Unhealthy levels of bacteria from human or animal waste in the St. Lucie River prompted Martin County Health Department officials to warn people to stay out of the water. Bacteria levels are 1,680 colonies per liter, the EPA standard is 1,040. The high levels could be caused by runoff from heavy rain, a concentration of wildlife on or near the river, from bottom sediment stirred up by recent water releases from Lake Okeechobee or malfunctioning septic systems. Sept. 3 was the first time in two years that bacteria levels were too high. Samples are taken every two weeks from nine Martin County locations, mostly at public beaches, as part of the state’s Healthy Beaches Monitoring Program.