Lots of trails within ASRA, (Auburn State Parks) along the American River. Spend a few days hiking and camping - NOTE, no camp fires, bbqs and in some places no cooking stoves what so ever due to fire danger. NOTE, stay out of the Middle Fork of the American River, they release water from Oxbow daily, the water level rises fast and the water is cold -very cold!
Take plenty of water, even more than you think you need. Bring some form of filtration system, if you're going to draw water from the river.
Lots of warnings but they are important and if following the parks rules, regulations and precautions then you can still enjoy the park.