Seattle owns its hydro, and the bills show it

How Seattle's dams keep the power clean

City Light generates most of its own electricity from hydro. The two big pieces are the Skagit River project in the North Cascades (the Gorge, Diablo, and Ross dams) and Boundary Dam on the Pend Oreille River near the Canadian border. Boundary alone is the utility's largest single resource, on the order of 1,000 megawatts of capacity at last public report, and the Skagit dams add roughly several hundred megawatts more.

When its own dams do not cover demand, the utility leans on the Bonneville Power Administration, the federal agency that markets power from the Columbia and Snake river dams and runs much of the region's high-voltage grid. That mix, mostly hydro with Bonneville filling the gaps, is why City Light reports carbon-neutral electricity. It is also why a dry winter matters more to your bill here than a spike in the price of natural gas.

The honest math on your bill

Cheap water power does not mean a flat bill. City Light is a municipal utility, so its rates are set by the Seattle City Council, not by the state's Utilities and Transportation Commission that oversees investor-owned companies like Puget Sound Energy. The Council has approved a run of rate increases in recent years, roughly in the mid-single-digit percent range annually at last public report, to cover aging dams, wildfire preparation, and debt.

Hydro also swings with the snowpack. In a low-water year the utility generates less and sometimes buys replacement power on the open market, which costs more than its own generation. City Light keeps a rate-stabilization account meant to smooth those swings, but a string of dry years can still push the utility back toward the Council asking for relief.

What the fleet still needs

The biggest open question is the Skagit relicensing. City Light's federal license to run the three Skagit dams goes through the Federal Energy Regulatory Commission (FERC), the agency that licenses non-federal hydropower, and that relicensing has been underway for years with fish passage and the concerns of the Upper Skagit and Sauk-Suiattle tribes near the center of it. Expect the process to run past its early schedule, because hydro relicensings routinely do.

New demand is the other pressure. As Seattle electrifies heating and cars, load grows, and the utility has pointed to transmission upgrades and new clean resources (including contracts for wind and solar outside the city) to meet the Clean Energy Transformation Act, the 2019 state law requiring Washington utilities to reach 100 percent clean electricity by 2045. None of that is cheap, and it lands on the same bill you already watched tick up.

Worth watching this month

1. FERC's docket for the Skagit River Hydroelectric Project relicensing, where new filings and study reports post as they arrive, is the one to track if you care about the dams' long-term terms.

2. The Seattle City Council's fall budget and any City Light rate proposal inside it, which sets what you pay next year, is worth a look and is more consequential than routine.

3. Bonneville Power Administration's water supply and generation outlooks heading into winter, an early read on how tight regional hydro will be, are routine but telling.

4. Washington snowpack reports as the Cascade season begins give the cheapest early signal of how much of next year's power comes from City Light's own dams versus the market.

5. City Light's integrated resource planning updates, which spell out the new wind, solar, and transmission the utility says it needs by 2045, are where the build-out plan actually shows up.