Grethe dam
Grethe
Grethe is a privately owned dam located in Walworth, Wisconsin, along the Bloomfield Creek. Built in 1969 by the USDA NRCS, this Earth-type dam stands at a height of 14 feet and has a length of 238 feet. With a maximum storage capacity of 53 acre-feet and a surface area of 50 acres, Grethe primarily serves recreational purposes.
Despite its low hazard potential and fair condition assessment, Grethe poses a very high risk due to its location and potential impact on the surrounding area in the event of a failure. The dam is regulated by the Wisconsin Department of Natural Resources (WIDNR) and undergoes regular inspections, with the last assessment conducted in October 2020. Emergency action plans have been prepared, although they have not been updated recently.
Grethe is a significant structure in the area, providing both recreational opportunities and potential flood control benefits. Enthusiasts interested in water resource management and climate resilience should keep an eye on the risk management measures and updates related to this dam to ensure its continued safety and functionality 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 Grethe -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| White River At Center Street At Lake Geneva | 0 cfs | → |
| Fox River Near New Munster | 500 cfs | → |
| Jackson Creek At Mound Road Near Elkhorn | 4 cfs | → |
| Nippersink Creek Near Spring Grove | 117 cfs | → |
| Nippersink Creek Above Wonder Lake | 19 cfs | → |
| Piscasaw Creek Near Walworth | 3 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Grethe.
Boat launches
- Geneva Lake -- Wrigley Drive Access (City Of Lake Geneva)
- Pell Lake -- Access
- Geneva Lake -- Hillside Road Access (Town Of Linn)
- Schofield Road Town Of Geneva
- Powers Lake -- Access Nr County Hwy F
- Powers Lake -- Access At End Of 396th Ave
Campgrounds
- Rv Camping @ Big Foot Beach State Park
- Tent Camping @ Big Foot Beach State Park
- Lake Geneva Youth Camp
- North Branch Conservation Area (Cyclists Only)
- Mud Lake West
- Camp Lakota - A Boyscouts Of America Camp
Fishing spots
More reservoirs
Track Grethe 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 Grethe
Where does the data for Grethe 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 Grethe.