Mill dam
Mill
Mill is a privately owned earth dam located in North Codorus Township, York, Pennsylvania, along the Codorus Creek. Built in 1863 for grade stabilization purposes, this structure stands at a height of 18 feet and spans a length of 250 feet, with a storage capacity of 589 acre-feet. The dam is under the regulatory oversight of the Pennsylvania Department of Environmental Protection, with state permitting, inspection, and enforcement in place to ensure its safety and compliance with regulations.
With a high hazard potential but a satisfactory condition assessment, Mill has been regularly inspected, with the most recent inspection conducted in December 2020. The dam has a normal storage capacity of 34 acre-feet and serves a drainage area of 73.4 square miles. Despite being over a century old, the structure has undergone modifications in 2005 to ensure its continued functionality. The dam's location in a picturesque setting along the Codorus Creek adds to its historical significance and importance in the local water resource management system.
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 Mill -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Codorus Creek At Spring Grove | 41 cfs | → |
| Codorus Creek Near York | 200 cfs | → |
| West Conewago Creek At East Berlin | 116 cfs | → |
| Gunpowder Falls At Hoffmanville | 24 cfs | → |
| Codorus Creek At Pleasureville | 208 cfs | → |
| Grave Run Near Beckleysville | 8 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Mill.
Boat launches
- Codorus State Park Mooring Cove
- Codorus State Park Main Launch
- Codorus State Park Hidden Cove
- Marina Area, Codorus State Park
- Codorus State Park Smith Station Road
- Codorus State Park Wonder Cove
Campgrounds
- Camp Conewago - Boy Scouts Of America
- Pine Grove Furnace State Park
- Primitive Campsite #5
- Primitive Campsite #6
- Primitive Campsite #7
- Primitive Campsite #4
Fishing spots
More reservoirs
Track Mill 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 Mill
Where does the data for Mill 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 Mill.