KEMMERER, Wyo. (AP) — PacifiCorp is closing a coal plant in southwest Wyoming, abandoning plans to convert one of the Kemmerer plant's coal units to natural gas.

The coal unit will close at the end of 2017 as a result of declining electricity demands. A PacifiCorp spokesman says the change is also a result of the costs of installing environmental upgrades to meet federal haze requirements.

Spokesman David Eskelsen said Thursday that he did not immediately know how many employees would be impacted by the closure.

The announcement comes the same day Arch Coal and Peabody Energy announced they were laying off 460 employees at mines in the Powder River Basin.