Dominion Midstream Partners LP closed the acquisition of a 25.93% ownership interest in Iroquois Gas Transmission System LP, the company said Sept. 29.

Dominion Midstream issued about 8.6 million common units to affiliates of National Grid Plc and New Jersey Resources Corp. to acquire their ownership interests in Iroquois.

About 6.8 million units were issued to National Grid, and about 1.8 million units were issued to New Jersey Resources. Both companies agreed to certain transfer restrictions for the units, including a general one-year lockup period. No public market issuance of units was made in connection with these transactions, the company said.

Iroquois owns and operates a 416-mile, FERC-regulated natural gas transmission pipeline running from the Canada-United States border near Waddington, N.Y., to South Commack, N.Y.

The ownership stake in Iroquois will contribute about $20 million annually in cash flows to Dominion Midstream.

Dominion Midstream will not acquire the 24.72% ownership interest in Iroquois currently held by Dominion Gas Holdings LLC, a wholly owned subsidiary of Dominion Resources.