Part 2 of a two-part article summarizing the results of a two-year groundwater study initiated by California Trout.
The recharge area for a spring is determined based on a regional meteoric precipitation line established by a hydrogeologist by the name of Rose, that measures at what elevation precipitation drops different isotopes of hydrogen and oxygen. Heavier isotopes fall at lower elevations and lighter isotopes fall at higher elevations.
Of the springs sampled for hydrogen and oxygen isotopes, the data indicates that the recharge zone for all of the springs is above 5,200-feet, and thus lies within the protection of the Mt. Shasta Wilderness boundaries.
“It is fortunate that the recharge area is fairly protected from possible contamination from development,” said Unkefer. “As far as water quality goes, there still remains the question of cloudseeding and other contaminants in our environment. The biggest question, however, may be how water supply will be affected by climate change.”
Fluctuation in spring
Most of the springs measured for discharge were fairly constant with the exception of Esperanza Springs, Bear Springs, Panther Springs, Black Butte Springs and Cold Creek Springs.
Long time residents say they have not seen much fluctuation in Bear Springs. In the last few years, to their surprise, people have found the spring dry.
Over the course of the study, Unkefer said that Bear Springs has been dry in the spring, flowing in the summer, dry in the fall and buried in the winter. “This indicates that the spring is fed by snowmelt in the summer,”?she said. “The recharge and discharge elevations of Bear Springs and Cold Creek Springs are similar, and while Cold Creek is a much bigger spring, it also fluctuates similarly to Bear Springs, with peak flow in the summer.”
In late 2007 Panther Springs, the sacred spring of the Winnemem Wintu, went dry for the first time in their tribal memory.
“Continuing to correlate current spring discharge with anecdotal evidence from the past and with weather data will help us forecast water supply and the vulnerability of different springs into the future,” Unkefer said.
Climate change and the glaciers
In the summary report Unkefer discusses the Glacier study published in 2006 by Howatt et al. The study used two predictive models to forecast precipitation and temperature through 2100. The Summary Report poses questions as to how different precipitation and temperature scenarios will affect the timing and discharge of springs on the mountain, especially if more precipitation comes as rain instead of snow.
Water supply forecasting
“As the study continues we hope to work closely with the municipalities, both to analyze historic water and weather data and to conduct water utilization studies,” Knight said.
The line established by Rose et al, used to estimate the recharge elevation, is a regional line for isotopes. “As the mountain has its own weather patterns, we are investigating the possibility of creating a hydrogen oxygen isotope line just for Mt. Shasta that would be more exact,”?said Unkefer. “It is important to know the actual recharge areas and residence time for our municipal springs so we can forecast water supply based on weather patterns. Linking precipitation to changes in spring discharge will help with forecasting. For example, if we have a number of big drought years then we can forecast when our supplies will be affected.”
Unkefer noted that forecasting is important for human use, but also for our aquatic neighbors. “If we are doing a major fish recovery project and we have a low water year, we’ll know how the springs will be affected both annually and interannually and thus how to manage the water supply for different beneficial uses,” she said.
The study also hopes to work with willing private landowners to sample and analyze springs waters on private property.
“In 2010 we plan to hone in on the spring vulnerability index to determine what criteria could affect springs in their recharge areas,”?Unkefer said. “Possible criteria include development, land use practices within the recharge area that could potentially affect runoff and recharge of the springs, and climate change.”
When asked about the field work portion of the project Unkefer spoke of long days spent, sometimes bushwhacking, with a Global Positioning System unit and a United States Geological Survey map trying to find the springs with only a little dot indicating there was a spring. “While I had frustrating moments trying to locate some springs, it was tremendously rewarding to find them,”?she said. “There is something wondrous about going up to a spring just popping out of the ground. Going to beautiful locations where water is just gushing out of the ground is a nice part of my job.”
The 33-page report complete with pictures, charts and graphs can be read at www.protectourwaters.org/science.htm.