Utah officials are increasing monitoring along the Colorado River after an automated water sampler detected zebra mussel DNA near Potash — a warning sign that officials say they are taking seriously, but not yet considering an infestation. The detection comes as Utah continues its aggressive effort to keep invasive mussels from spreading beyond Lake Powell. Bruce Johnson, with the Utah Department of Natural Resources’ Aquatic Invasive Species program, says the positive sample is an indicator that the state needs to take a closer look. … Johnson says the state has designated the Colorado River as infested as far south as the Utah border, with detections around Grand Junction and Loma. Lake Powell, meanwhile, is already infested with quagga mussels.