Public comment opens on Prudhoe Bay wastewater permit, July 10 deadline

Hilcorp’s Prudhoe Bay seawater treatment plant keeps the North Slope oilfield’s waterflood system moving, and the state is now asking whether its wastewater limits still fit the job. The plant sits at the end of the West Dock Causeway in Prudhoe Bay and treats and distributes seawater used to maintain formation pressure for enhanced oil recovery, so the permit reaches beyond paperwork and into day-to-day field operations.

The Alaska Department of Environmental Conservation opened public comment June 10 on draft APDES individual permit AK0029840 for Hilcorp North Slope LLC’s Prudhoe Bay Seawater Treatment Plant. Residents, agencies and other stakeholders have until July 10 to review the draft permit, the fact sheet and the public notice before DEC makes a final decision.

The discharge at issue is Outfall 001, described in the draft permit as strained seawater backwash. The permit would authorize that discharge into Stefansson Sound in the Beaufort Sea at latitude 70.416512 and longitude -148.528981. DEC says the permit is being reissued with updated conditions rather than opening a brand-new discharge authorization.

Those conditions matter for both operations and oversight. The draft permit includes a chronic mixing zone for temperature change and pH, and an acute mixing zone for total residual chlorine. For people watching industrial activity on the North Slope, those are the details to examine closely: how much water is being returned to the sea, how the permit treats water quality changes near the outfall, and whether the monitoring requirements are strong enough to show what is happening in Stefansson Sound.

The permit also lands in the middle of a broader North Slope wastewater review. DEC’s wastewater permit page lists AK0029840 alongside another June 10 posting for the Kuparuk Seawater Treatment Plant, a reminder that seawater treatment and discharge rules are part of the region’s larger industrial footprint. Hilcorp’s Alaska materials say the company expanded its North Slope operations in 2020 to become co-owner and operator of Prudhoe Bay, where production began in 1969 and where the field is described as the largest in North America.

Anyone who wants to weigh in can use DEC’s public comments process before July 10. The department’s notice also points to hearing and appeal procedures in the fact sheet, and it lists Amy Wockenfuss as the contact for the permit review at Amy.Wockenfuss@alaska.gov.