A recently released decade-long study looking at several aspects of water quality, including temperature and sediment, show that current forest practices rules as outlined in the Forests & Fish Law are protective of fish.
Beginning in 2007, the study (informally known as “Hardrock”) measured temperature, sediment and other parameters of water quality three years before a harvest on forestland that is home to non-fish bearing waters that flow into fish bearing waters. Then, for nine years after harvest and during the period of replanting and regrowth, the study continued to measure the same factors related to water quality. Temperatures, specifically, were measured at the height of summer in July and August.
The study found that while there was a small, temporary thermal pulse (averaging 1.2 degrees Celsius) immediately after harvest, stream temperature never exceeded the 16 degrees Celsius threshold established by the Washington Department of Ecology for the most common temperature standard found on private forest lands. Temperature never exceeded 14.2 degrees Celsius – nearly 2 degrees Celsius below the temperature science agrees is needed for the survival of fish including salmon.