Patagonia Lake State Park, State park in Santa Cruz County, United States

Patagonia Lake State Park is a state park on State Route 82, 7 miles south of Patagonia, Arizona. Its 250-acre lake, 2.5 miles long, was created by damming Sonoita Creek and has a marina and campground. The park also contains the 873-acre Sonoita Creek State Natural Area, Arizona's first major state natural area, protecting old-growth Fremont cottonwood and Goodding willow riparian forest.

The lake and facilities were built in 1967 by the Lake Patagonia Recreation Association and then handed over to Arizona State Parks in 1974. This transfer shifted the site from private stewardship to public management.

The park hosts an annual mariachi festival each March, and rangers give bird tours and interpretive programs on request. The Sonoita Creek State Natural Area inside the park was Arizona's first major state natural area, and part of it is old-growth Fremont cottonwood-Goodding willow forest listed by the Old-Growth Forest Network.

The park offers boat rentals at the marina, campsites with electrical hookups, and guided bird-watching walks from November through April. The best time to visit is winter through spring when bird populations are most diverse.

A section of Sonoita Creek runs through the park, supporting over 300 bird species, including many rare and migratory types. This water source makes the spot widely known among birdwatchers and nature enthusiasts from around the world.