The enactment of the Washington Clean Energy Transformation Act on May 7 expanded hydropower’s role in addressing the decarbonization of the state’s power supply, by letting it directly count toward the act’s 2030 carbon-neutral and 2045 carbon-free mandates.

The new law, passed as Senate Bill 5116, allows existing hydroelectric generation to meet the new energy standards, as long as it doesn’t come from new diversions, impoundments, or expansions of existing reservoirs after the date of the act.

It also allows energy from new pumped storage—which might create new impoundments, diversions or reservoir expansions—to meet the new standards, as long it complies with state and federal fish recovery plans or other laws and regulations.

Previously, the use of hydro to decarbonize the state’s electricity was restricted by the Energy Independence Act’s renewables portfolio standard, enacted in 2006 as Initiative 937.

The EIA requires 15 percent of a qualifying ­utility’s load be met with combinations of eligible ­renewable energy and renewable-energy credits by 2020 and beyond.

Under I-937, the only eligible hydro was recent incremental generation from efficiency upgrades at dams owned by one of 18 qualifying (“large”) utilities, along with hydrokinetic projects and in-state hydro in canal and pipes.

Under the new clean-energy act, incremental ­federal hydro is deemed eligible for ongoing EIA requirements beginning in 2020, a long-sought goal of public ­utilities in the state served by generation marketed by the ­Bonneville Power Administration.

In addition to the expanded use of hydro, the new law explicitly recognizes hydropower variability by ­instituting four-year compliance periods for utilities to meet the carbon-neutral mandate, and in requiring four-year clean energy implementation plans from utilities every four years.