Home / Power plants / Oklahoma / Markham

Markham

Hydro power plant · Mayes County, Oklahoma

Nameplate capacity
128 MW
Rank in Oklahoma
#77
of 147 plants
In service since
1964
May 1964

Details

Primary fuel
Hydro
Technology
Conventional Hydroelectric
Operator
Grand River Dam Authority
County
Mayes County
Generating units
4
Share of state capacity
0.35%
Rank among hydro plants in Oklahoma
#3 of 11
EIA plant code
2980

Generating units

Individual generating units at Markham
UnitTechnologyNameplateSummerOnlineStatus
1Conventional Hydroelectric32 MW32 MW1964Operating
2Conventional Hydroelectric32 MW32 MW1964Operating
3Conventional Hydroelectric32 MW32 MW1964Operating
4Conventional Hydroelectric32 MW32 MW1964Operating

Nameplate is the maximum rated output; summer capacity is what the unit can reliably deliver on a hot day, which is typically lower.

Similarly sized plants in Oklahoma

About this data

From EIA’s inventory of operable generators, May 2026 release. Capacity is nameplate — the maximum rated output of the equipment, not what the plant actually generates over a year, which depends on how often it runs. A 128 MW solar plant and a 128 MW nuclear plant have the same entry here and produce very different amounts of electricity.

“In service since” is the earliest in-service date among the units still listed, so a site rebuilt around newer equipment can read as younger than the site itself. All Oklahoma power plants · What Oklahoma actually generates