POPCO (Pet Overpopulation Coalition)
Your best resource for low-cost spay and neuter options, as well as financial assistance options, is POPCO (Pet Overpopulation Coalition.) This non-profit organization can answer your questions, help you locate the spay and neuter clinic nearest you, and connect you with resources. Financial assistance is NOT guaranteed and depends upon grants and money available at the time of your inquiry. POPCO serves both Riverside and San Bernardino counties.
The POPCO phone number is 1-877-44-POPCO (76726)

Low Cost Spay and Neuter Clinics

Riverside County Spay and Neuter Clinic
5950 Wilderness Avenue, Riverside, CA 92504 (Get map)
Clinic Hours: Mon-Thurs 7:40am - 7pm (closed for lunch from 12-1pm)
Vaccine Hours: Tuesday-Thursday 10am-3pm (closed for lunch from 12-1pm)
Vaccine clinic held one Saturday per month.
Spay and Neuter: Appointment required.
(951) 358-7373
(951) 358-7387

The Humane Society of San Bernardino Valley
(909) 882-2934
(909) 886-5026
website

Animal Samaritans
72307 Ramon Road, Thousand Palms 92276
760-343-3477
website

Ramona Humane Society Animal Clinic
500 Humane Way (1 blk. West of State St. on 7th)
San Jacinto 951.654.3110
website

City of Moreno Valley City Animal Clinic
951-413-3780
website

Victor Valley Protective League
Apple Valley
760-247-4640
website

For Financial Assistance

POPCO - Pet Overpopulation Coalition
For Riverside and San Bernardino residents only.
Non-profit group that connects pet owners with various resources for spay/neuter financial assistance.
(877) 44-POPCO, that's 877-447-6726

Actors and Others for Animals
(818) 755-6045

Benevolent Animal Rescue Committee
(909) 389-9552

Pet Assistance
(562) 691-3014

Save A Pet (County of Riverside Only)
(951) 682-4623