Grinding Rock dam
Grinding Rock
Grinding Rock is a vital water resource infrastructure in California, specifically located in Snelling, Tuolumne County. This earth-type dam was completed in 1979 and stands at a height of 55 feet, with a hydraulic height of 50 feet, serving the primary purpose of water supply. With a storage capacity of 330 acre-feet, the dam plays a crucial role in flood risk reduction, irrigation, and water supply for the surrounding area. Managed by a public utility, Grinding Rock is regulated and inspected by the Department of Water Resources, Safety of Dams division, ensuring its continued safe operation for the community.
The dam's low hazard potential and satisfactory condition assessment as of 2017 reflect its robust construction and ongoing maintenance. With an associated drainage area of 0.2 square miles and a surface area of 14 acres, Grinding Rock contributes significantly to the water management efforts in the region. Its location on the Tr Turnback Creek, under the jurisdiction of the state of California, highlights its importance in meeting the water needs of the local population and supporting agricultural activities in the area.
Grinding Rock's history of reliable water supply and its role in mitigating flood risks make it a critical asset for the community. As part of the water infrastructure network in California, this dam stands as a testament to effective water resource management and serves as a reminder of the interconnected relationship between water resources and climate resilience in the region.
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 Grinding Rock -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Big C Ab Whites Gulch Nr Groveland Ca | 1 cfs | → |
| Cherry C Bl Dion R Holm Ph | 1,620 cfs | → |
| Tuolumne R Bl Early Intake Nr Mather Ca | 1,990 cfs | → |
| Cherry C Nr Early Intake Ca | 457 cfs | → |
| Tuolumne R Ab Early Intake Nr Mather Ca | 1,490 cfs | → |
| Cherry C Bl Valley Dam Nr Hetch Hetchy Ca | 144 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Grinding Rock.
Boat launches
- Forest Route 1n10 Tuolumne County
- Merals Pool Put-In
- Glory Hole Road 6503, Angels Camp
- Forest Route 1n04, Groveland
Campgrounds
Fishing spots
Paddle runs
- Clavey River From Cottonwood Road To Confluence With Tuolumne
- Clavey River From 3n01 To Cottonwood Road
- Confluence With Middle Fork Tuolumne River To Confluence With Tuolumne River
- Confluence With North Fork And Middle Fork Stanislaus To Clark Flat
- Sandbar To Confluence With North Fork Stanislaus River
- Clavey River At Confluence Of Bell And Lily Creeks To 3n01
Track Grinding Rock 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 Grinding Rock
Where does the data for Grinding Rock 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 Grinding Rock.