Colorado Low Cost Spay/Neuter Locations:

State-wide:
Denkai Animal Sanctuary: Northern Colorado 
Spay Colorado

Arapahoe County:
All Cat Clinic - Englewood
Humane Society of The South Platte Valley - Littleton 
Twice Purrfect Feline Rescue - Littleton

Archueleta County:
Humane Society Of Pagosa Springs - Pagosa Spring
Humane Society of the Pikes Peak Region - Colorado Springs

Boulder County:
Humane Society Of Boulder Valley Veterinary Clinic - Boulder
Longmont Humane - Longmont

Chaffee County:
Ark-Valley Humane Society - Buena Vista

Custer County:
Wet Mountain Animal Welfare - Westcliffe (S/N cost assistance)

Denver County:
Downtown Animal Care Center - Denver
Dumb Friends League - Mobile Clinic; Denver
PetAid Colorado: Denver
Planned Pethood Plus - Denver
Max Fund Wellness Center - Denver
Metro Denver CAT - Denver
The Feline Fix - Denver 

Eagle County:
Eagle Valley Humane Society - Eagle

El Paso County:
Hamlett Spay and Neuter - Colorado Springs

Fremont County:
Humane Society of Fremont County - Canon City
JJ's Helping Paws (vouchers) - Freemont County

Garfield County:
Colorado Animal Rescue - Glenwood Springs
Journey Home Animal Care Center - ​Rifle
Rifle Animal Shelter - Rifle 

Jefferson County:
Cat Care Society - Lakewood
SpayToday - Lakewood
Table Lake - Golden

La Plata County:
Dogster's Spay & Neuter Program (D-SNiP) - Durango
La Plata County Humane Society - Durango

Larimer County:
Animal Friends Alliance - Fort Collins

Fort Collins Cat Rescue & Spay and Neuter Clinic - Fort Collins 

Mesa County:
Animal Birth Control Grand - Grand Junction

Montezuma County:
For Pets’ Sake Humane Society - Cortez

Montrose County:
Montrose Animal Protection Agency - Montrose

Morgan County:
Fort Morgan Humane Society - Fort Morgan

Otero County:
Peak View Animal Hospital - Fowler

Pitkin County:
Friends of the Aspen Animal Shelter - Aspen 

Pueblo County:
Southern Colorado Spay and Neuter Clinic - Pueblo

Rio Grande County:
SLV Spay and Neuter Alliance - Monte Vista

Routt County:
Routt County Humane Society - Steamboat Springs

Summit County:
League for Animals and People of the Summit (LAPS) - Frisco 

Weld County:
Humane Society Of Weld County - Evans
Every Creature Count - Fort Lupton
Pets of Northern Colorado - Evans