Horseshoe Run enters the Olentangy River at RM 29.74. It drains 13 square miles in Delaware County. The Ohio EPA monitored this tributary in 1999 at RM 0.30. The results are listed in the table below. The effect of nearly every stressor within the basin was likely made more acute by significantly diminished stream flow within the entire catchment (EPA pg. 59). As classified by the Palmer Drought Severity Index, severe to extreme drought conditions were indicated for the period between July and October 1999 (Ohio DNR 1999).