Many factors have contributed to declines in Northwest salmon populations. By the 1940s, Columbia River salmon runs were in serious decline. Particularly, harvest in the lower river took a huge toll between about 1870 and 1920. By the time Bonneville Dam was completed in 1938, adult salmon returns numbers were already at crisis levels. However today, improvements at the dams, habitat restoration, and hatchery reforms are working together to benefit salmon.
In fact, Northwest families and businesses have been helping fund fish and wildlife mitigation through their electricity bills. Since 1981, BPA has spent close to $17 billion on fish and wildlife-related activities that were funded through their customers. As of 2017, approximately 33% of the Bonneville Power Administration’s wholesale power rate is associated with its Fish and Wildlife related programs. For customers who buy power from a BPA-sourced utility, around 15% to 20% of their typical utility bill goes towards these programs.
Additionally, as part of the Columbia Basin Fish Accords, approximately $100 million a year since 2008 has gone towards the Northwest states and tribes. The money is used for improvements to habitat in river tributaries and the Columbia River estuary. These improvements include repaired, enhanced spawning grounds for salmon.
Through these funds, new fish protections have been put into place at all eight lower Columbia and lower Snake River dams. Examples of protections include fish bypass systems, such as removable spillway weirs. These new structures have increased the survival of juvenile salmon. The survival rate past each dam ranges from 93% to 99%, depending on the fish species.
To help the migration of juvenile salmon in the spring, the recently passed Flexible Spill Agreement has led to increased spill of water over the lower Columbia and Snake river dams in certain hours of the day. This agreement seeks to move young fish downstream faster. Young fish are also barged around dams to help them avoid turbines and increased predation.
What is the outlook for the future of salmon?
While salmon returns vary greatly year-to-year, this past decade saw a major increase in the number of adult salmon that returned to the Columbia and Snake rivers. We have seen record and near-record salmon runs in that time frame compared to historical records that date back to 1938. Hatcheries, fish passage improvements at the dams and habitat improvements have likely all played a role in helping to achieve these greater numbers.
Unfortunately, the latter half of the past decade was less promising. Ocean conditions became very poor as a result of a high pressure system that significantly raised water temperatures. Luckily, the Pacific Ocean is shifting from several years of unusually warm conditions toward a cooler and more productive state. Per a NOAA Fisheries report from March of 2019, that change is expected to boost salmon returns, barring any unusual events.