Lake Needwood dam
Lake Needwood
Lake Needwood, also known as Upper Rock Creek Watershed Site 5, is a captivating water resource nestled in Montgomery, Maryland. Managed by the local government, this reservoir serves as a popular recreational spot for residents and visitors alike. Originally designed in 1965 by USDA NRCS and USDA SCS, the dam stands at a height of 65 feet and boasts a storage capacity of 7,023 acre-feet, with a surface area of 74 acres.
With a drainage area of 12.8 square miles and a maximum discharge of 25,652 cubic feet per second, Lake Needwood plays a crucial role in managing water flow and providing flood control for the Rock Creek watershed. Although the dam is classified as having a high hazard potential, its fair condition assessment suggests that it is currently stable. Regular inspections and maintenance ensure the safety and functionality of this earth dam, which has undergone repairs in 2007 to reinforce its foundation.
As one of the key structures in the region's water management system, Lake Needwood offers a serene setting for outdoor activities and wildlife observation. With its uncontrolled spillway and slide gates for outlet control, the reservoir is equipped to handle the demands of both recreation and flood protection. Climate and water resource enthusiasts can appreciate the balance of ecological conservation and human enjoyment that Lake Needwood embodies, making it a valuable asset in Maryland's landscape.
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 Lake Needwood -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Nw Branch Anacostia River Near Colesville | 15 cfs | → |
| Hawlings River Near Sandy Spring | 951 cfs | → |
| Patuxent River Below Brighton Dam Near Brighton | 86 cfs | → |
| Patuxent River Near Unity | 120 cfs | → |
| Cattail Creek Near Glenwood | 183 cfs | → |
| Rock Creek At Sherrill Drive Washington | 82 cfs | → |
About Lake Needwood
Where does the data for Lake Needwood 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 below 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.
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.