Otter Creek Watershed Meeting January 19, 2008

Mike DreischmeierAgricultural EngineerNatural 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-watershed Area(Square

Miles)

100-Year RunoffVolume

(Acre-Feet)

100-Year Peak

Discharge (cfs)

SandmeierBaxter’s Hollow

NortheastUpper Otter Creek

Honey Creek

2.34.75.24.02.1

272.3525.7711.1563.4310.7

9691923192616561336

Table 3: 100-Year Runoff Volume and Peak Discharge Versus Key Land use Components for the Northern Otter Creek Sub-watersheds

Sub-watershed 100-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 HollowSandmeierNortheast

Upper Otter CreekHoney Creek

2.0962.1752.5442.6312.802

409.0412.8367.4412.4642.6

91.482.954.451.134.6

3.42.6

11.019.426.0

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

Otter CreekStone’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 C Stone’s Pocket Road

Total

2-Year5-Year

10-Year25-Year50-Year

100-Year

526468808398

3385

125156183225

85149193236266323

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 DriveUpstream Side of Highway PFUpstream Side of River Road

829.99775.05745.54

830.74775.25745.76

0.750.200.22

Figure 5: Location Map

Highway C Yanke 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 Creek 100-Year Water Surface Elevation (Feet)

With BAAP

Sub-areas(existing)

BAAP Sub-areas

Removed

Reduction in Elevation

At the Upstream Side of Highway CAt the Upstream Side of Yanke DriveAt the Upstream Side of Highway PFAt the Upstream Side of River Road

834.54829.99775.05745.54

834.41829.64774.95745.45

0.130.350.100.09

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’sHollow

North-east

Upper

Otter

HoneyCreek

S. Stone’sPocket

All Sub-watersheds

Highway CYanke DriveHighway PFRiver Road

0.020.010.010.00

0.000.010.010.00

0.120.300.080.07

0.100.260.070.06

0.060.160.040.04

0.000.080.030.02

0.270.880.220.23

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 Creek 100-Year Water Surface Elevation (Feet)

With Channel Obstructions

Without ChannelObstructions

Reduction inElevation

Immediately Upstream of Yanke DriveImmediately Downstream of Yanke DriveImmediately Upstream of Keitel RoadImmediately Downstream of Keitel RoadImmediately Upstream of Prairie RoadImmediately Downstream of Prairie RoadImmediately Upstream of Co Hwy PFImmediately Downstream of Co. Hwy PFImmediately Upstream of Otter Creek RoadImmediately Downstream of Otter Creek RoadImmediately Upstream of River RoadImmediately Downstream of River Road

829.99827.62811.80811.14791.91790.30775.00773.11760.63759.73745.52742.97

829.91827.28811.77811.07791.93790.27775.00773.08760.60759.64745.52742.91

0.080.340.030.07

- 0.020.030.000.030.030.090.000.06

Table 15: Otter Creek 5-Year Water Surface Elevations for the Condition With and Without the Channel Obstructions

Location on Otter Creek 5-Year Water Surface Elevation (Feet)

WithChannelObstructions

Without ChannelObstructions

Reduction inElevation

Immediately Upstream of Yanke DriveImmediately Downstream of Yanke DriveImmediately Upstream of Keitel RoadImmediately Downstream of Keitel RoadImmediately Upstream of Prairie RoadImmediately Downstream of Prairie RoadImmediately Upstream of Co Hwy PFImmediately Downstream of Co. Hwy PFImmediately Upstream of Otter Creek RoadImmediately Downstream of Otter Creek RoadImmediately Upstream of River RoadImmediately Downstream of River Road

823.40823.29810.23809.33790.69788.49774.06771.51758.85757.27744.42741.20

822.94822.81810.18809.24790.68788.47774.07771.51758.83757.18744.42741.16

0.460.480.050.090.010.02

- 0.010.000.020.090.000.04

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)

WithoutConcreteLined Outlet

With ConcreteLined Outlet

Reduction in

Elevation

Immediately Upstream of River RoadImmediately Downstream of River Road

Approximately 275’ Downstream of River RoadApproximately 875’ Downstream of River RoadApproximately 975’ Downstream of River Road

Approximately 1975’ Downstream of River RoadApproximately 2975’ Downstream of River RoadApproximately 3275’ Downstream of River Road

(Wisconsin River 10-Year Floodplain)

745.54743.51741.73739.92739.75738.47737.32737.00

745.54743.51741.62739.45739.14738.04737.16737.00

0.000.000.110.470.610.430.160.00

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 CreekLocationJust UpstreamOf the Given Road

Reduction in the Otter Creek100-Year Water Surface Elevation for the Given Alternative Versus for Existing Conditions (Feet)

Without HwyC and Stone’sPocket Storage

BAAPSub-areasRemoved

With BAAPDetentionBasins

With AllProposedDry Dams

TreeObstructionsRemoved

WithConcreteLinedChannel

Highway CYanke DriveHighway PFRiver Road

0.30-0.75-0.20-0.22

0.130.350.100.09

0.020.030.060.02

0.270.880.220.23

N/A0.100.00-0.01

N/A0.000.000.00

Questions?

Now What?