Lwiddis wrote:
https://www.blm.gov/sites/blm.gov/files/documents/files/LTVASupplementaryRules.pdf
“16. Dumping. Do not dump sewage, gray water, or garbage on the ground. This includes motor oil and any other waste products. Federal, state, and county sanitation laws and county ordinances specifically prohibit these practices. Sanitary dump station locations are shown in the LTVA brochure. You must have an LTVA permit for dumping within all LTVA campgrounds.”
Now we will see posted “...a ranger said...”

As I read this it only applies to Long-Term Visitor Area's on BLM land.
Looks like all the LTVA are in the desert in CA, NV and NM.
Doesn't apply to any of Utah or any other public land.
I've done my homework on dumping gray water where I camp, both on line and in person with US Forest Service and BLM Rangers.
The only restriction is that they don't want it dumped in or near streams and rivers.