PNNL

The cool waters of the Columbia River bring relief to many during our hot Tri-Cities summers. But while you might be boating, floating or watching hydroplanes, researchers at the Department of Energy’s Pacific Northwest National Laboratory are studying the river and protecting the fish that call it home.

With a field site of more than 40 miles of the Columbia’s Hanford Reach, PNNL researchers are advancing the understanding of the interconnected hydrological, biological, geological and chemical systems of the river corridor and watershed.

In studies supported by DOE’s Office of Biological and Environmental Research, they are looking at areas where flowing river water mixes with shallow groundwater, known as hydrologic exchange flows or HEFs. The thermal and biogeochemical dynamics in HEFs are important to river ecology and affect spawning fish habitat, food production and pollutant removal.

Due to seasonal and daily changes in water flow caused by snowmelt and dam operations, the Columbia experiences fluctuations in water levels and temperature, as well as the location, size and direction of HEFs. Relying upon a network of more than six miles of wires, sampling tubes and sensors, scientists can monitor physical structures, hydrologic fluxes, biogeochemical conditions and microbial communities.

They are improving the ability to predict HEFs, their complex processes and how they are impacted by changing conditions. They also are creating mathematical models that represent the influences of HEFs at local scales and predict their cumulative impact at the watershed level.

In one project, researchers determined that frequent fluctuations and low flow conditions led to warmer waters, increased carbon consumption and higher rates of microbial activity in river sediments — all of which increase even more in times of drought. Studies like these help ecologists more accurately assess the impacts of long-term, frequent variation in water flow from dam operations and can inform decision-making for managing them.

The same research team works with the global community to understand river corridors worldwide through a PNNL-led international consortium. The Worldwide Hydrobiogeochemistry Observation Network for Dynamic River Systems — known as WHONDRS — focuses on improving scientific understanding of river corridors throughout the world to improve our ability to predict impacts of disturbance across all watersheds, including the Columbia River. 

When it comes to fish, PNNL has led efforts to better understand the Columbia Basin’s juvenile Chinook salmon and steelhead populations. Our researchers, supported by the U.S. Army Corps of Engineers and DOE’s Water Power Technologies Office, have developed two technologies to learn about the behavior, movement and survival of these fish as they migrate from freshwater, past hydroelectric dams and back to the ocean.

The first involves implanting fish with tiny acoustic tags, each emitting a unique series of beeps that are picked up by receivers in the river as the fish swim past. The data collected help researchers map the three-dimensional location of each fish, determining the path and duration of its journey, encounters with structures and predators, and injuries or fatalities along the way.

The second technology for studying the Columbia’s fish is Sensor Fish. This PNNL-developed, instrumented device takes more than 2,000 measurements per second, gathering information about the conditions real fish encounter as they move through water and around dams or other structures.

The scientific data collected by both technologies can help inform and improve turbine designs, dam operations and downstream passage strategies to increase survival rates. This means that we can benefit from the river’s clean hydroelectricity without harming the salmon we all love.

Splashing, paddling, cruising and casting in the mighty Columbia are great ways to spend a summer day off. However, for PNNL scientists, studying the river and protecting its fish are all in a day’s work.