Federal authorities have initiated spring fish passage operations at dams along the lower Snake and Columbia rivers, moving forward with a controversial set of water management protocols designed to protect endangered salmon and steelhead. According to the U.S. Army Corps of Engineers, operations began on April 3 at federal dams on the lower Snake River and followed on April 10 on the lower Columbia River.
The timing and execution of these spring fish operations are governed by a combination of NOAA Fisheries’ 2014 Supplemental Biological Opinion and a series of recent federal court mandates. These measures aim to accelerate the migration of juvenile fish toward the Pacific Ocean, reducing the time they spend navigating the complex system of dams and providing critical non-turbine passage routes to avoid lethal turbine strikes.
At the center of this year’s operations is a February order from U.S. District Court Judge Michael Simon, which requires the Corps to increase “spill”—the process of releasing water over dam spillways rather than through turbines—and lower reservoir levels. These adjustments are intended to create a more natural flow for juvenile fish, though the strategy has sparked a legal battle between environmental advocates, federal agencies, and regional stakeholders.
The Legal Conflict Over Water Spill
The current operational phase is fraught with tension, as the federal government and various dam stakeholder groups have filed appeals to seek a stay of Judge Simon’s order. Those opposing the mandate argue that the increased spill poses significant risks to public safety and critical infrastructure. Stakeholders contend that there is insufficient substantiated evidence to prove that these specific changes will provide a measurable benefit to endangered salmon and steelhead populations.
Despite these appeals, the Corps is proceeding with a spill strategy that may push the boundaries of regional environmental regulations. This year’s operations involve sending water over spillways at levels that could reach up to 125% of the state water quality limits for total dissolved gas (TDG) in both Oregon and Washington. High levels of TDG can be harmful to fish, creating a precarious balancing act for engineers trying to facilitate passage while maintaining water quality.
Judge Simon acknowledged the complexity of these trade-offs in his February ruling. In addressing the potential negative impacts on other species, specifically the bull trout, the judge described the existing record of evidence as “limited, deeply contested and less well-established.”
“Simply weighing the number of species, the lone bull trout to the 14 listed species weighs in favor of protecting the many over the one,” Simon wrote in the order. “More importantly, the relief sought for the salmon and steelhead tracks the best practices articulated in this case’s quarter-century-long record.”
Water Supply Forecasts for 2026
The effectiveness of these fish passage operations is heavily dependent on the available water volume in the basin. For 2026, the U.S. Army Corps of Engineers has issued forecasts that show a divergence between the two river systems. While the Columbia River Basin is seeing “near-normal” conditions, the Snake River Basin is experiencing “below-normal” conditions, which may complicate the effort to maintain lower reservoir levels while ensuring enough spill for fish migration.
| Location | Forecast Period | Percentage of Normal | Condition |
|---|---|---|---|
| The Dalles Dam | April through August | 93% | Near-Normal |
| Lower Granite Dam | April through July | 73% | Below-Normal |
Environmental Risks and Species Impact
While the primary goal of the operations is the survival of salmon and steelhead, the Corps has warned of potential collateral damage to other Endangered Species Act-listed fish. Matt Rabe, regional director of public affairs for the Corps’ Northwestern division, stated in court filings that there is a potential for impacts to adult salmonids migrating upstream and bull trout, depending on the duration and intensity of the spill over the coming months.
The tension reflects a broader, decades-long struggle over the management of the Northwest’s river systems. The 2014 Supplemental Biological Opinion remains a cornerstone of these operations, but the intervention of the federal courts indicates a growing judicial impatience with the pace of salmon recovery. By prioritizing the “many over the one,” the court has signaled a preference for broad-spectrum species protection over the specific concerns of a single listed species like the bull trout.
For the juvenile fish currently moving downstream, the stakes are immediate. Lowered reservoirs reduce the “slack water” effect, allowing juveniles to move more quickly and reducing their exposure to predators and temperature stress. But, the risk of gas bubble disease—caused by the very spill intended to save them—remains a primary concern for biologists monitoring the 125% TDG thresholds.
As the season progresses, the U.S. Army Corps of Engineers will continue to implement additional support actions for salmon and steelhead as required by the current biological opinion. The agency remains the primary authority for real-time updates on dam operations and water levels across the lower Columbia and Snake river systems.
The next critical phase will involve the resolution of the pending appeals filed by the federal government and stakeholder groups. A decision on whether to grant a stay of Judge Simon’s order would fundamentally alter the spill volumes and reservoir levels for the remainder of the spring migration window.
This report is for informational purposes and does not constitute legal advice regarding the Endangered Species Act or federal water rights.
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