The Colorado River is the life force that powers the Southwestern United States. Historically flowing west out from the Colorado Rockies, the river nourishes life down Utah, across northwest Arizona, then snakes down the state line of California until finally entering the California Gulf from Mexico. The river’s power is what cut the Grand Canyon and formed the famous geology of Canyonlands. Its water sustained the growth of Las Vegas, Los Angeles, and Phoenix in water supply and power as it flowed through dams such as Hoover. The end of the river, which exits into the California gulf in Mexico formed one the largest river deltas in North America, sustaining a complex system of wetlands filled with endemic species such as the totoaba (NOAA Fisheries), the vaquita, salt grass, the delta mudsucker (Swift), the clam Mulinia coloradoensis, subspecies of the Yuma clapper rail (Patten), desert pupfish (Hendrickson), etc. Since the 20th century however, many of those endemic species have become vulnerable or endangered (the aforementioned vaquitas have only an estimated 12 individuals left in their population (Mongabay), and the clam Mulinia coloradoensis, once the most abundant clam in the delta is now scarcely seen (Rodriguez)). The Colorado’s riparian banks were equally impressive, with endemic fish like the Little Colorado spinedace, the razorback sucker, Bonytail chub, the humpback chub, and the Las Vegas dace, as well as endemic springsnails and and Vegas Valley leopard frog (FEOW). Now, however, all of the mentioned species are in danger of extinction, except for the Las Vegas dace and Vegas leopard frog which are extinct (IUCN, IUCN). Clearly the great river that carved out the southwest no longer sustains the life it once did, the wetlands in the delta are only a fraction their size, and for much of the past century, the Colorado River no longer reached its end.
Rapid southwestern development transformed the unpredictable and turbulent surges into a tightly controlled series of dams and reservoirs. Both the river itself and the tributaries that feed it are relied upon for household needs, industry, irrigation, and tourism, demands that only increase as the population grows, not to mention waste from invasive species and reservoir evaporation. Because of this, so much water is stored in reservoirs and consumed from the Colorado that, until a U.S.-Mexican agreement in 2014, the water didn’t even reach its end at the Colorado River Delta; a change that has shrivelled up much of the wetlands there (Zielinski).
In addition to the clinching of water resources, sediment and silt deposits have also been reduced. The delta thrived off the nutrients carried down from the Colorado Basin, but dams block the sediment on its route. Less than 0.5% of the historic annual average amount of sediment is discharged (Villaescusa). Instead of being fed into the delta, the sediment sits the reservoirs behind dams. To make matters worse, sediments tend to increase the surface area of water bodies, and therefore also increase evaporation; plants also grow off the stagnant water sitting in reservoirs, causing loss through evapotranspiration (Maddock). The sediment blockage not only causes nutrient loss, but exasperates the water usage as well.
In addition to the shortage of resources to the Colorado River Delta, the interruption of water and sediment flow has changed the chemical composition and geology of the delta. For thousands of years, the estuary relied on the contrasting forces between the freshwater and sediment river outflow and the saltwater and tidal ocean inflow. Without the pressure of the river to mitigate the effect of the ocean, saltwater has dominated much of the estuary, and the change in water circulation has eroded its banks (Carriquiry). As the salinity of the delta increases, it becomes more difficult to sustain plant life, which has allowed invasive species a leg over native ones (Glenn). Invasive species are guilty of draining the river as well. The most visibly obvious is the Tamarix, or salt cedar trees. These species, among others, not only compete with native species for nutrients and space, but also interfere with infrastructure, just like the the invasive mussel C. caspia which appears in Lake Powell, Lake Mead, Lake Mohave, and Lake Havasu, and is known to interfere with the dams there (Pucherelli). Quagga mussels are similar threats. Overall, the human impact on the Colorado River has been disastrous to both the southwestern ecosystem and the Colorado River Delta.
Recently citizens and institutions have recognized the ecological importance of the Colorado River and initiated programs to repair and protect the threatened land. In 2014, Minute 319, an agreement between the U.S. and Mexico, allowed the opening of the Morelos Dam to allow a pulse flow to reach the river delta (The Natural Conservatory). This pulse of water was the first contact between the Colorado and the delta in 16 years. Before, the only freshwater to reach the delta was runoff from upstream farms. Directly after the pulse, the region saw an expansion in seed germination and bird abundance and species richness (Flessa). Follow ups from 2017 reported that bird abundance in the area increased by 20% and species diversity by 42%. Initially after the pulse, greenness increased by 17% the following year, but has since declined (Flessa). Minute 219 expired December 2017, and led the way for Minute 232, signed in September 2017, which secures Mexico’s ability to store water in Lake Mead (formed by the Hoover dam), and provides funding for water efficiency projects, restoration work, and scientific research.
As for the water that actually makes its way down stream, treatment plants have been set up to control the salinity of the river’s water. In 1974, the Colorado River Basin Salinity Control Program was created and has since reduced the river’s annual salt load by “more than 1.3 million tons” by the time it reaches Imperial Dam (Colorado River Basin Salinity Control Forum). To remove invasive species from the area, both community and bureaucratic organizations have undergone projects to remove invasive species. The National Wildlife Refuge System set up an “Invasive Species Strike Team” to complete such a mission (Invasive Species). In 2010, they removed Salt Cedar trees, Russian thistle, Sahara mustard, and giant salvinia from the southwest, and since 2003 funded and assisted many local initiatives (Invasive Species Strike Teams).
Future strategies should focus on improving the environment’s access to the Colorado river throughout its basin and delta. Particularly important is focusing on reducing consumptive water usage. Consumptive water use is water use that does not return to the water system, and instead, is either stored away from reintroduction to the water system, such as industrial processes, or is evaporated, and must pass through the water cycle before it can be used again. Household water, non-consumptive usage, such as showers, washing, sinks, toilets, etc, are treated as waste water and returned to be reused. Watering the lawn on the other hand, is consumptive usage, both because evaporation of the water not-yet soaked into the ground and evapotranspiration, the evaporation of water from leaves. The latter is the area of water use that conservationists should focus on, rather than water use as a whole. Cutting down on household appliances may only encourage people to spend more watering their grass, a habit that is counter intuitive for water conservation.
Irrigation is the largest user of consumptive water use (Upper Colorado River Basin Consumptive Uses and Losses). A first step would be to discourage water-greedy plants, such as turf grasses. WaterSense, an EPA-ran program, is already making strides to promote more water-efficient landscaping, such as Xeriscaping (WaterSense). Furthermore, engineering and agricultural techniques can help to cut down on the water spending. Technology such as variable rate irrigation and drip irrigation have proven to cut down on water usage by applying water only where it is needed, and in the case of the drip irrigation, directly to the roots to prevent evaporation (Gies). More advanced technologies such as biodomes (structures that cover the land and collect condensation) would also be water efficient by not losing water to the inevitable evapotranspiration. The UK’s Eden project is an example of research in this area (Eden Project).
In order to permit river sediment to reach ecosystems downstream, dams can be engineered to route particles around or through a reservoir, thereby reducing build up around dams. Sediment bypasses include flood bypass channels and bypass tunnels (above or below water stream) allow faster moving water one direction, and heavier slower sediments (which tend to settle near the bottom) in another (Boes). Flood bypass channels can reroute sediment in a similar fashion. Sending sediments downriver, and out of reservoirs, is within hydroelectric plants’ and dams’ best interest as well. Buildup of sediment can bury water outlets and inlets, bury ramps and marina infrastructure, interfere with sensing and navigation equipment, and damage pumping equipment (Reservoir Sediment Management). Therefore, machines that separate particles from the water to be sent downstream would improve the longevity of the dams and provide ecological benefits to the Colorado’s riparian environments.
The Colorado provides several benefits, and is indispensable to life in the arid southwest. The river itself is a tourism hotspot for all the states it runs through; rafting, camping, hiking, and swimming destinations attract visitors all over the world to Glenwood Springs, Lake Mead, the Grand Canyon, and more. Even beyond the state level, Native American tribes have benefited from river tourism, some notable examples being the Hualapai skywalk over the Grand Canyon to the Havasupai falls in the Havasu canyon (NPS, NPS). An economic report by river-reliant companies estimated that if the Colorado River was a company, all the recreation revenue would earn it 155th on the Fortune 500 list (Tory). The riparian and delta ecosystem has provided resources for the communities that live there for centuries. The water itself is a crucial resource of course, but clam harvesting, fishing, and living in a lush community of nature is a valuable resource as well (Howard). The Colorado River is a resource so valuable that farmers and recreationalists across the basin are willing to fight for its security.
Patten, M. A. (1998). YUMA CLAPPER RAIL.
Abell. (2000). 130: Colorado. Retrieved from http://www.feow.org/ecoregions/details/colorado
Carriquiry, J. D., Villaescusa, J. A., Camacho-Ibar, V., Daesslé, L. W., & Castro-Castro, P. G. (2010). The effects of damming on the materials flux in the Colorado River delta. Environmental Earth Sciences, 62(7), 1407–1418. doi: 10.1007/s12665–010–0626-z
