Innovative solution supports mussel restoration

In northeast Oregon in the U.S., the Confederated Tribes of the Umatilla Indian Reservation (CTUIR) is managing a project to replenish freshwater mussels, a "First Food" of the tribes. The project involves growing thousands of juvenile mussels in a laboratory, but providing them with the right levels of nutrients and water was a challenge. Now with Xylem's Flojet pumping solution, 95% of the mussels survive to six weeks, compared to 30% before.

The CTUIR is a sovereign governmental nation made up of three Native American tribes - Cayuse, Umatilla, and Walla Walla. In the 1855 Treaty of Walla Walla, CTUIR ceded 6.4 million acres of homeland in what is now northeastern Oregon and southeastern Washington. They retained rights to hunt, fish and gather First Foods, an indigenous term for traditional foods that are native to the community such as freshwater mussels, salmon, elk and deer.

Today, the Umatilla Indian Reservation spans 172,000 acres, including a significant portion of the Umatilla River Watershed. While the three-tribe confederation has a population of 2,900 people, the tribes have been impacted by severe habitat degradation due to overfishing and hunting, and land use changes. Now, many of the First Foods relied upon for sustenance are at serious risk of becoming endangered. To return these foods to self-sustaining and harvestable levels, CTUIR have commenced several research and restoration projects.

Photo: USFWS/C. Newlon

Researching and growing freshwater mussels

One such project is the Freshwater Mussel Research and Restoration Project - the first of its kind in the western U.S. Freshwater mussels are extremely understudied worldwide, especially in the western U.S where very few species remain. In 2002, CTUIR began an ambitious restoration project using historical data to determine what mussels resided in its home river, the Umatilla River, before expanding to other rivers in the area.

More than two decades later, CTUIR has the longest running freshwater mussel restoration project in the western U.S., and the only dedicated freshwater mussel propagation laboratory for western mussels, including the western ridged mussel - a rare species specific to the western region. This year, CTUIR's laboratory propagated around 4,000 western ridged mussels, and more than 8,000 mussels have been propagated under the restoration program in total. Today, there are currently more than 2,000 juvenile mussels across three different species in CTUIR's laboratory.

Photo: Alexa Maine, Confederated Tribes of the Umatilla Indian, Reservation Freshwater Mussel Project.

Raising thousands of juvenile mussels in a laboratory requires meticulous control. The equipment and cultivation environment has to be just right. To aid successful and sustainable propagation, CTUIR deployed an innovative system that simplifies the processes involved with culturing juvenile mussels. A central challenge of captive culture is maintaining adequate food levels while ensuring appropriate water quality - particularly for newly metamorphosed and juvenile freshwater mussels that are small and delicate.

The system deployed by CTUIR addresses those challenges by optimizing the flow of water and nutrients, aiding the slow but steady growth of the freshwater mussels.

Xylem's Flojet solution provides optimal flow rate

To support the system, CTUIR required a pumping solution that could handle the right rate of flow while moving the fresh water up 10 feet from the reservoir to the dosing subsystem. Designers of the original system recommended Xylem's innovative Flojet 02840 Series, a light-duty water boost system that provides constant water pressure and is known for its reliability and flexibility. As a standalone solution that does not require external plumbing, the system can easily scale as the mussel restoration project advances.

"Xylem's Flojet solution has solved a lot of problems for us," said Alexa Maine, Aquatic Propagation Lab Supervisor at CTUIR. "When deploying the rearing system in our lab initially, it was incredibly difficult for us to identify the correct flow rate while ensuring the pumps could get above the required head length. Trying to plumb it any other way would have been way more expensive than the system itself."

Prior to installing the pumping solution in 2022, laboratory staff at CTUIR had to raise the freshwater mussels by hand, feeding them up to 18 times a day as juvenile freshwater mussels need constant food and fresh water to survive.

Now that CTUIR has a reliable pumping system that automatically triggers a pulse flow once an hour, every hour, the mussels have a finite way of receiving the correct dosage of nutrients and water without risking their growth progress. Since implementing the technology, the survival rate of the freshwater mussels has increased from just 30% at six weeks, to 95% at six weeks.

"I've been doing this close to 10 years now, and for 8 of those years I experienced significant mortality rates, with only 30% of the freshwater mussels surviving until six weeks," said Maine.

"To go from that to a 95% survival rate is absolutely unheard of - other labs that are involved in mussel restoration might only get a survival rate of 60% at best. The Flojet pumps have been transformative for us, and I can assure you that this rearing system is setting the gold standard for mussel propagation efforts going forward."

Moving the mussels to a pond system

CTUIR are now looking ahead to the next phase of the restoration project, which will involve the "out-planting" of the lab-reared mussels into their natural habitat in the wild. When the mussels reach a taggable size - around 20-30 millimeters - they will be moved into a pond system with access to food and a temperature regime that replicates their natural environment.

Should the initial pilot phase be successful, a full out-planting of the mussels will take place. From there, they will continue to be tracked until they become fully reproductive, which for some species could take up to seven to ten years. If they persist in the wild, this will create a new population to effectively restore harvestable levels of freshwater mussels.

"We are in year 10 of our mussel restoration project and we've learned quite a bit about mussel propagation," said Maine. "However, since installing our cultivation technology, we've been able to move much further, at a faster rate. We've achieved more over the last two years than we did in the first eight. And so theoretically, within my career lifetime, we may see the full restoration of some freshwater mussel populations, and we may see our first full harvest for tribal members in several generations."

"We're honored to have supplied CTUIR with our renowned Flojet system in support of this impactful work," said Alaina Celeste, Business Development Manager, Sustainable Solutions at Xylem. "It's amazing to think that this solution has advanced progress in juvenile mussel survival rates far beyond what was ever achieved before. Projects like this are critical to the health and prosperity of tribal communities in the western U.S. and we're happy to support CTUIR in any way we can."

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