Greenwood Afterbay Dam dam
Greenwood Afterbay Dam
Greenwood Afterbay Dam, located in Gwinn, Michigan, stands as a critical water resource structure along the Middle Branch Escanaba River. Completed in 1973, this concrete dam serves the primary purpose of water supply, with a storage capacity of 1080 acre-feet and a maximum discharge of 1200 cubic feet per second. The dam's significant hazard potential is managed through regular inspections by the Michigan Department of Environment, Great Lakes, and Energy (DEGLE), ensuring its satisfactory condition and safe operation.
The dam's structural height of 41 feet and length of 610 feet contribute to its vital role in regulating water flow and storage in the region. With a spillway width of 50 feet for uncontrolled discharge, the Greenwood Afterbay Dam plays a crucial role in flood control and water management efforts. Despite its moderate risk rating, the dam's operational integrity and adherence to regulatory standards underscore its importance in safeguarding the surrounding communities and ecosystems along the Middle Branch Escanaba River.
As a privately owned facility under state jurisdiction, Greenwood Afterbay Dam exemplifies the collaboration between private entities and government agencies in managing water resources sustainably. With its strategic location and functional design, the dam serves as a key component in the broader water infrastructure network, highlighting the intersection of engineering, environmental stewardship, and regulatory oversight in ensuring water security and climate resilience in Michigan's Marquette County.
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 Greenwood Afterbay Dam -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Greenwood Release Near Greenwood | 25 cfs | → |
| Greenwood Diversion Near Greenwood | 14 cfs | → |
| Middle Branch Escanaba River At Humboldt | 54 cfs | → |
| Schweitzer Creek Near Palmer | 12 cfs | → |
| Middle Branch Escanaba River Nr Princeton | 293 cfs | → |
| Michigamme River Near Crystal Falls | 1,430 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Greenwood Afterbay Dam.
Boat launches
- Greenwood Reservoir Road Ely Township
- County Road Pfj Tilden Township
- County Road Lf Republic Township
- County Road Iaj Michigamme Township
- Sm 5 Champion Township
- County Road Aax Champion Township
Campgrounds
- Private Camp
- Bass Lake State Forest Campground (Marquette)
- North Horseshoe Lake State Forest Campground
- Squaw Lake State Forest Campground
- West Branch State Forest Campground
- Rippling River Resort
Fishing spots
Paddle runs
- East Branch Net River, From Its Source In Sec 8, T47n, R32w To Confluence With Mainstem Net River In Sec 24, T46n, R34w
- West Branch Net River, From Its Source In Sec 35, T48n, R34w To Confluence With Mainstem Net River In Sec 24, T46n, R34w
- Mainstem, Easternforest Boundary In Sec 1, T44n, R35w To City Of Crystal Falls
- Net River Mainstem, Confluence With East/West Branches To Confluence With The Mainstem Paint River
- From Wagner Lake In Sec 13, T49n, R31w To Eastern Boundary Of The Ottawa Nf In Sec 12, T48n, R35@
- West Branch From Source In Sec 26, T46n, R23 W To Junction With County Road 444
Track Greenwood Afterbay 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 Greenwood Afterbay Dam
Where does the data for Greenwood Afterbay 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 Greenwood Afterbay Dam.