U.S. Forest Service says at https://www.fs.usda.gov/detail/mnf/news-events?cid=STELPRDB5066205
“One critical thing people can do to minimize their impact on the environment is to properly dispose of both human waste and so called “gray water” from cooking and cleaning. Most people understand the concerns with proper disposal of human waste, but some are unaware of the problems that can occur with careless disposal of gray water. Used dishwashing water contains particles of food, which can create both a nuisance odor and attract flies and therefore disease. Soaps, even those designed specifically for camping, can have a negative effect on plants, soils, groundwater, and streams.L
