Entergy Corp. earnings plummeted to a first-quarter loss of $151.7 million, or 86 cents per share, mainly because federal accounting rules forced the utility to take a $356 million pre-tax charge against a nuclear power plant in Vermont.

Vermont’s state government has moved for an early shut down of the Vermont Yankee plant.

Entergy was required to take a pre-tax impairment charge of $356 million, or $1.26 per share after tax.

Entergy said the charge doesn’t reflect a change in the economic value of the plant, assuming it continues operating through 2032. Entergy said it will continue its efforts to keep the plant in operation.

Without the Vermont Yankee charge, Entergy would have earned $79 million, or 44 cents per share, for the quarter. The utility’s results were affected by warmer than expected temperatures, lower energy prices generated by the company’s nuclear plants, and higher income taxes.

Prior to last week’s announcement, stock analysts surveyed by Thomson-Reuters had forecast first-quarter earnings of $1.14 per share. After the announcement, analysts lowered their forecast to 76 cents per share.

Entergy also lowered its 2012 earnings guidance to a range of $3.55 to $4.35 per share. The forecast includes the Vermont Yankee write-off, higher pension expenses, lower energy prices and the milder temperatures in the first quarter.

Last week, the utility lowered its 2012 per-share earnings guidance to a range of $4.85 to $5.65. Previously, Entergy said it expected 2012 earnings of $5.40 to $6.20 per share.