In formal comments about the proposed Pebble Mine, the U.S. Environmental Protection Agency (EPA) said a draft report on the mine’s environmental impact lacks important information and likely underestimates the risk to water quality and fish habitat in the Bristol Bay watershed.

Alaska Public Media reported that the two primary federal agencies involved in Pebble’s application for a Clean Water Act permit are the EPA and the Army Corps of Engineers. The Corps prepared the draft report looking at what impact the copper and gold mine could have on the environment. The EPA issued comments critical of that report.

While the comments are not favorable for proponents of the mine, it has not stopped worked on the site. Pebble spokesman Mike Heatwole told Alaska Public Media that his company continues to conduct wetlands-mapping of the proposed road corridor and plan to drill a dozen new holes for a groundwater study.

“There’s really nothing in their comments that come as a surprise to us,” Heatwole said. “And really the issue at hand is whether or not the issues highlighted by the EPA have been adequately addressed via the process, and if they have not, we’re confident the Corps will ensure this as they work toward finalizing the EIS for the project.”

The EPA provided pages and pages of recommendations for the Army Corps to improve its final environmental impact statement. The comments were signed by Chris Hladick, the EPA administrator for Region 10, which includes Alaska.

In a second document issued by EPA Region 10, the agency concludes the project “may have substantial and unacceptable adverse impacts on fisheries resources in the project area watersheds, which are aquatic resources of national importance.”

A disagreement between EPA Region 10 and the Corps could be decided by higher-ups in Washington. In the meantime, mine opponents say they hope the EPA’s comments embolden Alaska’s congressional delegation to take a stand against Pebble. They’ve been targeting Sen. Lisa Murkowski. She chairs the Senate Energy and Natural Resources Committee. She also chairs the appropriations subcommittee that decides the EPA’s budget.