To many, Grand Canyon is a vast, dry desert landscape. When Spanish explorers came looking for the Seven Cities of Gold and initially saw the Grand Canyon, they thought it was inhospitable and deemed it valueless, truly misjudging the scale of the river from the rim of the canyon. Water supports life, and to these early visitors it appeared as if there was none accessible. What they, and many today, fail to realize is that water is tucked away in the recesses of small side canyons, largely out of view to most park visitors. The springs and seeps of Grand Canyon National Park truly are the lifeblood of the canyon, supporting the development of one of the world’s most ecologically diverse areas and sustaining a 12,000-year human history, including the current water supply for millions of annual visitors.
Now, the National Park Service’s hydrology team is conducting important research on understanding the plumbing and vulnerability of seeps and springs at Grand Canyon. Supported in part by funding from the Grand Canyon Association, hydrologists started using non-toxic dyes to learn more about the source of water at springs in the Grand Canyon. This research is critical as these locations not only provide valuable drinking water to wildlife and humans, but are also incredibly vulnerable to climate change, development and contamination. Large springs that form creeks provide habitat and create lush riparian areas. Arizona lost nearly 90 percent of its historic riparian areas due to development, agriculture and groundwater pumping. From a cultural standpoint, springs and seeps are considered sacred to the culturally affiliated tribes of the canyon and frequently play prominent roles in oral histories and culture.
The porous fractured rock at the rim transports rainfall and snowmelt, which would otherwise be lost to evaporation, vegetation and runoff to the subsurface. Even so, only a tiny fraction of precipitation makes it into the canyon’s aquifer systems. Groundwater then runs downward along faults, fractures and through cave systems, ultimately emerging as springs where the water stops at low porosity layers (notably the Bright Angel Shale). It is estimated that Grand Canyon contains more than 1,000 springs and seeps, although the total number will not be known until a systematic survey is completed (currently underway by the NPS and park partners).
The park’s hydrology team recently added four different colored, non-toxic dyes to sinkholes on the rim of the canyon to determine how fast the water moves from the plateau to the springs and to see which sinkholes are connected to which springs. This ye is collected monthly at each spring using activated charcoal packets the size of a tea bag. The park monitors springs as far upstream as South Canyon to Deer Creek with charcoal being retrieved, sent in for testing and replaced with new charcoal.
Over numerous years of study and dye injections, we will learn more about the plumbing, vulnerability and the importance of park water resources than previously known. With this important information, hydrologists will determine the current health of the systems and investigate long-term trends. The data is especially useful in quantifying the effects of ongoing and potential future impacts to springs and seeps and their related ecosystems. This work is especially important with record visitation to the canyon, the newly planned TransCanyon Pipeline, forecasted climate change in the Southwest, existing uranium mining claims and potential developments along the park’s boundaries
Many of the recharge basins of Grand Canyon springs extend well beyond the park boundary, making them susceptible to outside threats. Activities and processes such as North Rim bison, groundwater pumping, uranium mining and climate change potentially could impact these important water sources. Some of these activities and processes can be devastating, causing reductions in flows in creeks that are home to endangered species including the Humpback Chub and Kanab Ambersnail.
Declines in the flow of a small spring or seep may change a perennial system into an intermittent one, or more significantly, dry the system out completely. Species that rely on these water sources, such as riparian plants, fish, amphibians and invertebrates, often do not have a mechanism to move across the desert landscape to the next water source, and because of this, unique and endemic species may be lost.
Thanks to the members and donors of Grand Canyon Association (GCA), in 2015 funding provided the park three hydrological technicians and one paleontologist. GCA funding also provided field equipment for hydrology interns, volunteers and maps. In addition, these contributions allowed the park to send four interns to the 2015 Geological Society of America Conference in Baltimore, MD where Grand Canyon interns presented their individual hydrology and paleontology studies to an international audience. This important research is aimed at better understanding the mechanisms that supply the springs and seeps of Grand Canyon so that better management and protection will ensure that they continue to provide for the environment as they have for tens of thousands of years.