All you could find? Quote below is from the DIXIE National Forest website...located in your state...Utah.
“For those with camp trailers, dispose of waste and grey water at dumping stations.”
See:
https://www.fs.usda.gov/wps/portal/fsinternet/cs/detailfull/!ut/p/z1/jZBPC4JAFMQ_jVffyzSs2waBluQh_NNeQmNbDXVl3fTrJ1qHoMy5zeM3A2-AQgy0StqcJyoXVVL0_kxXF_RNdBch2a5xZxxOVuCaOAqiATBeltjoO054DD18A3ROHn-IzM3_Buh0fQR0QKY--NexB8oLkY5zkSpd2hyoZDcmmdQfsj9nStXNRkMNu67TuRC8YPpVlBp-i2SiURB_klCXQRDj3SpajzwBgjMq4g!!/dz/d5/L2dBISEvZ0FBIS9nQSEh/?position=Not%20Yet%20Determined.Html&pname=Dixie%20National%20Forest-%20Camping%20&navtype=BROWSEBYSUBJECT&ss=110407&pnavid=110000000000000&navid=110130000000000&ttype=detailfull&cid=stelprdb5137037