Caldor Fire Citizen Science

Combining science, community engagement and advocacy to Keep Tahoe Blue

WATCH: Stream Impact Monitoring
Follow along with the League's Pipe Keepers volunteers as they test for stormwater pollution flowing off of areas burned by the Caldor Fire and toward Lake Tahoe.


A robust, adaptable, citizen scientist-fueled program to monitor water quality in streams and rivers that drain areas burned by the Caldor Fire. This work – including visual assessments, and qualitative and quantitative data gathering – complements the rigorous scientific monitoring conducted by public agencies through the Lake Tahoe Interagency Monitoring Program (LTIMP).


To measure, sample and assess the water quality in streams and rivers that carry water from the Caldor Fire burn scar to Lake Tahoe. To identify sites that should be prioritized for ecosystem restoration work in the summer of 2022. To engage the Tahoe community in important environmental stewardship efforts.


Citizen scientist volunteers trained by the League. Any Tahoe community member is welcome. No past experience is required, just the drive to Keep Tahoe Blue.


Ten sites along the Upper Truckee River and Cold Creek (see the map). Sites were selected based on proximity to land burned in the fire, and to cover areas above and below the burn scar and existing ecosystem restoration projects. Sites may be added as needed.


During the 2021/2022 winter storm season, with at least monthly sampling from October 2021 – June 2022. Our sampling efforts kicked off during the first major storm of the season, which arrived on October 24, 2021. Additional sampling events can be added where and when needed, based on weather conditions, erosion reports and the like.


The League’s science experts designed the monitoring program and trained community members to adopt sites and conduct monthly monitoring following standard methods and protocols, including quality assurance and quality control. The League shares results with agency partners in the Lake Tahoe Interagency Monitoring Program (LTIMP).

A Pipe Keepers volunteer collects water samples. Pipe Keeper volunteer Loretta Friedel collects a water sample from the Upper Truckee River. January 2022.


The Caldor Fire was the largest wildfire to ever burn in the Tahoe Basin, touching 10,000 acres and impacting the Upper Truckee River watershed. Vegetation that once covered the steep slopes in the burn scar has been replaced with charred trees, ash and bare soils.

As the winter storm season delivers precipitation to the Basin, rain and snow can trigger large erosion events and debris flows that move fine sediment and ash particles downhill and into the streams and rivers that empty into Lake Tahoe. This stormwater introduces nutrients that can encourage algae growth and degrade water clarity. The USDA Forest Service’s burned area emergency response (BAER) report further describes the anticipated impacts on the Tahoe Basin watershed.

Our citizen scientists’ data collection complements the professional, robust water quality and stream flow monitoring that takes place through the Lake Tahoe Interagency Monitoring Program, which uses autosampler devices and stream flow gauges at fixed locations around the Tahoe Basin. The League advocated for the expansion of LTIMP, knowing the data it produces would be crucial to understanding how wildfire can create delayed aftereffects for Lake Tahoe. The program expansion was approved, funded and partially implemented in late October 2021.

The collaboration between scientists, public agencies, research institutions, nonprofit organizations and community members will build understanding of the environmental impacts of wildfires; identify priority areas to address; and help implement solutions to protect, preserve and Keep Tahoe Blue.

Trees blackened by the Caldor Fire. Trees blackened by the Caldor fire on the slopes above South Lake Tahoe. December 2021.

Stream Monitoring Data Map

The monitoring sites in this map were selected based on proximity to burn areas and location relative to existing restoration projects. Monitoring activities will include water sample measurements in-situ (dissolved oxygen, air and water temperature, pH, total dissolved solids, electrical conductivity), water sample collection for lab analysis of nutrients (total nitrogen, nitrate, total kjeldahl nitrogen, ammonia, filtered phosphorus, phosphate, organic phosphate) turbidity, visual assessment of the surrounding stream banks (cloud cover, precipitation, wind, water clarity, instream flow, presence of possible pollutants, bankfull width, depth, percent of streamside vegetation) and photos (upstream, downstream and across from sampling location).