• Rainbow over Half Dome


    National Park California

Visitor Use and Impact Monitoring

Yosemite National Park’s Visitor Use and Impact Monitoring Program collects information about the extent of human-induced impacts on natural and cultural resources and the visitor experience. The progress of the program’s long-term monitoring efforts can be viewed through field monitoring guide updates and annual reports, posted online as available.

Although the program provides parkwide visitor-use monitoring, much of its recent effort relates to the Merced and Tuolumne Wild and Scenic River planning efforts. Upon release of final environmental impact statements for both river plans, updated visitor-use reports and monitoring protocols will be made available. Note that program documents do not represent the final suite of indicators selected for inclusion in the draft river plans.

The abbreviated documents below demonstrate the processes for selecting and implementing indicators and standards. These documents introduce guiding legislation, management systems that have been in place for decades, and the latest park initiatives to establish standards, indicators, and monitoring programs for visitor experience and resource protection. View annual reports and field monitoring guides from past years and other visitor-use references online. For any questions on the monitoring program, contact the coordinator by email.

Introduction and Overview: This section qualifies the Visitor Use and Impacts Monitoring Program through the explanation of indicators and standards. Indicators and standards, in turn, help guide management decisions. Accomplishments from the 2010 field season include monitoring sites selected and sampled, and collaborative efforts with non-federal professionals. [685 kb PDF]

Water Quality: Baseline data from 2004-2007 was used to inform the selected indicators of water quality for the draft Tuolumne River Plan. These include nutrients (total dissolved nitrogen [TDN], nitrate + nitrite [NO2NO3], total phosphorous [TP] and total dissolved phosphorous [TDP]), E. coli, and total petroleum hydrocarbons (TPH). [396 kb PDF]
Riverbank Condition: Human use of riverbanks can exacerbate the normal riverbank erosion processes. This indicator group examines vegetation condition and channel morphology at 28 sample sites along a 17km stretch of the Merced River in Yosemite Valley. [404 kb PDF]

Informal Trails in Meadows: Extent and condition of informal trails in meadows was measured with four different indices, weighted mean patch index, largest five patches index, total impact extent, and condition class. [349 kb PDF]

Soundscapes: The human perception of the acoustical environment is referred to as the soundscape. This is an important element to a healthy ecosystem. Yosemite’s Soundscapes are being monitored in both wilderness and non-wilderness areas and samples are stratified between nighttime and daytime hours. [411 kb PDF]

Archeological Site Condition, Stability and Integrity: Site condition data, collected at each of the 87 sites in the Tuolumne and Merced River corridors, were recorded on an ASMIS field form, and supplemented with additional data specific to visitor-related impacts. [884 kb PDF]
Extent of Visitor Use: A variety of visitor use data was collected during the 2010 field season including vehicle counts at entrance stations, people at one time (PAOT) at destination sites and automated counters on designated trails. [752 kb PDF]
Wilderness Encounters: The major focus for the 2010 field season was the integration of data collection methods developed and field tested during the 2009 pilot study (Broom & Hall, 2010). Encounters were measured as any group or person within a 25 foot speaking distance of the trail and the data collector. [431 kb PDF]
Wildlife Exposure to Human Food: This indicator was measured by the number of compliant campers with food storage regulations. There were two regulations monitored-Vehicle violations in campgrounds, and parking lots and campsite food storage violations. Five campgrounds were sampled with a total of 51,326 campsites inspected and 72,474 vehicles inspected. [331 kb PDF]
Field Monitoring Guide: Field sampling methods and analytical protocols associated with the Visitor Use and Impacts Monitoring Program are guided by Yosemite’s Field Monitoring Guide. This document reflects the most current procedures and is updated to represent any significant changes as they occur. [4.6 MB PDF]

Reference: This is a compiled list of references for citations that appear throughout the summary reports above. [1 MB PDF]

  • Social Science: Yosemite's scientists study visitor-use management, impact monitoring, and planning.
  • Research and References: View visitor-use archived reports
  • Weekly Yosemite Traffic Forecast: View a traffic forecast based on the three most recent years of traffic data.

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