About a decade ago or so volunteers from my church did a cleanup of the Guadalupe River Trail encampments (coordinated with the City of San Jose and not in conflict with the encamped homeless people). They cleared out tons of stuff, ranging from ordinary litter to broken down sofas and mattresses. They had to use 2 or 3 times the number of dumpsters they had originally estimated. The change wasn't long lasting, sadly.
The Austin trail could be cleaned out and eventually be restored, but unless the Sacred Homeless are cleaned out, recovery could not happen.