PPL Montana, the operator of Kerr dam on Flathead lake near Polson, US, wants permission during extreme drought years to keep Flathead lake's summertime level 30.5cm below normal.

The aim is to balance the competing interests of irrigation, flood control, recreation, electric power generation and minimum in-stream flows during extreme low-water years like last summer.

The company’s license currently requires it to release specified minimum flows to protect the lower Flathead river while also maintaining full lake levels in the summer to enhance recreational use of the lake.

FERC has ordered PPL to submit an operating plan for drought periods.