for future rearing back in System 3 and allowed the continued use of System 3 to finish rearing the Clearwater Chinook smolts in 2013. The EPA hasn't provided anything officially stating we are in compliance, but have verbally supported our efforts to increase Chinook production this year under the emergency situation with the failure of the primary pipeline. They have also verbally supported us to increase production in the future based on our water quality data for how we are now able to operate system III.  Included in this effort, it is essential we follow through with the interconnections of System II and III and the pumps to pull supernatant from higher in the water (a float system will accomplish this) column to maximize the opportunity for solids to settle. 

Eyed Chinook salmon eggs

In September 2012, it became apparent that Rapid River Fish Hatchery had higher Spring Chinook fecundity and returns than expected. As such, they only needed 600K of the 2million eggs requested from Dworshak. Dworshak staff consulted with the co-managers; Corps, Tribe, LSRCP (Lower Snake River Compensation Program), and IDFG about rearing these additional eggs to smolts in System 3 during 2013. These additional smolts would help address shortfalls to the LSRCP program for Spring Chinook returns. All the co-managers were supportive of this increased production, if it did not affect the health or performance of current smolt releases. The Corps recommended a real estate agreement for this production increase.
Clearwater Hatchery Chinook to be release from Dworshak in the spring, 2013

I think this brings us back to today. We have a record number of fish and eggs on-station at Dworshak. We have staff from 4 entities (Corps, Tribe, FWS, and IDFG) actively working at Dworshak daily to make this endeavor a success and we are cautiously optimistic that all smolts will be released in great shape. We are currently battling some BKD issues in the Clearwater Chinook in Systems 3, but mortality from the outbreak is low and the outbreak has been attributed to hauling stress from IDFG Fish Health professionals. We did not have any IHN epizootics in steelhead production this year, and the Coho and Raceway Chinook continue to do great!

Text by Nate Wiese
Photos (unless noted) by Angela Feldmann

1 comment:

  1. Wow! What an operational change and outstanding job. Thanks for the update.