Outside in Alameda.

Explore 4 listed public parks, trails, forests, and natural areas in Alameda, California. Compare locations and documented activities, with official sources and notices for planning your visit.

Lake Del Valle State Recreation Area: Lake water

Park-specific information

Lake water

The official visitor page posts a blue-green algae caution advisory. Check the managing agency’s current water-quality information before swimming or boating.

Read the official notice: California State Parks visitor directory ↗Source checked Oct 20, 2026

Bethany Reservoir State Recreation Area: Reservoir water

Park-specific information

Reservoir water

The official page posts a caution that harmful algae may be present. Check the park’s current water-quality advice and posted signs before water contact.