COLUMBIA, S.C. (AP) — Customers of South Carolina Electric & Gas could see their rates temporarily cut by nearly 15 percent, under a compromise plan passed Wednesday by lawmakers after the company spent billions on two failed nuclear plants that never produced power.

The bill passed with enough margin to overcome a promised veto from Gov. Henry McMaster. It could end up doing a lot more than lowering rates for the average South Carolina Electric & Gas customer by about $22 a month for several months.

It could also scuttle a proposed merger by SCE&G's parent company SCANA Corp. with Virginia-based Dominion Energy.

Hours before the House and Senate passed the bill Wednesday, McMaster renewed his promise to veto any bill that does not eliminate the entire 18 percent surcharge that SCE&G passed on to customers over a decade as it paid for planning and construction of the two reactors that never generated a kilowatt of power before being shuttered last summer.

The Senate passed the bill 37-2 and the House passed it 109-4 — well over the two-thirds vote needed to override a veto.

Senate Majority Leader Shane Massey said the proposals aren't just rate cuts. They also push back a deadline for regulators to decide how much of the billions of dollars of debt should be paid by shareholders and ratepayers; create a consumer advocate position to act on behalf of utility customers; give the state's watchdog Office of Regulatory Staff the ability to subpoena in their oversight role; and define terms the Public Service Commission can use to decide what charges were "prudent" or "imprudent" when it sets utility rates permanently in December.

The rate cuts are" probably the fourth or fifth most important thing in the bill," Massey said.

"I would hope the governor would look at all the things in there and consider the consequences of doing that over a temporary rate that is only going to be in effect for six months," the Edgefield Republican said.

The governor thinks there is only one thing that matters in this bill — his promise to get back all the rate hikes passed for the project, spokesman Brian Symmes said.

"He's going to keep that promise because no South Carolinian should be forced to pay another dime for nuclear reactors they will never get," Symmes said in a statement.

Massey said the conference committee settled on the 15 percent cut because it could not prove that SCANA had worries about the project when the other 3 percent of hikes passed before 2011.

Meanwhile, from two states away, Dominion Energy again warned it might pull its offer to buy SCANA Corp. if the rate cuts pass. Dominion has offered rebates of around $1,000 to SCE&G customers, a smaller cut in rates and a promise not to raise rates for three years.

Lawmakers are gambling with money for customers and taxpayers that they may never see again if the merger fails, Dominion President Thomas Farrell II said.

"All of this for a few headlines and a temporary rate reduction that has good odds of being overturned in court. It is a disappointing and short-sighted action that is counter to the best interests of South Carolina and its people," Farrell said in a statement.

Massey said senators can't worry about Dominion. "We have received their last, best final offer four times," he said.

The lawsuit threat comes from SCE&G, which has all but guaranteed it will sue if the proposals pass because the utility thinks only the Public Service Commission and not lawmakers can set electric rates.

The bill does not affect rates paid by state-owned utility Santee Cooper, which owned 45 percent of the plants and has about $8 billion in debt. McMaster has urged the state sell the utility, and the House passed a bill creating a committee to study the move.

Massey said lawmakers want to deal with Santee Cooper next.

One of the two votes against the bills in the Senate was Sen. Brad Hutto. The Orangeburg Democrat reiterated arguments he has made all session, that lawmakers were being too rash and opening the state up to lawsuits that would cost taxpayers money and then lose the rate cuts given to customers.

"They are trying to convince you we need to do something when we really don't need to do anything," Hutto said.

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