AltaGas Ltd. says it has signed deals to sell about $560-million worth of natural gas midstream assets and power-generating assets to two buyers.

Birch Hill Equity Partners Management Inc. has agreed to pay $165-million for a group of smaller-scale gas midstream and power assets in Canada, as well as its commercial and industrial customer portfolio in Canada.

The transaction also includes the 43.7 million shares of Tidewater Midstream and Infrastructure Inc., which AltaGas holds.

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In a second transaction, AltaGas says it will sell its San Joaquin power assets in California to a subsidiary of Avenue Capital for roughly $400-million.

The assets include the Tracy, Hanford and Henrietta plants totalling 523 megawatts of generating capacity.

AltaGas says the proceeds from the sales will be used to repay debt related to its acquisition of Washington-based energy utility company WGL Holdings, Inc., which closed in July.