After a sewage spill into Furnace Creek Wednesday, county health officials warned area residents to keep away from the water.

They should know by now. Both Furnace Creek and neighboring Marley Creek have been closed to direct contact for more than 20 years because of high bacteria levels - on some occasions more than 10 times the amount deemed a health risk.

County and state officials are unsure of the source of the long term pollution.

Elin Jones, county Health Department spokesman, said bacterial levels can be influenced by a number of things, including water fowl, animal waste, failing septic systems, discharge from...