By The Associated Press

HARTFORD — Connecticut’s nuclear power plant shut down one of two units on Sunday because seawater used to cool down the plant is too warm.

Unit 2 of Millstone Power Station has occasionally shut for maintenance or other issues, but in its 37-year history it has never gone down due to excessively warm water, spokesman Ken Holt said on Monday.

Water from Long Island Sound is used to cool key components of the plant and is discharged back into the sound. The water may not be warmer than 75 degrees and following the hottest July on record has been averaging 1.7 degrees above the limit, the Nuclear Regulatory Commission said.

The federal agency issued an “emergency license amendment” last week, allowing Millstone, a subsidiary of Dominion Resources Inc., to use an average temperature of several readings.