New Mexico under the New WOTUS rule
As I have written in the past, the new WOTUS rule will have a much bigger impact in the arid west than elsewhere because of the large percentage of streams that are ephemeral or intermittent. The prairie potholes in the midwest are a close second, I think. But let's focus on one state in the arid west, New Mexico.
New Mexico is interesting because it is one of the last three states in the country that is not authorized to run the NPDES program. EPA Region 6 writes all of the permits for that state. It has been estimated that upwards of 96 percent of the water bodies in New Mexico will not meet the test for jurisdiction under the new WOTUS rule. If that estimate is off by a third, it's still a big number.
According to a 2005 EPA report I reviewed, at the time, there were 127 individual NPDES permits in New Mexico, 46 general permittees, 151 CAFOs and 102 pretreatment permits. If most of those permits involve discharges to ephemeral streams, which is extremely common in New Mexico, they likely won't need permits under the new rule, and can discharge what they will. There is no state program to fill the gap, and the state has only six water quality inspectors.
Similarly, in Idaho, the City of Jerome, Idaho (population 11,800) discharges to the J Canal, which is a man-made ditch that would not be considered WOTUS under the new rule. Idaho now has the NPDES program, but will it step in to require Jerome to have a permit for its discharges, which ultimately flow into the Snake River? Idaho law prohibits state environmental laws from being tougher than federal standards.
I'm sure there are many more examples of this problem throughout the arid west, especially in Arizona. It will be interesting to see how the regulators adapt to this major re-shuffling of the law. I suspect New Mexico will challenge the rule and ask for an injunction to protect those permits. Other arid west states, however, have Republican governors, and likely will not file challenges, although enviro groups may step in.