For Open Camping, download a Facility Use Form. All reservations must be made at least two weeks in advance by completing the Oso Lake Facility Use form and submitting it to the Volunteer Services Department (714/ 546-8558 ext. 128 or 151) with your down payment. The Volunteer Services Department is located in the lower level lobby of the Council Service Center at 1211 E Dyer Rd., Santa Ana, CA 92705.