 Exhibit 2-5a
Regulated Drains & Regulated Watersheds
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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 Sand Creek and Mud Creek.
- This watershed along with the Headwaters Mud Creek – Mud Creek watershed was the subject of three different studies done for the Hamilton County Surveyors Office. The first study found that the discharges used for the Flood Insurance Study were too low. New discharges were calculated and these re-coordinated, higher values have been used in the January 2010 preliminary Hamilton County FIS mapping. The additional studies evaluated the existing conditions in the watershed as well as looking at potential future problems/concerns.
- One USGS stream gauge monitoring flow and stage level exists on Mud Creek downstream of Fishers. That gauge was in operation from 1958 to 1976.
- Based on the Mud Creek Watershed Plan, existing condition flow rates in portions of the watershed are lower than the default Town or County release rates for new development. It appears that these restrictive release rates have not been made a part of the Town or County ordinances. Proposed development is, as a result, allowed to increase the runoff from any given site in the affected sub watersheds.
- The current Flood Insurance Study models of Mud and Sand Creeks appear to have used outdated or less detailed data and methodologies than are currently available. The result is Base Flood Elevations (BFEs), floodplain delineations, and floodway determinations that inaccurately portray the real flood risks along these streams. A few homes are correctly identified in the floodplain but a majority of them were shown to be above the current Base Flood Elevation.
- There are 3 single family residential structures in the floodplain: Sand Creek (2) and Mud Creek (1). More structures are delineated in the floodplain, but the Mud Creek Watershed Master Plan found data to show all but these 3 were incorrectly mapped in the floodplain based on current BFEs.
- Little to no woods along stream corridor until south of I-69 then slightly more woods until confluence with Mud Creek with is heavily wooded (100-200 feet) on either side.
- Approximately 22 acres of notable palustrine forested, broad leaved deciduous temporarily flooded wetlands located at Olio Road and 146th Street (3 acres) and Cumberland Road and 96th Street (19 acres).
- This watershed is considered to be fully urbanized. Saxony at Exit 10 with 350 acres in Fishers (700 acres total) single/multi-family residential, Clarian Saxony Medical Campus, office buildings and retail shops. Fishers Medical Technology Corridor planned along I-69 at Exit 10. Exit 5 Technology Park is an exclusive combination of technology-based business, company headquarters, and light industry. The entire length of 126th Street is being improved as part of the 126th Street Reconstruction Project
- Based on available land use data, imperviousness is estimated to be 73% which is typically indicative of poor water quality.
- Water quality monitoring conducted at Sand Creek and 146th Street, Sand Creek at 106th Street, and Mud Creek and Cumberland Road for this Master Plan indicates:
- Chemical – Nitrogen concentrations were significantly higher in April, May, and June (with highest readings in June) than all other sampling events at each site. Phosphorus concentrations were below detection limits for most sampling events at Sand Creek at 106th Street and Mud Creek at Cumberland Road E. coli concentrations were also higher in April, May, and June at each of the 3 sampling locations.
- Biological – Both Sand Creek locations received an average PTI score of 24 (excellent) resulting in a shared 5th of 10 sites. The Mud Creek location scored lower with an average PTI of 21 (Good).
- Physical – Sand Creek and 146th St received the lowest overall QHEI score (30/100) due to excessive siltation poor channel morphology. The other 2 sites received moderate scores placing them 5th (65/100) and 7th (57.5/100) of 10 respectively. Low individual metric scores associated with pool/riffle structure, bank erosion, and riparian zones were problematic for each site.
- Other water quality studies:
- Macroinvertebrate sampling and QHEI evaluation was completed at 2 locations within the planning area during the development of the Lower Fall Creek Watershed Management Plan; Sand Creek at Brooks School Rd and Sand Creek at 116th Street QHEI scores were 28 and 50 respectively, while PTI scores were 20.5 and 21 respectively (both Good). These evaluations are comparable to evaluations done as part of this Master Plan.
- 4 locations within the planning area were sampled during the Mud Creek Bioassessment in 2003. Sampling indicated elevated E. coli in base flow especially at the location near Verizon, nutrient levels were below water quality targets, and all sites had QHEI scores less than 60/100 (not supporting warm water fauna) and the site near Verizon scored a 25/100.
- No waterways in this watershed are 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, total suspended solids, and metals loads.
- Dry weather screening conducted by the Town of Fishers identified 83 outfalls (observed dry weather flow at 11 outfalls).
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Exhibit 2-5c
Exhibit 2-5d
