Big Creek State Park
This state park, eleven miles NW of Des Moines is near Polk city. There is fishing, hiking, hunting, and boating. There is an accessible fishing pier. Travel Iowa says the park is “Accessible to Persons with Disabilities.” Call to be sure just what that includes: 515-984-6473. Here is the DNR’s website and the website from Iowa Parks.
? The website says a “26-mile paved multi-use trail allows bicyclists and pedestrians to travel from the beach south through the Saylorville Lake area all the way to Des Moines.” This sounds likely for accessibility, but you had better call to be sure.