Integration of social perceptions, behaviors, and economic valuations of groundwater quality as an ecosystem service following exurban development

Abstract:

Millions of people rely on groundwater as a key, provisioning ecosystem service (ES). Our previous data suggested that drinking water nitrate concentrations and exurban development have significantly increased in the last three decades in Pocatello, Idaho, USA. Increased nitrate can lead to changes in ES and human values (such as water quality, people’s knowledge, and housing values). We predicted people who tested their water quality would be aware of nitrate contamination and its potential to affect their housing prices, and they would choose to invest in home drinking water treatment systems. To test these hypotheses, we measured nitrate concentrations in hundreds of drinking water wells in years 1985, 1994, 2004, and 2015. We conducted a randomized public survey to determine the degrees to which: (1) people tested their private well water for nitrate and (2) were concerned about health issues related to contamination; (3) how important water quality is for determining local property values; and (4) if people treat their drinking water. We then developed a biophysical model to understand how exurban growth, local geology, and time influenced groundwater nitrate. Finally, we applied an economic, hedonic model to determine if groundwater nitrate concentrations negatively correlated to property values. Aquifer boundaries, slope, rock and soil type were significant predictors of nitrate (ordinary least squares, α <0.05). The hedonic model suggested that although nitrate and local housing values were spatially heterogeneous and increasing through time, exurban growth and nitrate alone were not strong predictors of water quality or property values. We also present an integrated biophysical, economic, and social model to better understand people’s perceptions and behaviors of local nitrate pollution. Interdisciplinary ES and valuation may require multiple data types and integrated models to understand how ES and human values are influenced by exurban growth.