Hydro · Analysis

The aqueduct makes power on the way down

LADWP runs century-old hydro plants along the Los Angeles Aqueduct's drop from the Eastern Sierra. It is small, firm, renewable power that the state's rules barely count.

BY THE RENEWABLE ENERGY LA EDITORS · FILED OCTOBER 15, 2026 · 6 MIN READ ·

How falling water turns a turbine

A hydroelectric plant is simple in outline: water drops through a pipe, pushes a turbine, and the turbine spins a generator. What matters is the drop, called head (the vertical distance the water falls), and the flow, how much water moves per second. The aqueduct was engineered to fall steadily from the Eastern Sierra down to Los Angeles, so LADWP placed generating stations where the drop is steepest.

Best known are the San Francisquito power plants above Santa Clarita, which have run since roughly the late 1910s, with more stations strung north up the aqueduct toward the Owens Valley. Because the water is already flowing to supply the city, the power is close to a free byproduct. It is firm in the sense that it runs day and night as long as water moves, unlike rooftop solar across the basin that stops at sundown.

The honest math: small, firm, weather-bound

Add up the aqueduct stations and you get something on the order of a hundred megawatts of capacity, per LADWP's own descriptions, with individual plants in the range of tens of megawatts each. For scale, that is a small fraction of the city's peak demand on a hot afternoon, which runs into the thousands of megawatts. This is not a pillar of the grid. It is a steady, modest contributor that has been quietly doing its job for about a century.

Output is not steady year to year, though. In a deep snow year the Eastern Sierra sends more water down the aqueduct and the turbines earn their keep; in a dry year, or a year when more water is held back for Owens Lake dust control and Mono Basin restoration, generation falls. The honest answer to the question of how much power the aqueduct makes is that it depends on the snowpack and on the water rules, and both of those move.

Why it barely counts as renewable

California's main clean-energy rule, the Renewables Portfolio Standard (the state law requiring utilities to buy a rising share of renewable power), has a quirk for hydropower. Small hydro plants, those rated at roughly 30 megawatts or less, can qualify as eligible renewable, while larger dams generally do not. So some aqueduct stations may count toward the state target even as the much bigger imported hydro from the Colorado River and the Pacific Northwest does not.

That line is the reason a power content label, the yearly breakdown of where your electricity came from, can show 'eligible renewable' and 'large hydroelectric' as separate rows. It is a bookkeeping choice, not a statement about physics. The water falling above Santa Clarita is as renewable as any flow of water gets; whether a given plant lands in the renewable column depends mostly on its size and on how the state and LADWP file the numbers.

Worth watching this month

1. LADWP's next power content label, usually posted once a year, which is where the aqueduct's share actually shows up (routine).

2. The Eastern Sierra snowpack readings this winter from state water surveys, since a wet year raises aqueduct generation and a dry one lowers it (this one matters).

3. Any LADWP power-supply or resource filing that breaks out small hydro, worth a look for plant-by-plant numbers (routine).

4. State decisions on Owens Lake dust control and Mono Basin water, which quietly set how much water, and therefore how much power, moves down the aqueduct (slow, but it matters).

5. CAISO's daily supply mix on a hot October afternoon, a reminder of how small firm hydro is against total demand (routine).

Where this dispatch reads

LADWP: Los Angeles Aqueduct, www.ladwp.com, The utility's own pages on the aqueduct and the hydroelectric stations along its drop.
LADWP: Power Content Label, www.ladwp.com, The yearly breakdown of where LADWP's electricity comes from, where small hydro appears.
California Energy Commission: California electricity data, www.energy.ca.gov/data-reports/energy-almanac/california-electricity-data, State hydropower and generation figures you can check against the utility's claims.
California Public Utilities Commission: Renewables Portfolio Standard, www.cpuc.ca.gov/rps, The rule itself, including why small hydro can count as renewable and large hydro usually cannot.
California ISO: Today's Outlook, www.caiso.com/todays-outlook, The grid operator's live supply mix, useful for scale against total demand.

Questions readers have asked

Is the power from the aqueduct really renewable?

The energy comes from falling water, so physically yes. Whether it counts toward California's renewable target depends on each plant's size, since generally only small hydro of roughly 30 megawatts or less qualifies.

Does this lower my bill?

Only indirectly. It is a small, low-cost source among many, so no single ratepayer can trace a line item to it, but cheap firm power helps hold overall costs down.

What happens in a drought?

Less water down the aqueduct means less generation. In dry years, or when more water is set aside for Owens Lake and Mono Basin, the plants produce less.

How old are these plants?

The best known, above Santa Clarita, have run since roughly the late 1910s. Several others date to the early and mid twentieth century.

Where can I check the numbers myself?

Start with LADWP's power content label and the California Energy Commission's electricity data. Both are public and updated regularly.