Using Snapshot Sampling to Characterize an Impaired Water.

The Sauk River in the Upper Mississippi River Basin is listed as a fecal coliform impaired water. The 160 km river flows through areas densely populated with feedlots and dairies; however the river also flows through over a dozen lakes which contain many lake homes with un-maintained septic systems. In an effort to better understand the nature of the river's impairment, “snapshots” of the river are being utilized. A “snapshot” refers to a sampling technique in which the E. coli loading of the river is determined for a given day. During a snapshot, water is collected and processed in a single day from 17 established sites along the Sauk River. Thus far, eight snapshots have been collected between September 2006 and September 2008. The highest levels of E. coli loading shown in the snapshots occur when water temperature and/or flow were greatest. However, many more snapshots must be taken before concrete conclusions can be made regarding impairment.