Reduce, Reuse, Recycle
New Pilot Project at Leavenworth National Fish Hatchery Thinks Outside the Raceway
Could a change in tank design help hatcheries combat climate change?
By: Amanda Smith, USFWS Columbia Pacific Northwest
Icicle Creek is an iconic stream in central Washington State that runs through the heart of the Okanogan-Wenatchee National Forest into the Wenatchee River, providing life-giving resources to the surrounding communities. From supporting domestic water supply and agricultural irrigation to providing habitat for wildlife and recreation for people, Icicle Creek is in high demand. This hardworking waterway also provides water for Leavenworth National Fish Hatchery, ensuring the creation of millions of salmon annually.
Built in 1940 to make up for salmon loss after the construction of Grand Coulee Dam, Leavenworth National Fish Hatchery is one of three hatcheries that comprise the Leavenworth National Fisheries Complex. Managed by the US Fish and Wildlife Service (Service), the three hatcheries in the Complex — Leavenworth, Entiat, and Winthrop — are visited by 120,000 visitors each year and propagate 2 million Chinook salmon annually. These millions of salmon are produced to fulfill tribal trust obligations, support recreational and commercial fishing, and insure future generations of fish for future generations of people. The Mid-Columbia Fish and Wildlife Conservation Office supports this mission by monitoring and evaluating the work of the hatcheries, as well as helping to restore habitat and monitoring native fish populations and aquatic ecosystems.
Since construction, Leavenworth NFH has been one of many stakeholders sharing the vital resource of Icicle Creek. “Water connects us all,” says Mathew Maxey, manager for the Leavenworth National Fish Hatchery. “We and our federal, state, Tribal, and community partners have a vested interest in conserving Icicle Creek in this time of changing climate while serving the fish and people that rely on it.”
This move towards using less water is a timely one. According to a Climate Change Vulnerability Report due for release later this year by the Service, the next twenty years will alter the flow, temperature, and composition of Icicle Creek and impact the surrounding landscape. These reports assess the vulnerability of National Fish Hatcheries to climate change to help implement proactive strategies for resource management. Here is what data projections show is in store for Leavenworth National Fish Hatchery and the Icicle Creek in the next two decades:
- Warmer water: Surface water temperatures of Icicle Creek are expected to be warmer in all months.
- More rain, less snow: More precipitation will fall as rain and substantially less precipitation will fall as snow.
- Higher flows in winter, lower flows in the summer: High flows will most likely occur in late fall and winter, with lower peak runoff in June, and consistently lower flows in summer.
- Late summer water shortage: Water releases from Snow Lake in August and September would be barely sufficient in the 2040s to meet water right of the hatchery.
- Increased fire risk: Reduced snowpack and less precipitation during the summer in the 2040s are expected to increase fire risks to Leavenworth NFH.
- Increased flood risk: A significant increase in the magnitude of 100-year peak water flows.
- Increased disease risk: Higher water temperatures during the summer are expected to increase disease risks.
While the vulnerability reports may look dire, staff at Leavenworth are thinking outside the box raceway with an innovative pilot project designed to raise fish differently. The complete project offers a way around negative impacts of climate change. Literally.
Typically, once salmon have hatched and reached the “fry” stage, staff transfer them into 44 long, straight, concrete channels called raceways, where the fish will spend 11 months growing before their release into Icicle Creek the following April. From there, their migratory journey begins and they will spend two months making their way to the ocean before returning home to spawn in 2–4 years. This system is efficient at propagating healthy salmon — evidence by the thousands of fish that return to the hatchery every year. So if there is nothing wrong with this system, why change it? This is precisely the question I posed to Hayley Muir, fish biologist at the Mid-Columbia Fish and Wildlife Conservation Office.
“Raceways are effective for rearing large numbers of fish and have served us well for many decades,” Muir said. “Yet we have data showing that changing from a raceway to circular tanks may increase fish health while decreasing our water usage and increasing discharge water quality.” Known in the fisheries world as Partial Recirculating Aquaculture Systems (PRAS), these circular tanks move water around in a whirlpool-like motion allowing for most of the solid waste to be removed from a drain in the center of the tank. Cleaner water is removed from a drain on the side of the tank, filtered, stripped of carbon dioxide, UV treated to remove pathogens, re-oxygenated, and is returned to the tank. The ability to recondition and reuse the water has increased the potential PRAS offers in terms of water conservation.
Currently, Leavenworth NFH diverts about 18,000 gallons of water per minute in the propagation and rearing of Chinook salmon. “We accomplish a lot with that water and yet we are always looking for ways to reduce our impact on Icicle Creek,” said Matt Cooper, a fisheries biologist working with Muir on the project. “We take our responsibilities as stewards seriously.”
This scientific seriousness on a small pilot project could mean big water savings in years to come. “It is no secret that our climate is changing and we need to think now about the future,” said Cooper. The project leads estimate that if the PRAS pilot project goes as expected and the hatchery begins to adopt circular tanks, they will be able to put 50 percent more water back into Icicle Creek.
Rearing fish in PRAS is not new to the fish culture and has been successful for decades. However, rearing the notoriously finicky spring-run Chinook Salmon in a PRAS system will be new territory not only for Leavenworth NFH but for hatcheries throughout the Columbia River Basin.
The PRAS pilot project is scheduled for completion later this summer, there will be a three year evaluation comparing PRAS to the traditional raceways. The evaluation will address if PRAS can rear smolts as well as the conventional raceways, maintain high water quality, mitigate disease risk, sufficiently reduce water usage, and meet effluent requirements. If the answer is “yes” to these metrics, the hatchery will move forward with rearing all of the production in a PRAS setting — meaning the continued production of millions of fish and massive water savings for the iconic Icicle Creek.