Saving the Colorado River Delta: How Much is It Worth?

The Colorado River is a river system spanning seven states in the United States (US) and two in Mexico. Water in the river has been over-allocated, which has led the Colorado River Delta in Mexico to dry up, thus endangering the indigenous species. The two nations made several temporary, costly allocation agreements to transfer water to the Delta for ecological restoration. However, there is still no long-term economic solution for the Delta, which is what this study aims to address. In this work, I investigate solutions for rerouting water to the Delta that will minimize costs without causing excessive damage to the agrarian economy in the US. The cost of conserving water for the Delta was analyzed using numerical simulations with crop data from the Imperial Irrigation District in California. The objective is to find a policy that would help allocate 100,000 acre-feet per year to the Colorado River Delta at a minimum lifetime cost. Two scenarios are studied that would yield enough water for a sustainable restoration of the ecosystem: fallowing croplands and changing the irrigation system to be more water-efficient. Results indicate that fallowing 20,000 ac of alfalfa would be the least costly way of accumulating this resource at a cost ranging from $5.5 million to $13 million per year for a 31-year time horizon. This paper provides new insight into ways in which the US and Mexico can secure the future of ecosystems like the Colorado River Delta.