Economic returns of groundwater management sustaining an ecosystem service of dust suppression by alkali meadow in Owens Valley, California

Highlights

• We model economics of groundwater management in a well-field in Owens Valley.

• We examine effects of groundwater management strategies on alkali meadow communities.

• We examine effects of groundwater management strategies on economic rent.

• Adaptive groundwater management sustains native alkali meadow plant communities.

• Adaptive water management generates more economic rent than status quo management.

Abstract

This paper addresses the economic tradeoff between pumping groundwater and maintaining a native plant community that provides an ecosystem service of dust suppression. A dynamic ecological economic simulation model was created to assess net benefits of production (i.e., economic rent) from groundwater management while requiring a producer to maintain or restore native groundwater dependent vegetation in a well-field in Owens Valley, California. Historic groundwater withdrawal during dry conditions followed by recharge during wet conditions has reduced vegetation cover, soil stability and contributed to the drying of springs and seeps. Findings indicate adaptive management that pumps less water, but high volumes in wet years and low volumes in dry years, generates greater economic rent while supplying water, sustaining alkali meadow and maintaining dust suppression. Adaptive management generates economic rent of $82.6 million (in 2011 $) compared to status quo management of $30.5 million over 50 years pumping less annual groundwater than status quo at respective levels of 73% (6830 acre-ft; baseline conditions) and 56% (4952 acre-ft; climate change scenario). Under a climate change scenario and a 2.0 m root-zone or less, it would be cost effective to cease groundwater pumping rather than incur substantial restoration costs of the native plant community.

Introduction

In many arid mountain basins worldwide, groundwater is managed as a dynamic reservoir, providing additional water supply during years of insufficient surface runoff. In the Great Basin of the western United States, groundwater is often shallow and recharged annually to within the root zone of native plants. In such systems, groundwater withdrawal and recharge has potential to replace surface reservoirs and associated water losses through evaporation. However, shallow groundwater supports facultative wetland species, which provide important ecosystem services such as dust suppression, soil stability and air quality. Research into the hydroecology of these systems at our field site in the Owens Valley, California, has led to sufficient understanding to develop empirical relationships between snowpack runoff, groundwater depth, and vegetative cover within the native ‘alkali meadow’ plant community (see Fig. 1). Alkali meadow supports rare, threatened and endangered species, helps to maintain soil stability and enhanced air quality, is extensive throughout the Owens Valley and to a lesser extent in other valleys of the Great Basin and Range, and is the target of conservation due to its dependence on shallow groundwater that is pumped for human use throughout most of its range.

Valuation of market and non-market ecosystem services and the incorporation of these values into natural resource decision-making have increased over the last two decades (Daily, 1997, deGroot et al., 2002, Polasky, 2008, deGroot et al., 2010, Wratten et al., 2013). Extensive valuation studies have been conducted on an array of ecosystem services such as, but not limited to, carbon sequestration, water supply and purification, flood and drought buffering and biodiversity (Van Wilgen et al., 1996, Daily, 1997, Gutrich and Howarth, 2007, deGroot et al., 2010, Wratten et al., 2013). Yet few studies have addressed the ecosystem service of dust suppression by plant communities and the links to hydrology and water management (Krieger, 2001, deGroot et al., 2002, deGroot et al., 2010). This study contributes significantly to efforts to capture the non-market value of ecosystem services in natural resource decision-making by articulating the non-market value of dust suppression by native alkali meadow plant communities and utilizing it to inform groundwater management strategies.

A dynamic ecological economic simulation model was created to assess which groundwater management strategy in the Taboose–Aberdeen well-field of Owens Valley maximizes the net gains of groundwater production (i.e., economic rent) while sustaining or restoring native alkali meadow. In consideration of over $1 billion dollars in outlays thus far for restoration of dry Owens Lake and the continued degradation of meadows to the north of the playa, this study analyzed the costs of restoration of alkali meadow, temporal loss of ecosystem services from meadow degradation, and compared these costs to net revenues generated from groundwater extraction by the Los Angeles Department of Water and Power (DWP). Restoration costs are relevant to analysis of the economic rents derived by DWP from groundwater pumping because historic agreements have required maintenance of alkali meadow and federal law requires a specified level of air quality. Los Angeles DWP is constrained by the Inyo-LA Long Term Water Agreement (LTWA; Los Angeles and County of Inyo, 1991) to avoid adverse impacts to native plant communities and is required to meet the particulate matter PM-10 standard of the National Ambient Air Quality Standards (NAAQS) under the Clean Air Act. Los Angeles DWP is required to manage groundwater resources in Owens Valley without causing significant ecological effects that cannot be successfully mitigated and to avoid causing decreases in vegetation cover or changes in vegetation community structure (Los Angeles and County of Inyo, 1991). Thus, an analysis of how groundwater can be managed to maximize economic rents while sustaining native alkali meadow and the ecosystem service of dust suppression in Owens Valley is imperative.