Grid · Analysis

Three gas plants on the coast, and why LADWP can't just switch them off

LADWP runs Scattergood, Haynes, and Harbor on ocean water the state wants it to stop using. The retirement dates keep moving, and the reason is local reliability.

BY THE RENEWABLE ENERGY LA EDITORS · FILED OCTOBER 19, 2026 · 6 MIN READ ·

How the ocean-cooling rule works

Once-through cooling has a plain meaning: a plant draws in seawater, runs it past hot equipment one time, and sends it back warmer. The State Water Resources Control Board adopted a policy around 2010 to phase that practice out, because pulling in all that water also pulls in fish, larvae, and eggs. Every coastal plant that uses the method was handed a compliance date, the year it must stop.

Those dates are not fixed in stone. A state body with a long name, the Statewide Advisory Committee on Cooling Water Intake Structures, reviews grid reliability each year and can recommend pushing a date back if shutting a plant too soon would threaten the lights. For the three LADWP stations, the posted dates run from roughly the middle of this decade into the early 2030s, and they have been adjusted more than once at last public report.

Why the basin still leans on them

Los Angeles sits in a bowl ringed by mountains, and most of its cleanest power, desert solar and wind, arrives over long transmission lines that cross those ridges. When a line trips or demand spikes on a hot afternoon, the grid needs generation inside the basin itself, close to the load, to hold voltage and frequency steady. Scattergood in Playa del Rey, Haynes in Long Beach, and Harbor in Wilmington are three of the few large plants that can still do that job on command today.

Batteries are closing the gap, and LADWP has been adding storage that soaks up midday solar and releases it after sunset. Roughly four hours of battery output, though, does not cover a multi-day heat wave or a long transmission outage the way a gas plant that can run for days still can. That reliability role, not any fondness for gas, is why the deadlines keep getting reviewed.

What is supposed to replace them, and when

LADWP once planned to rebuild the three stations with new gas turbines, then reversed course around 2019 and said it would not, steering instead toward renewables, storage, and demand programs. The federal lab NREL later mapped how the city could reach 100 percent clean power in a study known as LA100, with target years in the rough range of 2035 to 2045 depending on how fast everything gets built.

Replacement now leans on a mix: more battery storage, upgraded transmission to carry desert and out-of-state renewables, and, over the longer term, the possibility of green hydrogen at Scattergood. None of that lands on a single clean date. Expect the coastal units to shrink in how often they run well before they fully close, and expect the closure dates themselves to stay under review.

Worth watching this month

1. Watch the State Water Board's next Statewide Advisory Committee report for any change to the posted compliance dates at Scattergood, Haynes, or Harbor, since that is the document that actually moves these deadlines.

2. LADWP's Board of Water and Power Commissioners agendas are worth scanning for storage and transmission contract items tied to replacing coastal generation, a routine but telling signal of pace.

3. Any new edition of LADWP's long-range clean energy plan is where the retirement and repowering assumptions get rewritten, so check whether one has posted.

4. Summer and early fall grid alerts in the LADWP service area matter, because the hottest days are when these plants actually run and the reliability case is tested.

5. Green hydrogen announcements tied to the Scattergood site would hint at how the utility plans to keep a coastal plant useful without drawing ocean water.

Where this dispatch reads

State Water Resources Control Board, Once-Through Cooling Policy, www.waterboards.ca.gov/water_issues/programs/ocean/cwa316, The state .gov page for the policy that orders coastal plants to stop using ocean water, including the compliance schedule.
State Water Resources Control Board, SACCWIS reviews, www.waterboards.ca.gov/water_issues/programs/ocean/cwa316/saccwis, The annual reliability reviews that recommend whether a plant's compliance date should move; the document that actually changes deadlines.
NREL, LA100 Renewable Energy Study, www.nrel.gov/analysis/los-angeles-100-percent-renewable-study.html, Federal lab (.gov) study mapping how LADWP could reach fully clean power and what replaces gas.
LADWP, Power System and Clean Energy, www.ladwp.com, The city-owned utility's own site, where its generation facts, clean energy plans, and board agendas are posted.
California Energy Commission, www.energy.ca.gov, State energy agency (.gov) tracking power plants and the statewide move off gas.

Questions readers have asked

Are these plants running all the time?

No. For most of the year they sit largely idle and fire up on hot afternoons, during transmission trouble, or when demand peaks. On a mild spring day you could pass all three and find them barely running.

Am I paying for them on my LADWP bill?

In effect, yes. LADWP is city-owned, so the cost of building, running, and eventually replacing these plants sits inside the rates you pay. There is no separate line labeled for a single plant.

Why is ocean cooling such a problem?

Drawing huge volumes of seawater through a plant also sucks in fish, eggs, and larvae, and returns warmer water to the ocean. Ending that harm is the point of the State Water Board's policy.

So when do they actually close?

Honestly, it depends. The posted dates stretch from mid-decade into the early 2030s, but each can be extended if the state decides the basin still needs the plant to keep the lights on. Watch the Water Board reviews, not press releases, for the real dates.