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Home Water Aquatic Species and Communities

Pope Marsh

Status and Trend

Interpretation and Commentary

Status: Somewhat Worse Than Target
Trend: Litle or No Change
Confidence: Low

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  • Relevance - Pope Marsh, managed by U.S. Forest Service – LTBMU, occupies roughly 150 acres adjacent to the City of South Lake Tahoe. It was formerly part of the wetland complex at the mouth of the Upper Truckee River, but development of the Tahoe Keys in the 1960s isolated Pope Marsh from the Upper Truckee River and dramatically reduced the size of what was the largest freshwater marsh and meadow complex in the Sierra Nevada (Manley et al. 2000).Pope Marsh is now dependent primarily on rain, snowmelt, and underground flow from Lake Tahoe for its water (Green 1991). Meadows, marshes, and fens have been identified in the Tahoe Science Plan (Hymanson and Collopy 2010) as special communities that are small in extent, but have great functional importance (Manley et al. 2009).Wetland vegetation plays an important role in recycling nutrients, trapping eroding soil, and filtering pollutants (Manley et al. 2000). This filtration capacity is critically important to protect the clarity of Lake Tahoe. Pope Marsh also provides important habitat for numerous species, including waterfowl nesting habitat.
  • Adopted Standards - Provide for the non-degradation of the natural qualities of any plant community that is uncommon to the Basin or of exceptional scientific, ecological, or scenic value. The Threshold Standard shall apply, but not be limited to, 1) the deep-water plants of Lake Tahoe, 2) Grass Lake, 3) Osgood Swamp, 4) Hell Hole, 5) Upper Truckee Marsh, 6) Taylor Creek Marsh, 7) Freel Peak Cushion Plan Community, and 8) Pope Marsh.
  • Indicator - The status and trend determination was based on a qualitative assessment of the natural qualities of a plant community. The natural qualities of a plant community include the current plant species assemblage, the health, age and ecological condition of those plant species, and the condition of the hydrologic regime.
  • Status – Pope Marsh is adjacent to Pope Beach, which is one of the most heavily used public recreation facilities at Lake Tahoe in the summer months. Most of the use is concentrated on the beach itself, but a long parking lot separates Pope Marsh from Lake Tahoe, and culverts connect the beach area to the marsh. The main impacts to the marsh are related to recreation; including disturbance of vegetation and wildlife by dogs, and some trampling from hiking and bicycling. A relatively large infestation of bull thistle (Cirsium vulgare) has been present at Pope Marsh for several years, and Eurasian watermilfoil (Myriophyllum spicatum) occurs in the standing water (USDA 2011a).Groundwater pumping from the Tahoe Keys potentially poses a threat to the hydrologic regime, and is likely leading to a gradual change in species composition (Green 1991; EPA 2000).

    Despite the adverse impacts to the area, recent Threshold Evaluations have assessed the status of Pope Marsh as in attainment, although the potential for decline was noted (TRPA 2007c).Management actions in the last five years have focused on facility improvements, hazard tree removal at Pope Beach, and control of known invasive plant populations at Pope Marsh (USDA 2011a). In 2007, the Angora Fire burned 3,000 acres within the sub-watershed that drains into Pope Marsh. Data collected following the fire suggests the fire had a negligible effect on lake clarity and algal biomass (TERC 2011a). Many erosion control and restoration projects have been implemented in the burn area, and it may be reasonable to conclude that the fire also had a negligible effect on Pope Marsh itself. However, the location of the wetland in the urban core, and the associated urban run-off and invasive plant infestations suggest that the natural qualities of Pope Marsh are not as intact as more remote wetlands like Hell Hole or Meiss Meadows. Most importantly, groundwater pumping from the Tahoe Keys is an on-going threat to the integrity of the marsh plant community (EPA 2000). Therefore, the status of Pope Marsh was assessed as “somewhat worse than target.”

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  • Trend Although the previous Threshold Evaluation considered Pope Marsh to be in attainment, and here it was assessed as “somewhat worse than target,” there is no evidence available to indicate there has been any particular decline in the last five years. The decline in the status in the present evaluation is based primarily on the location of Pope Marsh in the urban core, the on-going groundwater pumping from the Tahoe Keys, and the compromised hydrologic condition compared to marshes in remote areas. Therefore, the trend in the condition of Pope Marsh was considered to be “little or no change.”
     

  • Confidence – The confidence in the status and trend analysis was “low,” because both determinations were based on a qualitative assessment, and are not supported by sufficient quantitative data.
  • Human and Environmental Drivers - Pope Marsh was irreversibly altered by the development of the Tahoe Keys (Manley et al. 2000).Since then, humanactivities outside of the marsh (e.g., groundwater pumping, development, and management of lake water levels) impact the hydrology within the marsh (EPA 2000). These anthropogenic stresses on Pope Marsh increase sensitivity to naturally occurring stressors, and likely will initiate gradual changes in the plant community composition of the marsh, which could dramatically change the effectiveness of the marsh as a filter of nutrients and sediments (EPA 2000).Other human impacts include the introduction of invasive plants, dogs, and some trampling from hiking and bicycling. As with other wetlands, extended drought and climate change pose a threat to the system.
  • Monitoring Approach – The status and trend determinations were based on a qualitative assessment of factors influencing the condition of the site, including historical alterations, on-going hydrologic impacts, sources of recreation-related disturbance, and surrounding land use and resource management. However, in the future it will be possible to base the evaluation on quantitative vegetation monitoring data. Permanent plots following the protocol in the Region 5 Range Monitoring Program were installed at Pope Marsh in 2004 (Weixelman et al. 2003). The plots were re-visited in 2009/2010, but the data have not yet been analyzed (Engelhardt and Gross 2011). The program is designed to quantify changes in the ecological condition of wetland plant communities. The protocol is designed to classify meadows and wetlands according to dominant plant species, elevation, and site moisture characteristics, and then use a quantitative ecological condition scorecard for that meadow type. The user assigns an ecological condition of low, moderate, or high based on plant species composition, the presence of different plant functional groups, and other hydrogeomorphic variables. The protocol also provides information on the environmental conditions necessary to support certain rare species, and the monitoring design allows for quantitatively tracking rare species abundance.
  • Monitoring Partners – U.S. Forest Service Lake Tahoe Basin Management Unit, California Native Plant Society

Links

 
  • Monitoring Plan
  • Conceptual Model

Map

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Map showing location of Pope Marsh and surrounding area.

Additional Info

References

Additional Information

Last Updated on Tuesday, 02 October 2012 13:01