PLAN or get SLAM'ed: Optimal management of invasive species in the presence of indirect health externalities.

This paper examines invasive species management when invasive species impact health outcomes indirectly through changes to environmental quality. For example, the emerald ash borer (EAB) has destroyed millions of ash trees throughout North America and has the potential to impact rates of cardiorespiratory mortality and morbidity through ash trees' ability to capture airborne pollutants. Optimal management inclusive of indirect health externalities may be different than status quo plans because the links between nature and health are complex, dynamic, and spatially heterogeneous. We produce a novel dynamic bioeconomic-health model to determine optimal EAB management in the face of such health effects. Our results show that including health increases net benefits of management substantially and that a "one size fits all" management approach is suboptimal given forest cover and demographic spatial heterogeneity. Net benefits to society are 873% higher and air pollution related mortality incidence is 82% lower when health externalities are included in management profiles using insecticide treatments and non-ash tree preemptive plantings without removal. Additionally, constrained managers optimally substitute toward preemptive tree plantings and away from insecticide use in the presence of indirect health externalities as a way to minimize disruptions to air quality. This paper has policy implications for the optimal management of environmental amenities.

Low-flow appliances and household water demand: an evaluation of demand-side management policy in Albuquerque, New Mexico.

Residential rebate programs for low-flow water devices have become increasingly popular as a means of reducing urban water demand. Although program specifics vary, low-flow rebates are available in most U.S. metropolitan areas, as well as in many smaller municipalities. Despite their popularity, few statistical analyses have been conducted regarding the effects of low-flow rebates on household water use. In this paper, we consider the effects of rebates from the Albuquerque Bernalillo County Water Utility Authority (ABCWUA). Using panel regression techniques with a database of rebate recipients, we estimate the marginal effects of various low-flow devices on household water demand. Results indicate a negative correlation between household water use and the presence of most low-flow devices, after controlling for water price and weather conditions. Low-flow toilets have the greatest impact on water use, while low-flow washing machines, dishwashers, showerheads, and xeriscape have smaller but significant effects. In contrast, air conditioning systems, hot water recirculators, and rain barrels have no significant impact on water use. We also test for possible rebound effects (i.e. whether low-flow appliances become less-effective over time due to poor rates of retention or behavioral changes) and compare the cost effectiveness of each rebate using levelised-costs. We find no evidence of rebound effects and substantial variation in levelised-costs, with low-flow showerheads being the most cost-effective device under the current ABCWUA rebate program. The latter result suggests that water providers can improve the efficiency of rebate programs by targeting the most cost-effective devices.

Economics of transboundary aquifer management.

This paper presents a general model of optimal water management for a transboundary aquifer under three different management approaches: cooperative, noncooperative, and myopic. Comparing the results from the approaches, we find the cooperative solution, where a single management plan is executed for all parts of the aquifer, results in the highest level of net social welfare, followed by the noncooperative and then the myopic. The trade-offs we find for the higher levels of welfare are lower use levels in the earlier periods. We present a short discussion of factors that can increase the inefficiencies of the models and suggest directions for future research.

A two-agent dynamic model with an invasive weed diffusion externality: an application to Yellow Starthistle (Centaurea solstitialis L.) in New Mexico.

This paper presents a bioeconomic model for two agents, a cattle rancher and a non-rancher, with interdependencies between their individual effort of invasive weed management and profitability. Dynamic simulations allow us to find numerically the optimal effort of weed control over a 5-year time horizon under a variety of beginning infestation levels. In a base-case scenario without governmental cost-share of control costs, we find that efforts to control the weed are not profitable. The base-case scenarios also indicate that grazing contributes to giving the invasive weed a competitive edge. A second series of simulations include incentive payments for weed control which are set at the minimum level required to have a net positive impact on the rancher's profitability. From these simulations, we find that the level of infestation impacts the size of the incentive necessary to get the agent to control the weeds and that the incentive payments impact the level of effort of the rancher. In addition, results reveal that the higher incentive payments for lower levels of weed infestations reduce the total cumulative incentive payments over time. Efficient policies directed towards management of invasive weeds may need to be adjusted for each individual case.