Every year, a few weeks before Halloween, the Uncompahgre River seems to blossom with slimy, bubbling growths in areas of the lowest flow. This substance is green algae, decaying and releasing bubbles that are often trapped by iron deposits. Though the algae appears more prominently and abundantly in this season, it's actually present in the river – even in high flow areas – year round. This fall, the slime may be more noticeable due to more pronounced bubbles caused by the unusually warm temperatures.
While this algae is a typical condition of many river systems and streams, it suffocates macroinvertebrates. According to Uncompahgre Watershed Partnership board member and River Watch volunteer Dudley Case, River Watch experts explained that the zinc in the Uncompahgre River negatively effects both fish and macroinvertebrates, and the slime clogs up areas where they might nest and reproduce.
"Macroinvertebrates are a food source for fish, so the less macroinvertebrates, the less fish. Since the slime is so endemic in the river, reducing the slime safely would be a useful project," said Case.
Observing and reporting on these types of water issues is one of the goals of the Uncompahgre Watershed Partnership (UWP) as we monitor watershed conditions and communicate with stakeholders. We are reviewing our Watershed Plan this winter so we can make updates related to project and study results from recent years. We hope you will contribute your observations and ideas about priorities to the review and update process. Please feel free to contact us anytime with your thoughts, and we will be back in touch with you to collect input in the coming months, too.
Thank you to UWP Project Coordinator Agnieszka Przeszlowska for contributing information and photos for this report.