K.C. Alvey treads carefully when she and her dog, Stuart, walk the dappled trail behind their apartment in Folsom, Calif. Since the pandemic, her neighbors have included homeless campers along a brook known as Humbug Creek.

There’s the man who periodically emerges from the brush, yelling in fear and tearing at tree limbs. There’s the hoarder who fled last week with his dog as a cleanup crew again cleared his massive campsite — shopping carts, three beds, throw pillows, art, books, mirrors on trees, rugs, torch fuel. Rogue campfires have been frequent.

Until recently, federal appellate courts limited how far cities could go to clear encampments. But late last month, the Supreme Court ruled that they could remove homeless residents sleeping outdoors, a decision that has already begun to reshape how they deal with homelessness.

Three days after the decision, the Folsom police announced they would start citing recalcitrant illegal campers, though they also would team up with nonprofits to provide more homeless outreach.

Ms. Alvey, 57, a marketing manager, is waiting to see what happens. There have been times when the homeless campers “really creep me out,” she said. But she also wants “to be sure they have somewhere they can go where they feel safe.”