CONSERVATION CORNER: Algae Study Update

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The White River Algae Study is on schedule with all the data collection being complete for the three-year study. The U.S. Geological Survey (USGS) will now analyze all the data they have collected and provide a final report in late 2021.

The USGS staff presented an update to the White River Algae Study Technical Advisory Committee (TAG) via a virtual meeting on December 8th. The USGS PowerPoint presentation is available on the White River and Douglas Creek Conservation Districts’ Algae page of their website at www.whiterivercd.com or you can link directly to the presentation by scanning the below ZapCode.

Key findings of the historical data analysis and literature review include: 1) Increases in phosphorus and to a smaller degree, nitrogen concentrations and loads at mainstem and tributary sites during the last 20 years, 2) Other rivers in the West are experiencing algae blooms, 3) Nutrient availability and physical disturbance during high streamflow can play a large role in controlling blooms.”

New data collection of physical, chemical, and biological factors includes:

  • 1) High-flow condition measurements,
  • 2) Channel surveys, grain-size analysis, continuous water-quality monitoring,
  • 3) Water-quality sampling,
  • 4) Algae sampling- Chlorophyll a and taxonomy,
  • 5) Isotope sampling (Nitrogen source analysis)
  • 6) Nutrient load/source area analysis.

The USGS presentation provides graphical representations of nitrate, total nitrogen, orthophosphate and total phosphorus concentrations during spring runoff and summer sampling events. Concentrations of nitrate, total nitrogen, and total phosphorus were greatest during spring runoff sampling events in 2019 and 2020. The total nitrogen : total phosphorus ratio at the South Fork site, directly below the Cabin Lake fire, was elevated in 2019 relative to 2020, indicating greater nitrogen export following the fire. USGS reported much higher algae concentrations in the river in 2018 than in 2019 and 2020.

Please contact the District office at 970-878-9838 with any questions.


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