South Tani Reservoir
South Tani Reservoir is an earth dam located in Adams County, Colorado, built in 2006. It carries a High hazard potential classification and has a satisfactory condition assessment.
About South Tani Reservoir
The primary purpose of South Tani Reservoir is water supply. The dam stores water for municipal, industrial, or agricultural use, helping ensure a reliable supply for the surrounding area. The dam is owned by City Of Thornton (private). It impounds the South Platte River-os near Thornton.
The dam stands 22 feet tall and stretches 14,200 feet across, creates a reservoir covering 228 acres, and has a maximum storage capacity of 7,530 acre-feet. Completed in 2006, the structure is relatively new.
This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. Its condition is rated satisfactory, indicating no existing or potential dam safety deficiencies are recognized. An emergency action plan is in place for this dam. The most recent inspection on record was 11/02/2022.
Living Downstream
If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The Colorado dam safety program can provide more specific information about emergency planning for this structure.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | Colorado |
| County | Adams |
| Nearest City | Thornton |
| River/Stream | South Platte River-os |
| Coordinates | 39.84402, -104.93949 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 22 ft |
| Dam Height | 22 ft |
| Dam Length | 14,200 ft |
| Year Completed | 2006 (20 years old) |
Storage & Hydraulics
| NID Storage | 7,530 acre-ft |
| Max Storage | 7,530 acre-ft |
| Normal Storage | 6,607 acre-ft |
| Surface Area | 228 acres |
| Max Discharge | 930 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Water Supply |
| Owner | CITY OF THORNTON |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 11/02/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CO02864 |
| Federal ID | CO02864 |
| More Info | State Dam Safety Program |