The changes announced last month set time limits for reviews, allow Ottawa to hand off assessments to provinces and call for three agencies to do the reviews — down from 40 government departments that can be involved now.
Premier Brad Wall supports the change, but said Wednesday that he's concerned about how it will get done.
"At the official level anyway, they're talking about a negotiation each time there's a project, an assessment of who should do the assessment. It's getting to sound really unnecessarily bureaucratic and kind of defeats the purpose, not completely, but to some extent," he said.
"We just want to make sure that the principle of one project, one assessment manifests in the implementation of it."
Wall said there should be broad agreements in advance on who will do assessments in specific areas. For example, he said, the province could be responsible for assessments on potash mines.
The premier said he raised the issue when Prime Minister Stephen Harper was in Regina last week to meet Prince Charles.
The topic came up again at the western premiers meeting in Edmonton this week. Wall said a letter outlining concerns will be sent to Harper.
Oil, gas and mining interests, as well as some provincial governments, have praised Ottawa for eliminating duplication in environmental assessments and making them more efficient.
Environmental groups and others have criticized the changes.
Scott Vaughan, federal commissioner of the environment and sustainable development, has said Ottawa's new approach means the public will have far less input into natural resource development in Canada.
Organizations including the David Suzuki Foundation, Greenpeace and Equiterre have banded together to oppose what they call a Conservative attack on nature and democracy.