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 higher than existing condition release rates along Flatfork Creek so discharges are expected to double in the tributary areas of Flatfork Creek. Hancock County has release rate requirements similar to Hamilton County's with the same 0.3 and 0.1 cfs/Ac release rate limits along with further reduction for areas with existing depression storage. Based on the hydrologic modeling for the Hancock County FIS, the 0.1 and 0.3 cfs/acre release rates are higher than the existing peak discharges so discharges would be expected to increase further as Hancock County develops. In Fall Creek portions of the watershed, insufficient existing data is available to allow conclusions. However, Madison County, which controls the upper part of the watershed, does not presently have a stormwater ordinance and so does not prevent increases in discharge due to development.
• No control on the 50% annual chance flood developed condition discharge has been or is in the Town or County current 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.
• An increase in BFE of 2 feet along Fall Creek appears to only add one structure to that flood risk area along with a few acres of land. Along Flatfork Creek, sufficient available studies currently do not exist to analyze impacts.
• 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.
• Additional flooding of bridges or bridge approaches is expected along Flatfork Creek as development occurs in the watershed. If little development occurs in Madison County, then increases in flood elevations at the bridges is not expected to occur as Hamilton County develops in the watershed.
• This watershed is currently considered to be undeveloped and in 70% agricultural land use with pockets of low density residential. However, based on available future land use data, agricultural land use will be replaced by residential (estimated at 95%) and commercial (estimated at 5%). As a result, imperviousness in this watershed is estimated to increase from 47% to 72% which is indicative (typically) of poor water quality.
• Based on future land use data and transition from predominantly agriculture to residential and some commercial, it is anticipated that water quality in some or all water bodies will become more impacted by elevated nutrient, bacteria, total suspended solids, and some metals loads. As part of this planning effort, water quality samples were collected in this watershed at Flatfork Creek and 101st Street. Nitrogen and E.coli concentrations were already elevated while phosphorus levels were consistently low. Both biological and physical assessments had good scores. These scores will most likely be impacted by traditional development practices.
• 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, are not addressed.