Lewis and Clark County, MT. Reports to the NorthWestern Energy balancing authorityThe organization that balances electricity supply and demand in a reporting area.Definition ↗.
Nameplate capacity, operating generatorsFull nameplate rating of the operating generators, before ownership shares. MW measures rated power; annual output is energy in MWh.Definition ↗
16.3MW
Source & method
Sum of generator nameplate MW with operational status code OP in the inventory year; one row per generator; unscaled by ownership
2024 inventory · reported · derived · valid · final
Net generationEnergy produced over the stated period after the plant’s own use, including signed storage output. Plant output is not allocated to owners or buyers.Definition ↗
134,425MWh
2024
Source & method
Sum of EIA-923 annual net generation over the plant's unique prime-mover x energy-source rows; negative values (pumping, station use) retained
2024 calendar year · reported · derived · valid · final
Net generation MWh / (operating nameplate MW x hours in year); only when every operating generator was operating before the year began and none retired during it
2024 calendar year · reported · derived · valid · final
derived: net_generation_mwh@2024 / (nameplate_mw_op x 8784 h)
Ownership basisHow a generator's owners were established: from EIA-860's ownership schedule (reported), from EIA's rule that a unit absent from a complete schedule is wholly owned by its operator (derived), or unknown.Definition ↗
OwnerAn organization with a reported share of a generator. Owned MW applies that share to operating nameplate capacity; it does not establish who buys the output.Definition ↗Investor-owned utilityNorthWestern Energy ↗
16.3MW owned
Operating nameplate MW x ownership fraction, once per generator; reported schedule or EIA-860 schedule-4 default. Ownership source & rules ↗
Generators at this plant
Unscaled nameplateA generator’s rated maximum power, in MW. Capacity is a rating, not how much electricity it produced.Definition ↗
12 generators, including non-operating units where reported. Status is the inventory-year status.
Generator
Technology / statusWhether a generator or project is operating, planned, on standby or retired, as its source reports it.Definition ↗
NameplateA generator’s rated maximum power, in MW. Capacity is a rating, not how much electricity it produced.Definition ↗ · MW
Ownership basisHow a generator's owners were established: from EIA-860's ownership schedule (reported), from EIA's rule that a unit absent from a complete schedule is wholly owned by its operator (derived), or unknown.Definition ↗
Ownership not established: proposed unit, missing ownership code, unknown operator, or incomplete schedule
Dam and river
Reviewed identity · 2026-09-21
Hauser DamNational Inventory of Dams MT00560· Hydropower is a reported purpose in the NID and GRanDv1.3. Associated power plant is included in the EHA.
EHA 2026 EIA_PtID 2185 = EIA plant; state MT; EHA point 0.14 km from EIA point; names share a token; HILARRI v4 links EHA id to NID MT00560 (Hauser Dam, Missouri River), NID point 0.12 km from EIA point; NID purposes: Hydroelectric;Recreation;Flood Risk Reduction. These rows identify the same structures across inventories; they carry no generation, storage or flow figures.Link evidence ↗
CO2 filed by EPA-monitored units
2024
This plant has no coal, gas, oil or waste generator, so it has no combustion unit for EPA to monitor and no CEMS data exists. That is not a claim of zero emissions: the atlas reports only what EPA-monitored units filed. Source
Latest inventoryThe newest complete monthly inventory, with dated status and capacity changes beside the annual baseline totals.Definition ↗ · August 2026
Operating
2 of 12 units changed since the baseline inventory: HAU10 entered service (August 2026); HAU6 retired or cancelled (August 2026).Next planned unit expected June 2028 (a forecast).
Operating nameplate capacity, latest inventoryOperating nameplate MW in this monthly inventory. Compare it with the annual baseline; do not add the two inventories together.Definition ↗
16.8MW
· provisional
Source & method
Sum of nameplate MW over generators whose current-valid EIA-860M workbook assertion has status OP; dated by the complete inventory edition; never added to the baseline aggregate
Planned nameplate capacity, latest inventoryNameplate MW proposed or under construction in this monthly inventory, separate from operating MW. Planned dates are forecasts.Definition ↗
7MW
· provisional
Source & method
Sum of nameplate MW over generators whose current-valid EIA-860M workbook assertion is a proposal or construction stage (P, L, T, U, V, OT, TS); a proposal is not a commitment and its date is a forecast
Retired or cancelled nameplate capacity, latest inventory
15.3MW
· provisional
Source & method
Sum of nameplate MW over generators whose current-valid EIA-860M workbook assertion is retired, cancelled or indefinitely postponed (RE, CN, IP); retired is not demolished
Units whose current EIA-860M assertion differs from the baseline inventory year.
Unit
Change
As of
Baseline → latest status
Nameplate · MW
HAU10
entered service
August 2026
U → OP
3.5MW → 3.5MW
HAU6
retired or cancelled
August 2026
OP → RE· retired July 2025
3MW → 3MW
Lifecycle of the units
Each unit's operating span from its reported operating date to its retirement date or to the August 2026 inventory (the vertical line). Dashed spans start at a planned operating date, a forecast; a short bar marks a planned retirement. Standby and out-of-service units are hatched.
Units as a table
Unit lifecycle from EIA-860M, August 2026.
Unit
State
Operating since
Planned
Retired
MW
HAU1
Retired or cancelled
November 1911
—
September 2023
2.8MW
HAU10
Operating
July 2025
—
—
3.5MW
HAU11
Operating
May 2021
—
—
3.5MW
HAU12
Planned
—
December 2029
—
3.5MW
HAU2
Retired or cancelled
November 1911
—
December 2019
3.9MW
HAU3
Operating
November 1911
retire June 2028
—
2.8MW
HAU4
Retired or cancelled
November 1911
—
November 2017
2.8MW
HAU5
Retired or cancelled
November 1911
—
April 2021
2.8MW
HAU6
Retired or cancelled
September 1915
—
July 2025
3MW
HAU7
Operating
May 2019
—
—
3.5MW
HAU8
Operating
November 2022
—
—
3.5MW
HAU9
Planned
—
June 2028
—
3.5MW
Independently dated by EIA-860M; the baseline facts above stay the validated edition. Planned dates are forecasts; retired is not demolished.
Approximate service areasAn approximate utility service area. The boundary cannot identify the supplier for a particular address.Definition ↗ containing the plant’s location. A geographic candidate, not a supply relationship.
Sum of generator nameplate MW with status category proposed (planned, under construction, cancelled and similar codes) as listed in the inventory year; a proposal is not a commitment
2024 inventory · reported · derived · valid · final
Megan M. Johnson, Shih-Chieh Kao and Rocio Uría-Martínez. 2026. Existing Hydropower Assets (EHA) Plant Database, 2026. HydroSource. Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA. DOI: 10.21951/EHA_FY2026/3374497
Only the EHA plant identifier, plant name and water body of reviewed rows are republished, as identity beside the EIA plant; EHA capacity and generation are not loaded and never enter any total. An EHA record without an EIA plant id has no entity here.
Hydropower Infrastructure – LAkes, Reservoirs, and RIvers (HILARRI), Version 4 (2026-05-05; DOI 10.21951/HILARRI/3362570; links EHA 2025 plants to NID dams of 2025-08-18, GRanD v1.3, NHDPlusV2 and HUC12)
Hansen, C. H., Matson, P. G., Bozeman, B. B., Turner, S. W. D. 2026. Hydropower Infrastructure – LAkes, Reservoirs, and RIvers (HILARRI) v4. HydroSource. Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA. DOI: 10.21951/HILARRI/3362570
A crosswalk of identifiers, not attributes: the HILARRI row id and its GRanD, NHDPlusV2 flowline and HUC12 ids are republished for reviewed rows only. HILARRI's own quality flags are kept on each row; a link is not a reservoir volume, a flow or a generation series.
National Inventory of Dams, national export dated 2026-09-11 (dam id, name, river, purposes and coordinates used to verify each HILARRI dam link)
U.S. Army Corps of Engineers, National Inventory of Dams (export of 2026-09-11)
The NID id and dam name identify the structure the plant sits at, as HILARRI links it and the 2026-09-11 export confirms it. NID purposes are recorded on the row as the inventory states them (Grand Coulee's NID record lists no hydroelectric purpose). Dam height, storage and hazard fields are not loaded.
Catalyst Cooperative, PUDL v2026.9.0, derived from U.S. EIA Forms 860/923
Data transformed by PUDL from U.S. EIA forms; selected fields republished; EIA data is public with dated acknowledgment (https://www.eia.gov/about/copyrights_reuse.php)
Catalyst Cooperative, PUDL v2026.9.0, derived from U.S. EIA Forms 860/923
Data transformed by PUDL from U.S. EIA forms; selected fields republished; EIA data is public with dated acknowledgment (https://www.eia.gov/about/copyrights_reuse.php)
Catalyst Cooperative, PUDL v2026.9.0, derived from U.S. EIA Forms 860/923
Data transformed by PUDL from U.S. EIA forms; selected fields republished; EIA data is public with dated acknowledgment (https://www.eia.gov/about/copyrights_reuse.php)
Catalyst Cooperative, PUDL v2026.9.0, derived from U.S. EIA Forms 860/923
Data transformed by PUDL from U.S. EIA forms; selected fields republished; EIA data is public with dated acknowledgment (https://www.eia.gov/about/copyrights_reuse.php)