J.T. Hirst Dam dam
J.T. Hirst Dam
J.T. Hirst Dam, also known as Purcellville Dam, is a key water supply structure located in Loudoun, Virginia, along the North Fork Catoctin Creek. Owned by the local government, this earth-type dam stands at a height of 34 feet and stretches 600 feet in length. With a maximum storage capacity of 155 acre-feet and a normal storage of 128 acre-feet, the dam covers a surface area of 8.6 acres and serves the primary purpose of water supply.
Managed by the Department of Conservation and Recreation in Virginia, J.T. Hirst Dam is regulated, permitted, inspected, and enforced by state authorities to ensure its safety and functionality. Despite being classified as having a significant hazard potential, the dam is assessed to be in fair condition as of January 2020. With a regular inspection frequency and emergency action plan preparations in place, the dam plays a crucial role in water resource management within the region. Climate and water resource enthusiasts can appreciate the importance of J.T. Hirst Dam in maintaining water supply infrastructure in Loudoun, Virginia, and its role in ensuring water security for the community.
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 J.T. Hirst Dam -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Shenandoah River At Millville | 705 cfs | → |
| N F Catoctin Creek At Rt 681 Near Waterford | 4 cfs | → |
| Piney Run Near Lovettsville | 3 cfs | → |
| S F Catoctin Creek At Rt 698 Near Waterford | 4 cfs | → |
| N F Goose Creek At Rt 729 Near Lincoln | 9 cfs | → |
| Catoctin Creek At Taylorstown | 17 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near J.T. Hirst Dam.
Boat launches
- Shannondale Springs Road 199, Jefferson County
- River Haven Drive Jefferson County
- Bloomery Road 742, Jefferson County
- Harry Byrd Highway Clarke County
- Armory Canal Trail Harpers Ferry
- Petersville Road Brunswick
Campgrounds
- 4 Mile Campsite
- Huckleberry Hill
- Huckleberry Hill Hiker-Biker Campsite
- Brunswick City Campground
- Leave No Trace
- Locust Grove
Fishing spots
- Potomac River Reservoir
- Chesapeake And Ohio Canal
- Culler Lake
- Hunting Creek Lake
- Blairs Valley Lake
- Little Owens Creek
Paddle runs
- Headwaters Adjacent To Fdt 573 To State Route 622 Bridge
- State Route 675 At Edinburg, Va To State Highway 55 Southeast Of Strasburg, Va
- Bixler Bridge On State Route 675 To Karo Landing, Approximately 6 Miles South Of Town Of Front Royal
- Capon Bridge To Ends Just South Of Largent
- Segment C--Nf Boundary To Confluence With North Fork Shenandoah River
- Segment B--State Route 730 Bridge To Nf Boundary
Track J.T. Hirst 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 J.T. Hirst Dam
Where does the data for J.T. Hirst 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 Significant 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 J.T. Hirst Dam.