State of the River: Part 1

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RBC I Seven years since the first major algae bloom affected the White River, much is still unknown about what exactly causes the blooms, and by extension, how they can be remediated/mitigated in the future. 

The earliest report of significant algae blooms in the river, noted in the HT was in August 2014, when Town of Rangely Trustees discussed filters clogged with algae due to excess algae in the river during July of that same year. Rio Blanco Water Conservancy District Manager Alden Vanden Brink described how the summer 2014 bloom was affecting all parts of the river, stating “Something happened overnight that wasn’t there in 2013 that was there in 2014.” 

Since then, infestations of green filamentous algae have come and gone, thriving in the “prime conditions” of severe drought, high temperatures, and peak flows occurring earlier and earlier every year–all of which set the stage for increased algae growth. These facts about the climate, however, are part of a multi-decade trend that extends well beyond 2014, leading many to question, if not climate alone, what else might be causing the algae blooms?


Based on information from other areas of the state/country with similar algae overgrowth issues, examinations of “research literature,” and a local Colorado Parks and Wildlife study in 2016, multiple potential causes for algae growth in the White River had been identified by the summer of 2017:

Increased nutrients in the river (particularly nitrogen and phosphorus) caused by:

  • soil erosion and/or disruption along the riverbank
  • removal of natural riparian vegetation
  • buildings and septic systems placed too close to streams
  • poorly constructed/maintained septic systems
  • a “large amount” of new septic systems
  • application of fertilizer too close to streams) or at the wrong time of year)
  • Fish feeding byproduct (nitrogen and phosphorus) entering the river

Other potential/related factors have been: 

  • Aerial insecticide spraying (possibly leading to a significant reduction in macroinvertebrates that would feed on the algae)
  • Changes to river hydrology/streamflow including dredging that affect the natural channel
  • Ponds that “heat water and grow algae” then drain into the river

Despite an abundance of community meetings, tedious data collection/analysis from various groups, and much in the way of speculation about the cause of algae blooms in the river, a “smoking gun” has yet to be identified. As it stands, RBC residents will likely not get that level of certainty anytime soon.

Observation and analysis from a diverse array of sources since 2014 have widely agreed that algae blooms are likely a result of multiple compounding factors. In 2017, Colorado Parks and Wildlife water quality specialist Mindi May said, “There’s lots of little sources spread all around. If everybody can do a little bit, maybe we can get it under control.”


General agreement aside, the issue has had its own share of controversy. Since 2014, White River stakeholders have disagreed on plenty, be they environmental experts, state agencies, advocacy groups, landowners or elected officials.

Those involved with the process have debated subjects like:

  • which factors could play the most significant role in algae growth
  • where (and how) to focus investigative resources 
  • study methodology, timeline, scope, etc..
  • enforcement/remediation of any identified man-made algae “sources”

Most disagreements thus far have stemmed from what to do, and how to deal with/prevent algae in the short and long term. On one side there were people who wanted to take deliberate action to remediate/restore river health as soon as possible. Some examples include individuals more closely associated with the White River Alliance, which was formed in 2018 to increase citizen awareness and involvement on river issues. Alliance members have described their intentions relating to algae blooms as “a community based approach in moving forward and promoting improved management practices.”

Alternatively, others praised White River Conservation District’s approach (WRCD) of waiting to take action on algae remediation until more information was available, emphasizing that more data/analysis from a then-proposed USGS study (now ongoing) would be needed before taking any action. 

In a March 31, 2018 Letter to the Editor titled “River recovery needs to begin sooner, rather than later” White River Alliance member Dr. Bob Dorsett criticized the idea that “we don’t know enough” about conditions in the White River to begin remediation work, stating “It is true that we have not yet identified all the particular sources of excess nutrients causing the algae bloom, and careful investigation by USGS is warranted. But we already know plenty, and it is past time to start fixing the problem.” Dr. Dorsett’s letter also lists potential remediation efforts including removal/ modification of ponds along the river, restoring river bank vegetation, removing barriers from the river to “restore the normal channel,” and stopping fish feeding.


During a White River Conservation District (WRCD) Algae Technical Advisory Group (TAG) meeting in March of 2018, 14 agency representatives approved a three-year study to collect scientific data about what’s been causing algae blooms. Hendrickson assured the group that the scope of work being recommended would address “all the possible causes for the algae bloom that have been suggested to date.” In this week’s commissioner meeting, Hendrickson told commissioners they are waiting on the final report. Once that report is available, probably by the end of the year, it will go to the Technical Advisory Group (TAG). Hendrickson stated it will be important to supply “ground truthing” verification of the findings of the USGS report to stakeholders.

Upriver landowner and businessman Leonard Thompson asked the tech committee during the same meeting what they were going to do about any particular problem the research might identify. Committee member Alden Vanden Brink, Rio Blanco Water Conservancy District manager, quickly answered that their mission was not to pursue any enforcement or regulations, that they’d hand all that off to the county commissioners.

The study has been funded in part by local, state and federal government entities including water conservation districts, the Rob and Melani Walton Foundation, Trout Unlimited, and additional grants/stakeholders. WRCD executive director Callie Hendrickson has been in charge of facilitation and oversight of the study on behalf of the county, through a contractual agreement with USGS.

In January of this year, USGS biologist Natalie Day shared some preliminary findings from the study, including information about what algae species were present during the 2018 bloom, some nutrient measurements, shear stress statistics, and streamflows. Her presentation coincided with analysis of stream temperature data by Brian Hodges of Trout Unlimited and analysis of macroinvertebrate populations on the river by Jennifer Lynch of GEI consultants. You can read that story at

More information on the subjects mentioned in this story can be found at,, and

In future coverage of White River algae blooms, we’ll explore the impacts of algae on the environment and economy, look into changes/developments on the river, explore research/study findings with experts and more. If you have a tip or suggestion related to these subjects, please email Those who wish to protect their privacy can remain anonymous. 

This reporting is partially funded by a grant from the CU Water Desk


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