Environmental Reviews & Case Studies: Surface Water and Groundwater Interaction, Management, and Conflict in Colorado: Alarming Trends for the 21st Century

Abstract

Groundwater and surface water are hydraulically connected in some regions of the world. This type of aquifer system is called a tributary aquifer and can affect flows of adjacent streams. These accretions occur when slowly moving groundwater enters the bottom or side slopes of a stream, providing base flow. In this situation, groundwater becomes surface water. Groundwater that is hydraulically connected to surface water in this manner is called tributary groundwater. Colorado state law requires all water users—of both surface and tributary groundwater—to follow a strict water-right priority system of “first in time, first in right.” This Doctrine of Prior Appropriation, adopted in Colorado in 1876, is rigidly followed today. Since 2003, thousands of tributary groundwater irrigation wells have been curtailed from pumping (legally shut off) due to pumping depletions that reduce stream flow. The impacts to these groundwater users have been serious. Approximately 2,000 wells have been curtailed and will never pump again, and tens of thousands of acres of productive agricultural lands have been reverted to dryland crops or weeds. Surface and tributary groundwater use conflicts are inevitable in locations where rigid water-allocation systems are followed. Nobel Prize winner Eleanor Ostrom points out that common-pool resource management requires collective-choice arrangements if resource users—in this case, surface water and groundwater users—are to develop a stable management plan. This article will show that the Colorado Constitution prohibits such an arrangement and is the reason thousands of tributary groundwater wells have been permanently shut off in the state. By contrast, other states and regions of the world may be able to avoid drastic well curtailments if state or federal laws allow for common-pool resource management.