Marys Lake
Larimer County, Colorado · EIA plant ID 517 · Operator: U S Bureau of Reclamation
Nameplate8MWSummer 9 MW
Generators1in service
Net generation36GWh12 mo to Dec 2025
Capacity factor45%hydro units, summer MW
Heat rate—thermal plants only
First online1951
Monthly net generation
EIA-923, all units at the plant. Net of station use; storage can go negative.
FinalPreliminary
Capacity factor by year
Net MWh ÷ (summer MW × hours), hydro units. Each year uses that year's EIA-860 ratings; the hollow dot is the latest 12 months.
Heat rate by year
Electric fuel MMBtu × 1000 ÷ net MWh (Btu/kWh, HHV), fossil units only; CT + CA counted as one combined-cycle block.
Heat rate applies to fuel-burning (thermal) units only.
Annual data table
| Year | Net GWh | Capacity factor | Heat rate (Btu/kWh) |
|---|---|---|---|
| 2001 | 43.6 | 53.6% | — |
| 2002 | 39.4 | 48.3% | — |
| 2003 | 16.7 | 20.5% | — |
| 2004 | 30.7 | 37.6% | — |
| 2005 | 16.3 | 20.0% | — |
| 2006 | 38.2 | 46.9% | — |
| 2007 | 47.1 | 57.8% | — |
| 2008 | 48.2 | 59.0% | — |
| 2009 | 41.3 | 50.7% | — |
| 2010 | 34.1 | 41.8% | — |
| 2011 | 44 | 54.0% | — |
| 2012 | 50 | 61.2% | — |
| 2013 | 27.8 | 34.1% | — |
| 2014 | 35.2 | 43.2% | — |
| 2015 | 19 | 23.3% | — |
| 2016 | 36.8 | 45.0% | — |
| 2017 | 31.1 | 38.2% | — |
| 2018 | 44 | 54.1% | — |
| 2019 | 46.3 | 56.8% | — |
| 2020 | 33.9 | 41.5% | — |
| 2021 | 42.1 | 51.7% | — |
| 2022 | 22.7 | 27.9% | — |
| 2023 | 0 | 0.0% | — |
| 2024 | 4.5 | 5.6% | — |
| 2025 | 36.5 | 44.8% | — |
Generators
EIA-860 (annual) with EIA-860M updates through Sep 2026. EIA-923 reports generation by plant, prime mover and fuel, not by unit, so unit-level output isn't shown.
| Gen ID | Technology | Prime mover | Nameplate MW | Summer MW | Online | Status | Planned retirement | OEM / model |
|---|---|---|---|---|---|---|---|---|
| 1 | Conventional Hydroelectric | HY | 8.1 | 9.3 | May 1951 | Operating | — | coming soon |
Owner / operator
Operator: U S Bureau of Reclamation. Ownership shares by in-service nameplate MW (EIA-860 Schedule 4; units not listed there are wholly owned by the operator).
| U S Bureau of Reclamation | 100.0% | 8 MW |
Nearby plants
Within 80 km.
| Estes | 45 MW | 4.2 km |
| Pole Hill | 38 MW | 17.9 km |
| Flatiron | 95 MW | 25.4 km |
| Big Thompson | 5 MW | 27.7 km |
| Carter Hydro | 3 MW | 27.7 km |
| Granby Hydro | 1 MW | 35.9 km |