Missouri regulators have approved a $172 million increase in electric rates for Ameren Missouri, but the company won't be permitted to recover costs it sought to rebuild the Taum Sauk reservoir.
The Public Service Commission approved the increase Wednesday on a 5-0 vote. It takes effect in August and is expected to raise the average residential bill about $8 a month.
St. Louis-based Ameren Missouri is the state's largest electric utility with about 1.2 million customers, mostly in eastern and central Missouri.
Regulators decided against letting Ameren Missouri add part of the cost for building the new Taum Sauk reservoir into the rate base that is collected from electric customers over time. In December 2005, the original Taum Sauk reservoir collapsed. That sent a billion gallons of water down a southeastern Missouri mountain.