Water management, native plant communities and air quality in Owens Valley, California: A cost-effective ecological economic analysis of maintenance or restoration of alkali meadow communities

Background/Question/Methods

In Owens Valley, California the Los Angeles Department of Water and Power exports surface water (the Owens River) and groundwater (over 100 active pumping wells) from the valley over 4oo km south to Los Angeles.  Water diversions via the LA aqueduct have had significant hydrologic effects on surface and groundwater as well as ecological effects on native plant communities.  Owens Lake is now a playa and the largest single source of particulate matter (PM-10) air pollution in the United States.  Groundwater changes have caused a regional decrease in vegetation cover and there is new evidence that Owens Valley dust source regions are not restricted to the lake.  Native plant communities most impacted by groundwater decline are characterized as alkali meadow, which is dominated by salt grass (Distichlis spicata) and alkali sacaton (Sporobolus airoides), and requires groundwater to remain within approximately 3m of the surface.  Alkali meadows anchor soil thereby decreasing further dust sources and serve as essential habitat for numerous rare and endangered species.  In this study, a dynamic ecological economic computer simulation model was created to assess a cost-effective strategy of managing groundwater in Owens Valley while maintaining or restoring native alkali meadows.  

Results/Conclusions

Findings of this study indicate an adaptive approach for groundwater management (pumping high in wet years and low in dry years) is more cost-effective than historic status quo management in Owens Valley.  Net present value of costs of alkali meadow maintenance or restoration (in $2011 dollars over 50 years) averaged $67,458/acre for the status quo approach under baseline climatic conditions (foregone water benefits = $19,966/acre, restoration costs = $36,463/acre and lost ecosystem services = $11,029/acre).  Costs of maintaining alkali meadows with zero pumping of groundwater averaged $49,763/acre.  Costs of alkali meadow maintenance with an adaptive approach averaged $19,887/acre (foregone water benefits = $17,860/acre, restoration costs = $2,011/acre and lost ecosystem services = $16/acre).  Findings of this study suggest that changing to an adaptive water management strategy in Owens Valley provides a more cost-effective means to supply water, maintain native alkali meadows and ensure air quality than historic groundwater management strategies.