Otter Creek Watershed Meeting January 19, 2008 Mike Dreischmeier Agricultural Engineer Natural Resources Conservation Service

Presentation Outline A. Introduction B. Evaluations Made C. Alternative Scenarios D. Summary

A.Introduction  Why a Hydraulic and Hydrologic Analysis?  How is the modeling done?  Who came up with the alternatives to evaluate?

Why a Hydraulic and Hydrologic Analysis?  This analysis allows us to scientifically study the problem and evaluate the effects of changes to the watershed.  Models the watershed to estimate the amount of runoff and depths of flooding.  Allows changes to be evaluated.

How is the modeling done?  NRCS Engineer used two computer programs NRCS Geo-Hydro and Win TR-20 to do the analysis.  40 sub-areas were delineated in the Otter Creek Watershed.  Each area was evaluated using soils, land use, elevation and stream channel characteristics.

Otter Creek 40 Sub Watersheds

How is the modeling done? (cont.)  Program develops peak discharge values and runoff volumes for various storm frequencies at numerous locations in the watershed.

How is the modeling done? (cont.)  Runoff Volume Total amount of runoff from an area. Measured in acre-feet, inches per acre, cubic feet, gallons.  Peak Discharge Flow rate measured in Cubic Feet per Second (CFS). Also gallons per minute. Volume of water in a given period of time.

Who came up with the alternatives to evaluate?  Otter Creek Landowners provided the alternatives to analyze.  Choices are limited by time constraints to do the analysis and by ability to model.  Major changes were evaluated.

B. Evaluations Made  Runoff from northern sub- watersheds. What factors affect runoff volumes?  Effect of roads at Highway C and Stones Pockets Area

Sandmeier Sub-watershed Baxter’s Hollow Sub-watershed Northeast Sub-watershed Upper Otter Creek Sub-watershed Honey Creek Sub-watershed

Table 2: 100-Year Runoff Volumes and Peak Discharge Values for the Northern Otter Creek Sub-watersheds Sub-watershedArea (Square Miles) 100-Year Runoff Volume (Acre-Feet) 100-Year Peak Discharge (cfs) Sandmeier Baxter’s Hollow Northeast Upper Otter Creek Honey Creek

Table 3: 100-Year Runoff Volume and Peak Discharge Versus Key Land use Components for the Northern Otter Creek Sub-watersheds Sub-watershed100-Year Runoff Volume (Inches per Acre) 100-Year Peak Discharge (cfs per Square Mile) Land use (Percent of Sub-watershed) Deciduous Forest Row Crop Baxter’s Hollow Sandmeier Northeast Upper Otter Creek Honey Creek

Figure 4: Approximate Otter Creek 2-Year and 100-Year flood areas Near Highway C and Stone’s Pocket Road Approximate Area Flooded for: 2-Year flood 100-Year flood Otter Creek Stone’s Pocket Road Highway C

Table 4: Flooded Surface Area Upstream of Highway C and Stone’s Pocket Road Storm Frequency Approximate Area Flooded (Acres) Upstream of Highway CStone’s Pocket Road Total 2-Year 5-Year 10-Year 25-Year 50-Year 100-Year

Table 6: Otter Creek 100-Year Water Surface Elevations for the Conditions with and without the Storage in the Highway C through Stone’s Pocket Area Location on Otter Creek Otter Creek 100-Year Water Surface Elevation (Feet) With Storage (Existing Conditions) Without Storage Increase Upstream Side of Yanke Drive Upstream Side of Highway PF Upstream Side of River Road

Figure 5: Location Map Highway CYanke Drive Highway PF River Road

C. Alternative Evaluated  Five alternatives were evaluated as potential flood reduction methods.

Alternative 1  Re-routing the runoff from the Badger Army Ammunition Plant (BAAP) sub-areas (5,7,13) away from Otter Creek.

Table 8: Otter Creek 100-Year Water Surface Elevations from Highway C to River Road for the Conditions With and Without the BAAP Sub-areas Location on Otter Creek100-Year Water Surface Elevation (Feet) With BAAP Sub-areas (existing) BAAP Sub-areas Removed Reduction in Elevation At the Upstream Side of Highway C At the Upstream Side of Yanke Drive At the Upstream Side of Highway PF At the Upstream Side of River Road

Alternative 2  The modification of existing borrow pits in the Badger Army Ammunition Plant (BAAP) to be used as detention or infiltration basins.

Alternative 3  The construction of multiple “dry dams” on intermittent streams coming off of the bluff to reduce runoff and flooding impacts.  29 locations were picked to run the model.  Used assumption the dams would completely store the 100 year event.

Figure 8: Northeast Potential Dry Dam Locations

Figure 9: Northwest Potential Dry Dam Locations

Table 13: Maximum Potential Reduction in the Otter Creek 100-Year Water Surface Elevation for the Condition With Versus Without the Dry Dams in Place Location on Otter Creek – Just Upstream of the Given Road Maximum Potential Reduction in the Otter Creek 100-Year Water Surface Elevation (Feet) for With the Dry Dams Versus Without the Dry Dam(s) in the Given Sub-watershed Sand- meier Baxter’s Hollow North- east Upper Otter Honey Creek S. Stone’s Pocket All Sub- watersheds Highway C Yanke Drive Highway PF River Road

Alternative 4  The Removal of tree obstructions in the Otter Creek channel between Yanke Drive and River Road

Table 14: Otter Creek 100-Year Water Surface Elevations for the Condition With and Without the Channel Obstructions Location on Otter Creek100-Year Water Surface Elevation (Feet) With Channel Obstructions Without Channel Obstructions Reduction in Elevation Immediately Upstream of Yanke Drive Immediately Downstream of Yanke Drive Immediately Upstream of Keitel Road Immediately Downstream of Keitel Road Immediately Upstream of Prairie Road Immediately Downstream of Prairie Road Immediately Upstream of Co Hwy PF Immediately Downstream of Co. Hwy PF Immediately Upstream of Otter Creek Road Immediately Downstream of Otter Creek Road Immediately Upstream of River Road Immediately Downstream of River Road

Table 15: Otter Creek 5-Year Water Surface Elevations for the Condition With and Without the Channel Obstructions Location on Otter Creek5-Year Water Surface Elevation (Feet) With Channel Obstructions Without Channel Obstructions Reduction in Elevation Immediately Upstream of Yanke Drive Immediately Downstream of Yanke Drive Immediately Upstream of Keitel Road Immediately Downstream of Keitel Road Immediately Upstream of Prairie Road Immediately Downstream of Prairie Road Immediately Upstream of Co Hwy PF Immediately Downstream of Co. Hwy PF Immediately Upstream of Otter Creek Road Immediately Downstream of Otter Creek Road Immediately Upstream of River Road Immediately Downstream of River Road

Alternative 5  The construction of a concrete lined channel at the outlet end of Otter Creek  A 6000’ long rectangular channel 50’ wide by 3’ deep was assumed.  Carries approximately the 2 year discharge.

Table 16: Otter Creek 100-Year Water Surface Elevations for the Conditions With and Without the Concrete Lined Outlet Location on Otter Creek 100-Year Water Surface Elevation (Feet) Without Concrete Lined Outlet With Concrete Lined Outlet Reduction in Elevation Immediately Upstream of River Road Immediately Downstream of River Road Approximately 275’ Downstream of River Road Approximately 875’ Downstream of River Road Approximately 975’ Downstream of River Road Approximately 1975’ Downstream of River Road Approximately 2975’ Downstream of River Road Approximately 3275’ Downstream of River Road (Wisconsin River 10-Year Floodplain)

D. Summary  Table of effects.  Questions???  Now What?

Table 18: Reduction in the Otter Creek 100-Year Water Surface Elevations for Various Alternatives Versus for “Existing Conditions” Otter Creek Location Just Upstream Of the Given Road Reduction in the Otter Creek100-Year Water Surface Elevation for the Given Alternative Versus for Existing Conditions (Feet) Without Hwy C and Stone’s Pocket Storage BAAP Sub-areas Removed With BAAP Detention Basins With All Proposed Dry Dams Tree Obstructions Removed With Concrete Lined Channel Highway C Yanke Drive Highway PF River Road N/A N/A 0.00

Questions?

Now What?