NOAA approves 5-year plan for Hilcorp Alaska Cook Inlet work

Kristen Nelson

Petroleum News+

Hilcorp Alaska received final approval from the National Oceanic and Atmospheric Administration Feb. 20 governing taking of marine mammals incidental to specific activities in support of oil and gas activities in Cook Inlet. The final rule and letter of authorization are effective Feb. 20, 2026, through Feb. 19, 2031.

NOAA's National Marine Fisheries Service can allow incidental, but not intentional, taking of small numbers of marine mammals if it finds that the taking will have negligible impact on species or stocks. NMFS said no serious injury or mortality is anticipated or authorized.

Hilcorp applied for the authorization Oct. 30, 2024, covering takes incidental to oil and gas exploration, production and decommissioning activities in Cook Inlet, including use of tugs in towing, holding or positioning a jack-up rig; pile driving; and pipeline replacement/installation activities, work which could expose marine mammals in the vicinity to underwater noise. NMFS requested additional information in November 2024 which Hilcorp provided in January 2025, and further information which was requested in January 2025 and provided in February 2025.

NMFS requested comments in the Federal Register in March 2025.

Hilcorp submitted a revised application in March 2025, correcting minor details.

NMFS published a proposed rule in the Federal Register July 24, 2025, with a 30-day public comment period.

Five-year activity plan

The agency said the five-year period includes up to 54 days of tugs towing, holding or position a jack-up rig for production drilling at platforms in middle Cook Inlet and Trading Bay; up to 70 days of pile driving supporting production well development at the Tyonek Platform in middle Cook Inlet; up to six days of tugs towing, holding or positioning a jack-up; up to 18 days of pile driving supporting exploration drilling at two locations in the Middle Ground Shoal unit in middle Cook Inlet and one location between the Anna and Bruce platforms on the northern border of Trading Bay; and up to 22 days of pipeline replacement/installation involving either pipe pulling or anchor handling or a combination, at up to two locations in middle Cook Inlet and/or Trading Bay.

Tugs in support of a jack-up rig in Middle Cook Inlet are planned for varying numbers of days during all five years. Pile driving in support of production well development at the Tyonek platform is planned for all five years. Tugs in support of a jack-up in Trading Bay between the Anna and Bruce platform are planned for 2027. Tugs in support of a jack-up at MGS in Middle Cook Inlet are planned for 2029.

Pipeline replacement/installation at Trading Bay in Middle Cook Inlet is planned for 2027 and 2028.

--KRISTEN NELSON