Situated on the Pend Oreille River north of the Metaline Falls in Washington state is Boundary Dam, a 340-ft-tall concrete arch hydroelectric dam first built in 1967 that can generate 1,117 MW of power. When the facility’s license with the Federal Energy Regulatory Commission (FERC) was up for renewal in 2009, owner and operator Seattle City Light (SCL) agreed to review related impacts to threatened or endangered species as part of the re-licensing settlement for the new 42-year license.

As part of this effort, SCL worked with HDR and Lydig Construction to design and build a $27-million state-of-the-art facility that now helps to protect and establish the self-sustaining, naturally producing and threatened westslope cutthroat trout population in the Pend Oreille River watershed. To do that, the facility captures genetically pure fish from the basin's tributaries, spawns them and returns their progeny to the natal streams. It also eradicates non-native species.

Scope of work included significant underground utility installation along with eight facility structures that include a new shop and storage building, an administration building, truck disinfection and fill station, pump station, pollution abatement pond, water treatment building and discharge structure. The facility also features a bunkhouse for visiting scientists and two residences for full-time staff.

An interior view of the Westslope Salvage Building, which houses many of the facility’s rearing tanks.
Photo by Chris Thompson Photography

Underground Challenges

The number of westslope cutthroat trout has plummeted by about 90% across the region, nearly qualifying the fish as endangered. Species restoration is the exclusive goal for this conservation facility, where advanced aquaculture techniques will help caretakers rescue and nurture trout from local streams.

The Native Salmonid Conservation Facility relies on real-life stream conditions and careful attention to population genetics to produce the highest-quality fish possible. The hatchery features two steel-framed fish-rearing buildings, each with circular fiberglass tanks, which are kept at optimal conditions for the trout throughout all stages of their life cycle. A third building will eventually be built to help restore the area’s bull trout populations as well.

“The water supply is very cold, which is not very suitable for a typical sport fish production hatchery, but [it] is perfectly suitable for westslope cutthroat trout,” says Mark J. Hassebrock, project manager at HDR.

Skookum Creek provides frigid water, which is diverted to the facility’s pipe and control vault. It is then mixed with spring water from a buried collection pipe system to create the ideal temperature for the fish. To prevent contamination, water is purified before moving into the hatchery tanks, and then after running through the facility, water returns to the creek. During low flow periods, a pump system will return diverted water back to the point of withdrawal to limit impacts.

This site was home to an older hatchery—demolished to make way for the new structures—that utilized a small concrete dam to impound spring water. However, with no as-built drawings available, its depth remained a mystery. Crews quickly realized when beginning work on the spring collection piping that the toe of the dam was just a few feet underground, making the structure unstable. To resolve the issue, the team collaboratively designed and built a 20-ft-deep sheet-pile replacement dam, which allows the structure to capture far more spring water than before. This improved capacity will also provide the facility with ample water resources in the future, should the area face groundwater loss as a result of climate change.

With shallow groundwater to contend with as well, the team faced some difficulties during installation of both the foundations and two large fire suppression storage tanks. Constant pumping was necessary to maintain subgrade conditions during excavation. With the help of its geotechnical consultant, the team stabilized the excavations by using a combination of quarry spall rock and geotechnical fabric.

The Washington Dept. of Fish and Wildlife helped support habitat restoration and management as part of the project. Native plantings will help replenish sensitive areas and buffers.
Photo by Chris Thompson Photography

Lots of Water

Although the fish propagation facility’s primary goal of restoring native aquatic species is a sustainable one, one of the most significant costs for a facility like this is for all the power necessary to pump the water supply through the various stages of the process. Thanks to the site’s natural slope, the team was able to embrace gravity flow when designing the creek and water supplies, which eliminated the need for continuous pumping and associated power.

But another water consideration was ensuring that the full-time staff on site had access to a domestic water supply—permits for which were difficult to obtain in this location. To do so was a bit of a catch-22. To meet health regulations for domestic water, the team had to prove that the site’s well was not hydraulically connected to nearby Skookum Creek. However, the team had to go ahead and drill the well in order to find out if there was even a water-bearing stratum deep enough so that the well would not be hydraulically connected to the creek.

These facilities can sometimes negatively impact other wild fish as well. The old hatchery relied on a small timber crib dam in the Skookum Creek channel that moved water into the facility, but the Washington Dept. of Fish & Wildlife (WDFW) identified that dam as a barrier to fish passage. For the Native Salmonid Conservation Facility, crews removed the old dam and used a stabilized natural channel design to restore about 260 ft of creek habitat. WDFW also helped support habitat restoration and management as part of the project, with native plantings that will help replenish sensitive areas and buffers.

Along with helping fish, this project included scope to help some creatures above ground as well. One of the old smaller structures on site was a maternal roosting site for endangered Townsend’s big-eared bats. One of the project’s goals was relocating the roost to the north end of the property, where it wouldn’t be disturbed by hatchery operations. After consulting with chiropterologists on the best mitigation strategies, the team built a new roost dimensionally identical and oriented like the old structure, which bats have already been observed using.

All About Collaboration

One of the team’s biggest challenges “was trying to implement a project during the height of COVID restrictions and supply chain issues,” says Harry Rich, fisheries biologist and project manager at SCL.

Working in tandem with SCL, the HNTB and Lydig team focused on finding solutions with greater constructibility in the field while maintaining the original design intent. Catching potential issues early allowed crews to quickly resolve problems, saving time and rework costs.

“The contractor, design consultant, owner and construction management teams all coalesced into a strong combined team that developed a high level of open communication and respect for the wide range of valuable knowledge, experience and expertise that individual members brought to the team,” Hassebrock says. “Creative problem-solving became a common occurrence.”

Lydig also prioritized safety and put additional emphasis on injury prevention because the underdeveloped site’s remote location would make seeking medical care difficult. To keep workers safe during extreme weather conditions amid rough terrain, the contractor employed Yaktracks clamp-on traction devices to prevent slips and falls throughout two long winters. To combat muddy conditions in the spring and fall before paving was in place, ramps were covered with chicken wire to stabilize the surface. Efforts like this helped the team achieve 67,298 worker hours with no lost time or recordables.

An extensive stormwater pollution prevention plan helped protect the native areas and streams from impacts related to heavy construction on site. A certified erosion and sediment control lead (CESCL) consultant worked alongside Lydig’s CESCL staff to help the project exceed stormwater pollution prevention requirements.

On May 29, SCL and other stakeholders, including WDFW, the Kalispel Tribe of Indians, U.S. Fish and Wildlife Service and Pend Oreille Public Utility District celebrated the facility’s grand opening.

“The biggest reward [on this job] was building solid relationships between the owner, design/engineering firm and contractor that allowed all team members to trust each other, overcome challenges and deliver an amazing project,” Rich says.

SCL expects to operate the new hatchery for decades, and the facility is already breeding and rearing trout. Initially, it will have the capacity to produce up to 12,000 trout eggs, fry or fingerlings per year and multiple age class broodstock.

“It was not previously very well known if westslope cutthroat trout captured in the wild would take feed in captivity,” Hassebrock says. “Now that the facility is operational with live fish, the operators are having success with live feed consisting of worms and bug larvae that are being cultivated at the facility.”