Your Watershed column: An account of water quality monitoring in our watershed
January 19, 2019
Over the last three years, the Middle Colorado Watershed Council has been sampling and analyzing water quality in the Rifle Creek watershed. Rifle Creek is one of the major tributaries of the Colorado River along our stretch of the watershed, draining 200 square miles through 61 linear miles of perennial streams and rivers.
The Colorado Department of Public Health and Environment (CDPHE) Nonpoint Source Pollution Control Program keeps a list called the 303(d) List of Impaired Waters, documenting waterways throughout the state that don't meet state standards for water quality. In sampling conducted by the state in 2006-'07, Rifle Creek exceeded the accepted limit of selenium, a metal mostly used in electronic and photocopier components. Consequently, this landed Rifle Creek on the state's 303(d) listing, setting the stage for the Rifle Creek Watershed Assessment, beginning in 2015.
Fortunately, data collected by Middle Colorado Watershed Council's watershed specialist Nate Higginson showed that selenium wasn't actually much of an issue in the Rifle Creek watershed. "That's really what we were looking for when we started out with this analysis, but everything checks out. There are some mines in the Rifle Creek watershed, mostly in East Rifle Creek, but sampling across all 13 sites showed selenium at acceptable levels. In micro-amounts, it's actually a nutrient."
But the study kept going. "It was clear that though selenium wasn't a concern and Rifle Creek was going to be removed from the 303(d) listing, we had some other things to keep an eye on that were a concern." CDPHE keeps another list, the Monitoring & Evaluation List, of bodies of water where there is reason to suspect water quality problems but uncertainty exists regarding one or more factors.
Throughout the three years of sampling, arsenic exceeding the state limit was found in 100 percent of the samples, iron exceeding the limit in 20 percent of the samples, and sulfate in 32 percent. "The arsenic we found seems alarming. The standard set for arsenic in our waterways is known to be stringent, but what we found was well above that standard," Higginson said. One main trend was found throughout all the samples: Concentrations of pollutants were generally higher downstream, with the highest arsenic concentrations found in Rifle Creek as it flows through Centennial Park.
Another pattern? "Well, in Colorado," Higginson said, "natural, geologic sources of arsenic are pretty common." Arsenic and other pollutants can leach into the water from mines and irrigation runoff that comes in contact with local geology and soils, and the sulfate may arise from geothermal activity, even if it doesn't reach the surface. "It's all non-point source pollution, that's for sure. We can't point our finger at any singular cause. Geology, land clearing and road building, irrigation activities all play a role. How much? The system is so complex, and there are so many factors, it's impossible to tell."
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With such ambiguous sources, what can we do? How can we improve water quality, and thus the health of our watershed? "The outcome of this study, aside from recognizing pollutants, is to recommend best management practices for restoring impairments in the watershed, from managing OHV areas to restoring riparian areas. We certainly can't change the geology, so if we want to improve water quality, we need to make changes in how we interact with the land."
Jon Nicolodi writes a monthly column for the Middle Colorado Watershed Council, which works to evaluate, protect and enhance the health of the middle Colorado River watershed through the cooperative effort of watershed stakeholders: anyone standing in the watershed. To learn more about the MCWC, visit http://www.midcowatershed.org. You can also find the Council on Facebook at http://facebook.com/midcowatershed. Documentation of this analysis can be found on the website. The MCWC is currently planning their 5th annual Wild & Scenic Film Festival, showing at the Vaudeville on February 21st and the Ute on February 23rd. Need exposure? Contact Jon at email@example.com to inquire about sponsorship opportunities.
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