San Juan River E. coli hits lab limit after upstream sewer lagoons flood, DEQ says

River tests

E. coli in the San Juan River has climbed past what the state lab can measure, the Utah Department of Environmental Quality said Friday, even though the worst of the flooding has passed. Every sample from the main river at Swinging Bridge, Sand Island and Mexican Hat came back above 2,419 MPN per 100 milliliters, the top of the lab test's range. ^[1]

Samples taken Wednesday afternoon at Mexican Hat, when the river was running at about 21,000 cubic feet per second, showed the same high levels. South Cottonwood Wash, which flows into the river, measured 435 to 579 MPN, more than double the threshold for safe recreational contact. ^[1]

DEQ said flooding damaged sewer lagoons upstream in Pagosa Springs, Farmington and Montezuma Creek, spilling untreated sewage into the river. The floods also damaged septic systems and stirred up large amounts of mud and debris. Before the latest storms, E. coli in the river had peaked Oct. 26 at about 2,400 MPN. ^[1][2]

The department told people to stay out of the river until further notice. No one should swim, wade or boat in it, and animals should not wade in it or drink from it. ^[1]

Drinking water and wells

Public drinking water systems remain safe, DEQ said, because local municipal supplies do not draw from the San Juan River. Water trucked to affected residents comes from a groundwater well in Mexican Hat that is separate from the river, and hauling is expected to continue for one to two more weeks. Drinking water in Montezuma Creek was scheduled for testing Monday. ^[1]

Owners of private wells that flooded or sit near floodwaters can have them tested. Field technicians collect the samples for free, the lab analysis costs $35, and requests go to the Bluff town manager. Technicians will keep testing water twice a week and post updates every Friday, the department said. ^[1]

Mud stays risky

The highest flood surge moved through Montezuma Creek and Bluff on Wednesday and Thursday, and river levels are starting to stabilize, DEQ said. Soaked riverbanks remain at high risk of collapse, and heavy debris is scattered through the area. ^[1]

Mud and soil left by the floods can stay contaminated for months. The department cited CDC estimates that the pathogens take about two to three months to die off and urged anyone who touches mud in flooded areas to wash their hands thoroughly. ^[1]

Gov. Spencer Cox declared a 30-day state of emergency for San Juan and Washington counties the same day, letting the state send more help to flooded communities and seek federal aid. ^[3]