The journalist and/or newsroom have/has a deep knowledge of the topic, location or community group covered in this article.

Voracious, invasive zebra mussels hopped an upstream ride over the summer and added 100 miles of Colorado River to their fast-growing infestation of state waterways, Parks and Wildlife officials said after a recent multiagency, multicounty sampling.

Previously pegged in the Grand Junction area, the Oct. 29 sampling and subsequent analysis found adult zebra mussels upstream in Glenwood Canyon and all the way up to the Colorado River's junction with the Eagle River at Dotsero, near a private lake treated for zebra mussels in August.

"With these new findings, the Colorado River is now considered infested from the confluence of the Eagle River down to the Colorado-Utah border," Colorado Parks and Wildlife said.

The agency Monday declined to further identify the private lake near Dotsero or the owner of the water body just yards from the confluence of the Eagle and Colorado rivers. The agency had said in its September update, however, that the owner understood the severity of the zebra mussel's spread throughout Colorado and was collaborating with the state on the best treatment plan.

"It's important to note, while the identification and treatment of the body of water was an important step forward for managing zebra mussels on the western slope, we still don't conclusively know how these detections are related" to the discoveries in the sweeping Oct. 29 sampling, Parks and Wildlife spokesperson Rachael Gonzales wrote in email responses to questions. "This is why we will continue our sampling efforts above and below the private body of water."

The agency repeated that during the week of Aug. 25, staff "treated a privately owned body of water in western Eagle County using EarthTec QZ, an EPA-registered copper-based molluscicide. In follow-up surveys conducted during the weeks of Sept. 1 and Sept. 8, staff observed positive initial results, having found dead adult zebra mussels in multiple areas around the body of water. CPW staff will continue to routinely monitor the water to evaluate its effectiveness."

A private water ski and wakeboarding club advertises its facilities at Dotsero as having its own lake and recreation access along a half-mile bank of the Eagle River. Wildlife officials and residents farther west, at the mussel-infested Highline Lake near the Utah border, have noted the difficulties of monitoring zebra mussels at lakes where ski and wake boats frequently come and go from the state park, having picked up water from other lakes and rivers. Zebra mussels thrive in the bilge and ballast of many speed boats, and tiny veligers, or larvae, also cling to propellers, engine shafts and other parts.

Highline Lake was drained by CPW and treated for zebra mussels after the pests were found there, and refilled, but then found again to remain contaminated. Some residents questioned the wisdom of the state allowing the national wakeboarding championships to take place at Highline over the summer. CPW said it was aware of the dangers and noted the championships only required two boats that would be rigorously inspected.

Wakeboarding boats in particular take on water as ballast in order to ride low in the water and create a higher wake for acrobatics. A University of Minnesota study of zebra mussels in the Midwest said the larvae can become so embedded inside that style of boat that it takes a hot water flush or five days of drying to clear them safely.

The same Oct. 29 multiagency sampling of state waters at 200 locations also found the smaller but equally invasive New Zealand mudsnail for the first time in the Roaring Fork River, after previous discoveries in the Colorado, Gunnison and Eagle rivers. The mudsnail may not have the reputation or the eye-popping photographic record of the zebra mussels, which congregate around pipes, pilings and infrastructure in a solid mass, but the invertebrate's spread has its own horror-show qualities.

"New Zealand mudsnails are voracious eaters that reproduce rapidly, eating much of the available food," Gonzales said. "They compete with native invertebrates, including native mollusks, for space and food resources. They may reduce the availability of native invertebrate prey for fish -- particularly mayflies, caddisflies and chironomids. They are able to pass through a fish's digestive system unharmed, leaving the fish malnourished."

The problem, Gonzales added, is "there is no viable method in open water for the control of the New Zealand mudsnail, which are very small snails that reproduce rapidly through asexual cloning," meaning even one rogue mudsnail can start reproducing and multiplying quickly. The state emphasizes educating anglers about inspecting and decontaminating boats and other equipment.