 Again, E. coli is found in all natural bodies of water. It's generally safe to splash around in those areas, but when E. coli levels reach past 126 colony-forming units per 100 milliliters of water, then Townsend says the Corps of Engineers needs to prohibit swimming. So we close the swim beaches because if you get too much of it, it's going to ruin your day, maybe even 48 hours until it's all cleaned up.