When I was here in 2014, I saw someone plein air painting, and plein air is featured on the Newport Bay Conservancy website, so I guess it's a common activity here. Very little shade, so bringing extra water is recommended.

Address: 2301 University Dr, Newport Beach, CA 92660
Admission: Free
Acres: 135
Approximate miles of trails: 5
Hours: 7:00am to sunset; interpretive center open Tuesday to Sunday 10:00am to 4:00pm
Trail surface: Natural

Links:
OC Parks
Newport Bay Conservancy
Park map (PDF)