Great River Wall (Grw) dam
Great River Wall (Grw)
The Great River Wall (Grw), also known as the Northern Canal Wall, is a federal-owned structure in Lowell, Massachusetts, that serves multiple purposes including hydroelectric power generation, fire protection, flood risk reduction, navigation, and recreation. Completed in 1848, this masonry dam stands at a height of 32 feet and has a hydraulic height of 38 feet, with a total structural height of 36 feet. The dam has a storage capacity of 4,500 acre-feet and covers a surface area of 720 acres, with a drainage area of 3,979 acres.
The Great River Wall is part of a network of 15 associated structures and is regulated by the Federal Energy Regulatory Commission. The dam has a low hazard potential and a high risk assessment rating of 2. The emergency action plan for the dam was last revised in 2015, and while the condition assessment is not available, regular inspections are conducted every three years. The dam features flap and slide gates for water control and does not have a spillway.
Overall, the Great River Wall plays a crucial role in managing water resources in the area, providing important services such as flood control and power generation. Climate and water resource enthusiasts will find this historical structure fascinating for its multi-purpose design and impact on the surrounding environment.
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 Great River Wall (Grw) -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Merrimack River Bl Concord River At Lowell | 11,800 cfs | → |
| Concord R Below R Meadow Brook | 311 cfs | → |
| Shawsheen River Near Wilmington | 21 cfs | → |
| Spicket River Near Methuen | 25 cfs | → |
| Beaver Brook At North Pelham | 35 cfs | → |
| Nashoba Brook Near Acton | 7 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Great River Wall (Grw) .
Boat launches
- Pawtucket Boulevard 936-970, Lowell
- Billerica Street 5-65, Lowell
- Willowdale Avenue 1-53, Dracut
- Flint Pond Road, Tyngsborough
- Musquash Pond Boat Launch
- Farm Road, Billerica
Track Great River Wall (Grw) 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 Great River Wall (Grw)
Where does the data for Great River Wall (Grw) 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 Great River Wall (Grw) .