Delaware Run enters the Olentangy River at RM 25.71. It is 6 miles in length and drains 11 square miles in Delaware County and City. The Ohio EPA monitored this tributary in 1999 at two locations: RM 0.2 and 1.2. This is a perennial stream (flows all year long). 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). At some locations along the run, sulfurous groundwater seeps occurred, leaving a whitish precipitate and a rotten egg odor. However, this did not seem to impact the run negatively (Ohio EPA, 1999).