Future condition and concerns for the planning area portion of the watershed 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.

• Current allowable release rates are not low enough to provide the factor of safety included in the ordinance for all portions of the Thorpe and Bee Camp Creek watersheds. This “factor of safety” is an attempt to offset increases caused by existing development that did not fall under appropriate regulations or are too detailed for modeling (such as the timing aspects of peaks from each of the future individual detention facilities and the potential for that to increase release rates downstream of several detention facilities). A portion of Bee Camp Creek watershed is in Hancock County. Since Hancock County has similar release rates to Hamilton County, there is no factor of safety in that portion of the watershed either so increases in runoff rates could occur from development. The upper end of the Thorpe Creek watershed is in Madison County. This portion of the watershed is not expected to develop in the foreseeable future so the lack of regulations in Madison County should not be a problem in the near future. Sufficient existing modeling is not available to determine the impact of development in the Thor Run watershed on runoff peak rates.
• No control on the 50% annual chance flood developed condition discharge has been or is in the Town or County ordinances. Based on a study of the Williams Creek watershed in Hamilton County, development under the current ordinance allows for substantial increases in the 50% annual chance flood. Not only does the ordinance allow increases in the peak discharge but also in the duration of the flood. The 50% annual chance flood is typically the channel forming discharge for streams. When that flood frequency increases in discharge and duration, additional stream bank erosion typically occurs. Such erosion affects not only the stability of the bank and the safety of anything on the bank but the quality of the water as well.
• The downstream portion of the Thorpe Creek floodplain is bounded by high bluffs so an increase in the BFE would not impact additional structures. However, upstream portions may be affected. Insufficient detail is available to make a determination.  Once the new preliminary FIS maps are finalized, modeling results for Thorpe Creek and Bee Camp Creek can be utilized to determine the potential impacts to structures from increased, should that happen to occur in the future.
• Development will add additional infrastructure which will need repairs or maintenance in order to not adversely impact drainage in the watershed. Maintenance of those portions of the system that are or will be added to the regulated drain or regulated subdivision roles can be accomplished with assessments. Other portions that are under the Town’s jurisdiction can be addressed with stormwater utility funds. The level of funds that will be available may or may not be adequate to cover all of the maintenance required.
• Impact on roads/bridges - no change expected.
• This watershed is considered to be urbanizing with anticipated changes to agricultural land use (estimated decrease from 26% to 5.3%) and increase in commercial (17% to 27%) and residential (44% to 68%) with the completion of the Britton Falls and Southeast Fishers developments. Based on available future land use data, imperviousness is estimated to increase from 30% to 49% which is indicative (typically) of moderate to poor water quality.
• Based on future land use data and increased areas of commercial and residential development, it is anticipated that water quality in some or all water bodies will likely continue to be impacted by elevated nutrient, bacteria, total suspended solids, and some metals loads. Water quality samples collected for this Master Plan (Bee Camp Creek and Olio Road, Thorpe Creek and Cyntheanne Road) indicate already elevated nitrogen levels but low phosphorus levels. E.coli concentrations currently exceed the State standards 86% of the time. Biologically and physically, both sampling sites scored very high. Dramatic changes in land use, as anticipated, may significantly affect water quality.
• Current Stormwater Management Ordinance requires post- construction BMPs to remove 80% Total Suspended Solids (TSS) from stormwater runoff. It is assumed that other pollutants of concern will be captured to some extent with TSS. Elevated E.coli violations, as noted in 303(d) Impaired Streams List for Fall Creek and Geist Reservoir, are not addressed.