State environmental approval rulemaking wan't arbitrary and capricious; the standards are set out in a parallel section of the Code dealing with reservoir protection, and the delay of the approval for the challenged section until the central pipeline had attained the necessary approvals was akin to moving a pipeline to avoid a stream -- a temporal rather than spatial accommodation.
As the state's clean water laws flow from the federal laws, state agency's consideration of function and use did not displace federal review.
Explanation that didn't cite the relevant standard sufficed, because it tracked the language of the relevant standard.
On remand, state must explain incongruities in finding and why the department opted for a temporary denial rather than a provisional approval.