Lake Mendocino

Hydro power plant in California, United States of America. Approximate location 39.1972, -123.1856.

HydroCaliforniaUnited States of America

Lake Mendocino is a 4 MW hydro power plant in California, United States of America. It is operated by City of Ukiah - (CA). Based on reported annual generation of 14 GWh, it can supply roughly 3,942 homes. It ranks #6761 of 9,833 United States of America power plants by installed capacity. Commissioned in 1987, it is around 39 years old — long-established. As a non-combustion source, it has no direct CO₂ emissions from generation. In context, hydro supplies about 5.3% of United States of America's electricity; the national grid averages 384 gCO₂/kWh (43.0% low-carbon) (2025).

4MW installed capacity
14GWh reported / yr
3,942homes powered
1987commissioned (~39 yrs)

Plant data: WRI Global Power Plant Database (CC BY 4.0), id USA0007489.

Reported generation trend

2013: 6 GWh20132014: 3 GWh20142015: 4 GWh20152016: 8 GWh20162017: 10 GWh20172018: 6 GWh20182019: 14 GWh201914 GWh

Annual generation (GWh), WRI Global Power Plant Database (CC BY 4.0).

Owner

Operated by City of Ukiah - (CA).

Local climate & thermal context

This hydro plant converts the energy of falling or flowing water through hydro turbines. It sits in a warm-summer Mediterranean climate (Köppen Csb) — Northern Hemisphere, latitude 39.2°N — which shapes how much energy it can produce and how its output varies through the year.

13.0°Cannual mean temp
1,995heating degree-days (base 18°C)
192cooling degree-days (base 18°C)
606 melevation

Monthly mean temperature

J: 7 °CJF: 8 °CFM: 8 °CMA: 10 °CAM: 14 °CMJ: 17 °CJJ: 20 °CJA: 21 °CAS: 19 °CSO: 15 °CON: 10 °CND: 7 °CD21 °C

Heating degree-days here run 19% below the median power plant in this dataset — a proxy for how much extra energy heated equipment must replace through its surfaces in winter.

Climate heat-demand index: 43/100 — this site sits in the mid third of the power plants we cover by heating degree-days.

In colder climates, uninsulated hot equipment (boilers, turbines, valves, steam lines) loses proportionally more heat to ambient air — exactly the loss Inzonex modular insulation is designed to cut.

Climate normals: WorldClim 2.1 (1970–2000 monthly normals, 10 arc-min, CC BY 4.0); zone: Köppen-Geiger world climate classification (Kottek et al. 2006, 0.5° grid). Degree-days & heat-demand index computed by PowerAtlas — a modelled heat-demand proxy, not a measured site figure.

How it compares & nearby plants

The #995 largest hydro power plant of 1449 in United States of America by capacity.

United States of America has 1449 hydro power plants in this dataset, together about 101,657 MW of capacity.

Nearby power plants

Location

Coordinates 39.1972, -123.1856 from WRI Global Power Plant Database (CC BY 4.0). View on OpenStreetMap.

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