Watershed Description

The William Lehr Ditch-Stony Creek Watershed drains 15,877 acres of land from the Town of Fishers, the City of Noblesville, and Hamilton County into the While River. A small portion (4%) of this watershed is in Fishers planning area. Only 22% of this area is incorporated and within the Town’s corporate limits. William Lehr, a regulated drain, is the only waterway in this watershed that is inside the Town of Fishers planning area.

Land in this watershed remains undeveloped (53%) and in agricultural land use. Approximately 30% of the watershed is in low-medium density single family residential land use developed since 2000.

Existing Conditions and Concerns

Existing condition and concerns were gathered using a variety of data sources. All resources are referenced in Chapter 7 of this Master Plan. Supporting documentation on water quantity data listed below can be found in Appendix 2 and water quality in Appendix 3.

• Detailed floodplain study (Zone AE) has been completed for William Lehr Ditch. This study was based on the modeling done for the Stony Creek Watershed Plan completed for the Hamilton County Surveyors Office in 2005.
• No additional hydrologic or hydraulic studies in this watershed were found that were pertinent to this Master Plan.
• There are no USGS gauging stations that provide data that is directly applicable to the portion of this watershed that is in the Fishers planning area.
• Based on the Stony Creek Watershed Plan, existing condition flow rates in the watershed are lower than the default Town or County release rates for new development. In the Stony Creek Watershed Plan, the post development 11-100 year peak flow discharge was recommended to be limited to 0.04 cfs per acre. The 0-10 year post development release rate was recommended to be limited to 0.01 cfs per acre. It appears that these restrictive release rates have not been made a part of the County ordinance. There are no structures in the floodplain.
• There are no structures in the floodplain.
• The vegetation along William Lehr Ditch is sparse.
• Two (2) small areas of notable wetlands are in this watershed. A 5-acre palustrine emergent temporarily flooded wetland and a 4-acre palustrine forested, broad leaf deciduous, temporarily flooded wetland.
• This watershed is predominantly an undeveloped, agricultural watershed with some low-medium density single family residential land use. Proposed annexation area for the Town of Fishers to be developed in low density single family residential development.
• Based on available land use data, imperviousness is estimated to be 47% which is typically indicative of moderate to poor water quality.
• No water quality samples were collected in 2009 as part of this Master Plan effort.
• Other water quality studies:
• 6 sampling locations for the Stony Creek Bioassessment-2003 are located within the larger William Lehr Ditch-Stony Creek Watershed outside of the planning area. These sampling events indicated elevated levels of E. coli while nutrient levels were below water quality targets. QHEI assessments ranged from severely impaired (27/100) in the William Lehr Ditch to supporting warmwater habitat (greater than 60/100 near the confluence of the White River.
• 2 USGS gages are located outside of the planning area; 1 monitoring real-time flow and the other monitoring groundwater quality.
• IDEM has completed fish tissue sampling in 3 locations outside of the planning area between 1984 and 2006.
• A small stretch of William Lehr Ditch is the only waterway in this watershed that is listed on the State of Indiana 303(d) List of Impaired Streams.
• Based on available land use data for this watershed, it is anticipated that water quality in some or all water bodies is likely impacted by elevated nutrient, bacteria, and total suspended solid loads.
• Dry weather screening conducted by the Town of Fishers identified 0 outfalls.

Exhibit 2-4b
Floodplains, Drainage & Flooding Concerns

Known Drainage Problems or Concerns

No drainage problems or complaints were identified in the William Lehr Ditch-Stony Creek Watershed.