Mccoy Flat dam
Mccoy Flat
Mccoy Flat is a privately owned Earth dam located in Susanville, California, along the Susan River. Built in 1891, this dam serves primarily for irrigation and water supply purposes, with a storage capacity of 17,290 acre-feet and a maximum height of 21 feet. The dam has a low hazard potential and was last inspected in September 2020, with a satisfactory condition assessment reported in September 2017.
Managed by the California Department of Water Resources (DWR) under the Safety of Dams program, Mccoy Flat is regulated, permitted, and inspected by the state agency to ensure its safety and compliance with regulations. Situated in Lassen County, this dam plays a crucial role in water management and supply for the surrounding area. Despite its age, Mccoy Flat continues to function effectively, providing essential water resources for agriculture and local communities.
With a beautiful surface area of 1,800 acres and a drainage area of 110 acres, Mccoy Flat is not only a vital infrastructure for water supply but also a scenic spot for water resource and climate enthusiasts to appreciate. The dam's historical significance, coupled with its functional importance, makes it an intriguing site for those interested in the intersection of water management, climate resilience, and infrastructure development in California.
Dam data reference
Condition Assessment
- Satisfactory
- No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
- Fair
- No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action.
- Poor
- A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency.
- Unsatisfactory
- A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
- Not Rated
- The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Hazard Potential Classification
- High
- Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
- Significant
- Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environmental damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
- Low
- Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
- Undetermined
- Dams for which a downstream hazard potential has not been designated or is not provided.
Plan around the weather
Same NOAA / yr.no feed Snoflo's iOS app uses. Watch the precipitation column on the meteogram -- rain on the basin upstream typically lifts inflow 24-72 hours later.
Next 5 days, hour by hour
Temperature line with weather symbols on top, snow + rain accumulation as columns, humidity as a dotted line.
5-day forecast table
Every 3 hours, broken out across temperature, snow, rain, humidity, and wind. Each cell is colour-coded relative to the column min/max.
| Time | Condition | Temp (°F) | Snow (in) | Rain (in) | Humidity (%) | Wind (mps) | Wind dir |
|---|---|---|---|---|---|---|---|
| Loading detailed forecast… | |||||||
15-day temperature & precipitation
Daily temperatures, snow, and rain projected over the next two weeks.
Nearby streamflow gauges
USGS streamgauges around Mccoy Flat -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Hat C Nr Hat Creek Ca | 195 cfs | → |
| Spanish C Ab Blackhawk C At Keddie Ca | 128 cfs | → |
| Spanish C A Quincy Ca | 61 cfs | → |
| Pit R Bl Pit No 1 Ph Nr Fall River Mills Ca | 1,220 cfs | → |
| Burney C A Burney Falls Nr Burney Ca | 168 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Mccoy Flat.
Boat launches
Campgrounds
Fishing spots
Paddle runs
- Susan River
- 1 Mile West Of Devil's Corral To To Susanville
- Willow Creek
- Within Tunnison Wsa To Within Tunnison Wsa
- Pond In Sec 35, T26n, R9e To Confluence With Spanish Creek
More reservoirs
Track Mccoy Flat in the Snoflo app
Save this dam as a favorite and get the local NOAA / yr.no forecast plus regional flow context wherever you are.
About Mccoy Flat
Where does the data for Mccoy Flat come from?
Structural and regulatory data come from the U.S. Army Corps of Engineers' National Inventory of Dams (NID). Weather forecast comes from NOAA / yr.no -- the same feed Snoflo's iOS app uses.
How often is the report updated?
NID structural data refreshes annually as the Corps publishes updated assessments. The weather forecast refreshes throughout the day.
What does the Low hazard rating mean?
The Corps of Engineers' hazard potential classification grades probable consequences if the dam fails: High = probable loss of human life; Significant = no probable loss of human life but possible economic loss / environmental damage; Low = no probable loss of human life, only minor economic / environmental losses. See the Dam Data Reference card above for the full definitions.
What's "% of normal"?
The current storage value compared to the historical average storage on this calendar day. 100% = right on average; values above 100% mean above-normal storage (wet year); values below mean below-normal (dry year or drought).
Can I get alerts when storage crosses a threshold?
Yes -- alerts are managed in the Snoflo iOS app. Favorite this dam, set a threshold, and you'll get a push the moment conditions cross.
Other water bodies near here
Snoflo-tracked reservoirs and dams within driving distance of Mccoy Flat.