Bison Midstream LLC, a wholly owned subsidiary of Summit Midstream Partners LP (SMLP) will acquire the equity interests of some subsidiaries of Summit Midstream Partners LLC (Summit Investments), SMLP said May 6.

The $255 million dropdown transaction is subject to price adjustments.

Crude oil and produced-water gathering systems and transmission pipelines in the Williston Basin (the Polar & Divide system) are up for acquisition by Bison.

SMLP will have a six-month option to also acquire the Stampede Lateral, an oil transmission project under development in the Williston, for an additional $35 million. This project is being offered by a subsidiary of Summit Investments.

The Polar & Divide acquisition is scheduled to close before May 31.

The Polar & Divide system has more than 295 miles of crude oil and produced-water pipelines running through Williams and Divide counties, N.D. They run from the Missouri River to the Canadian border. Long-term, fee-based gathering agreements with several producers back the system. Anchor customers include Whiting Petroleum Corp. (WLL) and SM Energy Co. (SM).

Polar & Divide began operating in May 2013 and currently handles 80,000 barrels per day (Mbbl/d) of crude oil and produced water. In the first quarter of 2015, Polar & Divide gathered over 48Mbbl/d of oil and water from pad sites, central receipt points and truck unloading stations. This amount is up from about 33,500bbl/d on Dec. 31, 2014.

Currently, the COLT Hub in Epping, N.D., receives oil from Polar & Divide. Produced water is delivered to producer-owned and third-party injection wells across the Williston.

Two development projects are underway to provide Polar & Divide customers with additional oil delivery points—these include an interconnect with Enbridge's North Dakota Pipeline system, which is included in the acquisition, and Stampede, which will interconnect with Global Partners LP's Basin Columbus rail terminal near Columbus, N.D.

The Stampede greenfield development project includes a 46-mile, 10-inch diameter crude oil transmission pipeline, under construction. It has throughput capacity of 50Mbbl/d to Basin Columbus. Stampede is underpinned by a long-term contract with Global, including minimum volume commitments. Stampede is scheduled to be in service in fourth-quarter 2015, and acquired by SMLP the end of July 2015.

SMLP will acquire Polar & Divide on the exercise of the $35.0 million Stampede option and about $75 million of growth capex through the fourth quarter of 2016.

The board of directors at SMLP’s general partner approved the terms of the acquisition. The board’s conflicts committee also approved them.

Evercore Partners was the conflicts committee’s financial adviser.

Akin Gump Strauss Hauer & Feld, LLP was its legal adviser.