Cobble Mountain
Hampden County, Massachusetts · EIA plant ID 1630 · Operator: City of Holyoke Gas and Electric Dept.
Nameplate33MWSummer 33 MW
Generators3in service
Net generation7GWh12 mo to Dec 2025
Capacity factor2%hydro units, summer MW
Heat rate—thermal plants only
First online1930
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 | 30.9 | 11.3% | — |
| 2002 | 11.7 | 4.3% | — |
| 2003 | 25.1 | 9.3% | — |
| 2004 | 21.1 | 7.8% | — |
| 2005 | 29.2 | 10.8% | — |
| 2006 | 50.8 | 18.8% | — |
| 2007 | 22.9 | 8.4% | — |
| 2008 | 25.8 | 9.5% | — |
| 2009 | 24.8 | 8.7% | — |
| 2010 | 18.8 | 6.6% | — |
| 2011 | 34.7 | 12.2% | — |
| 2012 | 14.5 | 5.1% | — |
| 2013 | 21.8 | 7.6% | — |
| 2014 | 19.1 | 6.7% | — |
| 2015 | 18.7 | 6.6% | — |
| 2016 | 11.5 | 4.0% | — |
| 2017 | 10.7 | 3.7% | — |
| 2018 | 29.2 | 10.2% | — |
| 2019 | 21.1 | 7.4% | — |
| 2020 | 12.1 | 4.2% | — |
| 2021 | 20.8 | 7.3% | — |
| 2022 | 7.3 | 2.5% | — |
| 2023 | 10.5 | 3.7% | — |
| 2024 | 7.8 | 2.7% | — |
| 2025 | 7.1 | 2.5% | — |
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 | 13 | 12.9 | Jan 1930 | Operating | — | coming soon |
| 2 | Conventional Hydroelectric | HY | 7 | 6.8 | Jan 1930 | Operating | — | coming soon |
| 3 | Conventional Hydroelectric | HY | 13 | 12.9 | Jan 1930 | Operating | — | coming soon |
Owner / operator
Operator: City of Holyoke Gas and Electric Dept.. Ownership shares by in-service nameplate MW (EIA-860 Schedule 4; units not listed there are wholly owned by the operator).
| Springfield Water & Sewer Comm | 100.0% | 33 MW |
Nearby plants
Within 80 km.
| Russell (MA) | 3 MW | 5.5 km |
| International Paper Woronoco Mill | 3 MW | 6 km |
| Indian River Hydro | 1 MW | 7.8 km |
| Twiss Street Solar | 2 MW | 10.2 km |
| Holiday Hill Community Wind | 5 MW | 10.6 km |
| CED Westfield Solar, LLC | 2 MW | 11.1 km |