MARSHALLTOWN

Operating

Oil power plant

Capacity: 189 MW
Primary fuel: Oil
County: Marshall County
Operator: INTERSTATE POWER AND LIGHT CO
Status: Operating
Commissioned: 1978
EIA plant ID: 1068
Generators: 3
Net generation (2024): 79 GWh
Capacity factor (2024, EIA nameplate): 4.8%
Data vintage: EIA-860 2024 final; EIA-923 2022-2024 final
Coordinates: 42.0472, -92.8601

MARSHALLTOWN, a 189 MW Oil power plant in Marshall County, Iowa. Operated by INTERSTATE POWER AND LIGHT CO, commissioned 1978.

How MARSHALLTOWN compares

With 189 MW of capacity, MARSHALLTOWN ranks 20th among the 198 operating power plants Bywatts maps in Iowa and is the largest of the 77 operating Oil plants in the state. It accounts for about 20% of Iowa's operating Oil capacity and 1.2% of all operating capacity in the state. Nationally it is the 26th-largest of the 544 operating Oil plants in the database. Commissioned in 1978, it is older than 68% of the 198 operating Iowa plants with a recorded commissioning year. Its operator, INTERSTATE POWER AND LIGHT CO, runs 8 operating plants in Iowa totaling 2,312 MW. It shares Marshall County with 5 other operating plants, including LAUREL WIND FARM and VIENNA WIND FARM.

Under the same EIA plant code, EIA-860 lists 3 generators at the site with 189 MW of nameplate capacity. Net generation was 79 GWh in 2024 (a 4.8% capacity factor).

Grid neighborhood

The closest transmission line found within 10 miles is a 115 kV line, under 0.1 miles away. Another 10 operating power plants totaling 559 MW sit within 25 miles; the largest is FPL ENERGY STORY WIND LLC (150 MW, Wind).

Computed by Bywatts from HIFLD power plant and transmission line records and EIA-860/923 survey data; distances are straight-line. Sources and methodology

Weather peril exposure

MARSHALLTOWN is a 189 MW oil power plant in Marshall County, IA, operated by INTERSTATE POWER AND LIGHT CO, commissioned in 1978. Marshall County carries moderate modeled catastrophe exposure in the FEMA National Risk Index, scoring 2.4 of 5 at the 35th national percentile. Tornado is the leading peril, rated Relatively Moderate by FEMA at the 93rd percentile.

The Bywatts loss layer is calibrated to solar PV hardware, so it is not applied to an oil plant. The ratings below are the FEMA National Risk Index county hazard ratings for this location.

2.4 of 5Modeled catastrophe exposure

ModerateExposure band

TornadoLeading peril

Relatively LowFEMA county risk rating

Marshall County hazard ratings

Peril	FEMA rating	National percentile	Peril score	Events per year
Tornado	Relatively Moderate	93rd	4.7 of 5	0.60
Heat wave	Very Low	90th	4.6 of 5	4.9
Strong wind	Relatively High	70th	3.8 of 5	6.4
Winter weather	Relatively Moderate	69th	3.7 of 5	15.6
Wildfire	Very Low	56th	3.3 of 5	<0.01
Lightning	Relatively Low	52nd	3.1 of 5	43.1
Ice storm	Relatively Low	46th	2.8 of 5	0.56
Hail	Relatively Moderate	42nd	2.7 of 5	6.2
Riverine flooding	Relatively Low	38th	2.5 of 5	2.4
Earthquake	Very Low	15th	1.6 of 5	<0.01
Hurricane	Very Low	4th	1.2 of 5	<0.01

Perils not assessed in Marshall County

These perils carry no usable National Risk Index figure for this county, so they are excluded from the scoring rather than scored zero. A zero would claim the peril was assessed and found benign.

Peril	Why it is not scored
Coastal flooding	FEMA rating is "Not Applicable" for this county

Model hail, wind and flood exposure for Marshall County in the weather risk calculator

Ratings are the FEMA National Risk Index county hazard ratings; the peril score is a Bywatts transform of the FEMA national percentile. Full data sources and the solar vulnerability methodology are in the weather risk calculator.

Modeled estimate for screening and negotiation. Built from FEMA National Risk Index county hazard data and a solar vulnerability layer documented above. Not a quote, a binder, or actuarial advice, and not a substitute for a carrier's own model. Hazard data: FEMA National Risk Index December 2025, synced 2026-07-24. Resolution is county level, not site level.