York Indian Rock Dam dam
York Indian Rock Dam
York Indian Rock Dam, located in York, Pennsylvania, is a Rockfill dam completed in 1942 by the US Army Corps of Engineers for Flood Risk Reduction on Codorus Creek. Standing at 83 feet tall and with a storage capacity of 48,000 acre-feet, the dam plays a crucial role in reducing the risk of flooding to downstream communities. However, despite its risk reduction measures, the dam still poses a high hazard potential, especially during high-volume releases from its spillway during significant storm events. In the event of a breach, downstream communities like York and Grantley could face devastating flooding, with the potential for swift and deep floodwaters overflowing levees and destroying key infrastructure.
To mitigate these risks, the US Army Corps of Engineers actively manages and monitors York Indian Rock Dam. Regular inspections, monitoring, and emergency response exercises are conducted to ensure the dam's integrity and preparedness for potential flood events. The Emergency Action Plan for the dam is regularly updated, and close monitoring of rainfall forecasts helps determine when high water events may occur to provide timely flood warnings to downstream communities. While the dam serves as a crucial flood risk reduction structure, the potential for catastrophic flooding in the event of a breach underscores the importance of ongoing risk management measures and preparedness efforts by the US Army Corps of Engineers to safeguard downstream communities along Codorus Creek.
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 York Indian Rock Dam -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Codorus Creek Near York | 200 cfs | → |
| Codorus Creek At Spring Grove | 41 cfs | → |
| Codorus Creek At Pleasureville | 208 cfs | → |
| West Conewago Creek Near Manchester | 143 cfs | → |
| West Conewago Creek At East Berlin | 116 cfs | → |
| Susquehanna River At Marietta | 27,200 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near York Indian Rock Dam.
Boat launches
- Lake Williams - Lake Under Drawdown
- Lake Redman
- Codorus State Park Mooring Cove
- Codorus State Park Main Launch
- Marina Area, Codorus State Park
- Riverview Park
Campgrounds
- Camp Conewago - Boy Scouts Of America
- Camp Andrews
- Pine Grove Furnace State Park
- Crazy Horse
- Custer
- Cochise
Fishing spots
Track York Indian Rock Dam 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 York Indian Rock Dam
Where does the data for York Indian Rock Dam 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 High 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 York Indian Rock Dam.