This has been a lively topic on some of the paddling forums I frequent. One particular area/ecosystem that has caught my attention is that of the BNWR which has had tremendous increase in user days over the last few decades. As a resident user of the river who was active in lobbying against the river being damed by the Corps Of Engineers, which resulted in it being declared a National Wild River in 1972, I have a personal interest in the river.
Of late, high visitation rates have resulted in "TP blooms" in many areas of the river banks. Constant testing shows that coliform bacteria counts remain reasonably low, but still it is a concern. In recent years, park visitation has averaged more than 800,000 visitors a year, 70% of that in the upper section of the 150 mile long river.
One of the state's most promanent paddling advocacy group is having serious discussions about beginning to use rocket boxes such as are now required on many high use Western rivers. Before it is required by legislation. Their suggestions and concerns are directed to extended river tripping by groups of up to 20 people at a time.
Generally speaking, the soil and climate there is conducive to the bacteria that decompose waste, much different than the Western rivers mentioned. The "TP blooms" are more of an eyesore than anything, but they do point to a large number of less than conciencious river users. Distance from water sources and proper technique (catholes less than 8" deep, well covered with loose soil) could go a long way toward keeping the place pristine. Packing out used TP in a large freezer ziplock bag for later disposal isn't a huge imposition.