Rewilding the Lower Snake River: A Comprehensive Look at the Benefits Beyond Salmon Recovery

The Seattle Times recently posed a crucial question regarding the potential removal of the Lower Snake River Dams and the impact on salmon populations. The response goes far beyond salmon conservation, delving into the multifaceted benefits of rewilding a crucial waterway.

The lower Snake River, located in southeastern Washington, holds immense value beyond safeguarding wild salmon and steelhead from extinction. The cultural and ecological significance of restoring this river to its natural state far transcends the advantages of maintaining it as a reservoir.

Before the Lower Granite Reservoir was established in 1975, the lower Snake River boasted a diverse ecosystem. The region lost 14,400 acres of bottom lands, 1,125 acres of island habitats, and 1,123 riparian acres to the reservoir, covering 90,000 surface acres.

In the 1950s and 1960s, the lower Snake River was characterized by sandy beaches, abundant sturgeon fishing spots, and lush riparian zones teeming with chokecherries, hackberries, and mulberry trees. The riparian habitat supported a variety of wildlife, including pheasants and quail. The river’s intricate network of channels and islands provided a rich tapestry of natural diversity. Additionally, the area was dotted with farms, fruit orchards, and numerous cultural sites.

An archaeological milestone occurred in 1965 with the discovery of the Marmes Rockshelter, dating back 10,000 years before the present. Situated at the confluence of the Palouse and Snake rivers, the rockshelter’s historic significance was highlighted by the failed attempt to protect it from flooding by the Army Corps of Engineers during the filling of the Lower Monumental Reservoir in 1969.

Prior to the river’s impoundment, Lewis and Clark documented 63 named rapids along the lower Snake River in October 1805, underscoring its dynamic and vibrant nature.

Impoundment, resulting in slack water, significantly alters the natural flow and characteristics of a river. Reservoirs reduce water velocity, alter sediment transport, raise water temperatures, and disrupt floodplains, leading to a fragmented river system.

The four dams on the lower Snake River are run-of-river dams, lacking significant storage capacity or flood control. Collectively, these dams create 140 miles of slack water, transforming what was once a thriving, functional river into stagnant reservoirs. Migrating juvenile salmon rely on strong water currents to carry them towards the Pacific Ocean, enhancing their chances of survival.

Studies suggest that removing the lower Snake River dams could mimic the successful restoration efforts seen on the Elwha River in Washington’s Olympic Peninsula, with short-term setbacks giving way to long-term benefits. Scientists like John McMillan from Trout Unlimited envision a rewilded lower Snake River evolving into a river with natural features such as islands, side channels, riffles, pools, and rapids. The restoration of gravel bars connected to groundwater would create cold-water refuges, further enhancing the ecosystem.

Rewilding the lower Snake River isn’t just about salmon recovery; it’s about revitalizing an ecosystem for long-term sustainability. With climate change exacerbating the impacts of the existing reservoirs along the 140-mile stretch, restoring the river to its natural state holds promise for a healthier environment.

Recent events, such as a 30-mile toxic blue-green algae bloom in the lower Snake River in the fall of 2023, underscore the detrimental effects of dammed waters. Experts like Alex Fremier from Washington State University highlight the link between damming rivers and toxic algae blooms, noting the absence of such blooms in the free-flowing sections of the Snake River above the reservoirs.

NOAA‘s report on ‘Rebuilding Interior Columbia Basin Salmon and Steelhead’ outlines numerous benefits of rewilding the Lower Snake River. The removal of the dams would enhance floodplain connectivity, restore natural sediment distribution, and improve riparian habitats for a wide range of aquatic and terrestrial species. It would also facilitate spawning for species like white sturgeon and fall Chinook salmon, while facilitating free-flowing migratory pathways for bull trout, lamprey, and sturgeon. The report emphasizes the diverse and long-term advantages that a restored river ecosystem can offer, especially in the face of climate change.

Moreover, the restoration of natural riparian conditions post-dam removal would benefit terrestrial species like deer, waterfowl, and amphibians. By fostering the growth of cottonwood galleries and other riparian vegetation, the improved habitat conditions would support avian species such as ospreys, eagles, and herons, enhancing biodiversity along the river.

Ultimately, the rewilding of the lower Snake River emerges as the most holistic solution, benefiting not just wild salmon and steelhead but the entire ecosystem. Transitioning from a series of unhealthy reservoirs to a thriving, free-flowing river promises lasting environmental and ecological gains for current and future generations.