Navigating Uncharted Waters: Assessing Geosmin Occurrence in a Colorado Rocky Mountain Source Water River

摘要

Geosmin is a naturally occurring, organic compound that imparts an earthy odor to water.rnGeosmin is produced by some species of cyanobacteria (blue green algae) andrnactinomycetes (a filamentous bacteria) and is difficult to remove during the treatmentrnprocess. Customers are very sensitive to the odor, with some individuals noticing thernodor at extremely low concentrations, from 4-5 μg/L. While it does not pose a threat tornpublic health, its detectable presence can give rise to customer concerns about the qualityrnthe drinking water.rnThe presence of geosmin in water supply lakes and reservoirs in the U.S., Australia andrnEurope is well documented, although factors leading to outbreaks are often not wellrnunderstood. The presence of geosmin in high quality, cold, turbulent, nutrient-poorrnRocky Mountain headwaters is unexpected based on the reported experiences of others.rnThe Cache la Poudre (Poudre) River originates in Rocky Mountain National Park on therneast side of the Continental Divide and is one of two water sources for the City of FortrnCollins, Colorado, Water Treatment Facility (FCWTF). Routine monitoring for geosminrnin both FCWTF raw waters began in 2003 and has revealed episodes of elevated geosminrnin the City’s Poudre River water supply.rnFor utilities that experience episodes of geosmin in source water supplies, an earlyrnwarning detection and monitoring program for geosmin is a critical tool for protectingrndrinking water quality, minimizing associated treatment costs and maintaining customerrnsatisfaction. An understanding of geosmin occurrence, sources, transport and fate isrnessential before watershed activities can be implemented for its control.rnFollowing a geosmin outbreak in early 2010, the City of Fort Collins Utilities initiated arngeosmin monitoring program on the Mainstem of the Poudre River above the FCWTFrnintake. This paper outlines the FCU monitoring approach, the key findings, and thernfactors that have contributed to the program’s success to date.