by Adin Bonapart
Water storage and distribution infrastructure (dams) allow large areas of land that wouldn’t otherwise have access to water (i.e. away from riparian areas) to be farmed and settled. Furthermore, dams give farmers security against variations in climatic conditions and water supply (i.e. droughts), which, allows farmers to grow higher-valued, more water intensive crops. Hansen et al. (2014) find that the presence of dams has a “small, positive, but non-significant effect” on farmland values. For these reasons, the construction of dams tends to lead to improved crop yields and planted acreage.
Hansen et al. combine spatiotemporal data to examine the impact of major dams on irrigated agriculture and the natural environment in Idaho. In many regards, this study is successful in illustrating the relationships and interdependency between modern agriculture and major water storage projects. Irrigated agriculture is responsible for about 85% of all water withdrawal in Idaho, and about half of all major dams in the state list irrigation as one of the essential purposes. Overall, the authors argue that the development of major dams is beneficial for the agricultural sector, although they maintain that dams are generally detrimental to the natural environment.
Agricultural irrigation practices and large dams are connected with negative ecological impacts as a result of diverting and depleting water from streams and rivers. Such artificial changes to the watershed affect fish and other wildlife, degrade water quality by changing the salinity of the water, and disrupt natural flows that can have devastating consequences native fish populations. But, Hansen et al.’s assessment on dams and the natural environment is lacking in these quantitative data. The study gives measurements on annual and seasonal stream flows along a major river in Idaho and touches on the intersection of ecological problems and agricultural land use, but it does not attempt to quantify any ecological data. While, in the title and in the abstract, the authors claim to evaluate the comprehensive long-term impacts of dams on the natural environment, they do not attempt to incorporate any ecological costs of dams into their models, nor do they investigate the connection between the integrity of aquatic ecosystems and the sustainability of these water supplies.
That the authors didn’t explore the ecological affects of dams and agriculture is emblematic of the current conceptual rift between human behavior and ecological relationships that is present in agricultural and natural resource systems today. The current water “regime” in Idaho is built upon antiquated 1800’s conceptions of property, including the priority in appropriation (first in time first in right) clause, which is a highly human-centric and problematic land ethic in the context of a globalized world characterized by ecological crises and resource mismanagement. Hansen et al. are vastly limiting the usefulness of their study when they consider agriculture and the natural environment as two separate “sectors,” rather than one system of interconnected parts. If the authors had considered the long-term ecological impacts of dam construction and mass irrigation projects, their conclusions might have been significantly different.
Hansen, Z., Lowe, S., Xu, W. 2014. Long-term impacts of major water storage facilities on agriculture and the natural environment: Evidence from Idaho (U.S.). Elsevier Science Direct, Ecological Economics 100, 106-118. http://www.sciencedirect.com/science/article/pii/S0921800914000196.