Mount Shasta's Headwaters - Where does the water go?
Every day, people come to Mount Shasta City Park armed with gallon jugs – sometimes one or two, sometimes a dozen. They come to collect water from Big Springs, better known as The Headwaters, where hand-numbingly cold water rushes from the ground, through moss-covered rocks into a clear pool below.
“It’s a constant use,” said Mount Shasta Recreation and Parks District Administrator Mike Rodriguez. “Some days it’s five people, sometimes it’s ten. There are lots of regulars.”
Margaret Kunzler of Big Springs visits once every few weeks to get her drinking water from the revered spring. “I’ve even started to cook with it. I love the water so much, I just prefer it to our well water,” she said.
According to a 2009 study commissioned by California Trout, water bubbling from Big Springs – from an aquifer of the same name – fell high on the slopes of Mt. Shasta more than 50 years ago.
This is the same aquifer which Crystal Geyser proposes to tap for its juice manufacturing facility on Ski Village Drive. The company has private wells and water rights, a concept that alarms some in the community who are worried about possible over-extraction and damage to the aquifer.
Crystal Geyser’s proposed use of the prized water and recent drought conditions have increased the urgency to learn more about Mt. Shasta as a water source, said California Trout’s Conservation Director Curtis Knight, since it is vital to the entire state of California.
Cal Trout recently installed a gauge near Big Springs to measure stream flow and temperature. The measurements complement results of the 2009 study, though more studies are needed to paint an accurate picture of the area’s complex hydrology, Knight said.
Where the water goes
Whether as rainfall, snowmelt or glacial meltwater, water flowing from Big Springs spent decades filtering through layers of volcanic rock to emerge half a century later.
From the Headwaters, the springwater meanders through the park where a few other small streams converge into what’s known as Spring Creek. The water goes under Interstate 5 near the park and under Lassen Lane before flowing to the Mt. Shasta Fish Hatchery. From there it combines with Wagon Creek and pours into Lake Siskiyou. It then flows over Box Canyon Dam, creating hydroelectricity, and to the Sacramento River, where it ultimately ends up at Shasta Lake.
Shasta Lake is the largest reservoir in the state, said David Rizzardo, the Department of Water Resources’ Chief of snow surveys and water supply forecasting. It has a capacity of more than 4.5 million acre-feet, and is also fed by the Pit and McCloud rivers, as well as Squaw Creek and numerous other minor creeks and streams.
The reservoir accounts for about 17 percent of the state’s total water storage capacity, according to the US Bureau of Reclamation, which manages the water to be used for municipal water supplies, irrigation, flood control, hydropower generation and for fish and wildlife.
The Upper Sacramento River (above Shasta Lake) accounts for about 15 percent of the total annual inflow to Shasta Lake, said Rizzardo. The McCloud River accounts for 20 percent; the Pit River, including Squaw Creek accounts for 52 percent; and about 13 percent comes from other creeks and direct inflow to the lake.
The water stored there is part of the federally-run Central Valley Project, Rizzardo explained.
“CVP water makes its way to the Sacramento-San Joaquin Delta via the Sacramento River. From here, fresh water is pumped from the Delta and into a series of canals – such as the Delta-Mendota Canal (not the CA Aqueduct, that is water from the State water project). Various irrigation districts, water associations, etc. along the entire route (including north of the Delta in the Sacramento Valley) have water rights to take CVP water and use it for irrigation for crops,” Rizzardo said. “With the drought, many of these allocations are at zero this year.”
Cities use the water for municipal water supply – the water that comes out of your tap, said Rizzardo.
“Of course in Mount Shasta City you get your water from the source! But cities within the valley and elsewhere have water rights to supply their domestic/municipal drinking water." Some of that water is also used for industry, Rizzardo said.
Shasta Dam also provides flood protection for the Sacramento Valley, and the water is required as habitat for fish and wildlife.
In December of 2013, Cal Trout established a gauge downstream from the Headwaters to develop a baseline of flow and temperature conditions, Knight said.
Certified hydrologist Jim Fitzgerald has been monitoring the gauge since it was installed on Dec. 7, 2013.
Over the past three months, the gauge has revealed that the current flow of the creek is about 19 cubic feet per second and the average temperature is 45 degrees Fahrenheit.
One cubic foot per second of water equals approximately 646,000 gallons per day, Knight said. Mt. Shasta Big Springs therefore produces 19 cubic feet per second, which amounts to the spring producing approximately 12,274,000 gallons per day.
There are fluctuations in the stream’s output, Knight pointed out, from high flows of over 20 cfs to 15 cfs. The temperature of the water hovers around 45 degrees, with small fluctuations of about half a degree daily.
The reasons for these fluctuations are unknown, Knight said, but continued monitoring will help hydrologists learn more.
About the study
The Mt. Shasta Springs Study was conducted by Aqua Terra Consulting and ran from 2007 to 2009.
The study included taking water samples from 22 springs on Mt. Shasta at high, middle and low elevations in each of the three watersheds (Shasta, Upper Sacramento and McCloud).
Why is our water special?
Mt. Shasta is the largest Cascade stratovolcano with a volume of 120 cubic miles. Overlapping fractured volcanic geology and lava tubes are repositories for water.
The mountain acts like a giant sponge, according to the report. Rainfall, snowmelt and glacial meltwater filters through layers of volcanic rock and come out as hundreds of springs around Mt. Shasta.
There are a few perennial streams flowing off the sides of the mountain, but most of the water is absorbed into the ground, the summary states. This groundwater flows to the surface as springs, feeds the base flow of the rivers, and is pumped by private and municipal wells.
Residence and recharge
The study found that water flowing out of Mt. Shasta Big Springs is more than 50 years old.
Age of the water, also known as residence time, is defined as how long it takes for water that fell as rain or snow on the mountain to percolate into the ground and emerge as a spring.
Water younger than 50 years old is age dated through analysis of the tritium isotope. Prior to above ground nuclear testing there were three to four kilograms of the tritium isotope on the earth’s surface, according to the summary.
“In the late 1950s and early ’60s, nuclear testing... increased tritium by 2 to 3 orders of magnitude,” the report states.
When water flows underground, it retains the tritium concentration from the atmosphere around it. Hydrologists can then measure concentrations of the isotope at the point water emerges from a spring to determine its age.
Water flowing from Big Springs has absolutely no tritium present, meaning that it went underground more than 50 years ago, said Knight.
Carrick Spring in Weed is also more than 50 years old. Muir Springs was dated as 14 years old; Shasta North Spring as 26 years old; and Shasta East Spring as 44 years old.
Recharge elevation is determined by analyzing stable hydrogen and oxygen isotopes in the water, according to the report.
As clouds release their precipitation, the heavier isotopes fall out at lower elevations leaving lighter isotopes to fall at higher elevations, according to the summary.
The distance between the elevation where the rain or snow fell and the elevation a spring discharges could be considered the recharge area of the spring. Of the 22 springs sampled for hydrogen and oxygen isotopes, data indicates the recharge elevation for almost all of them is above 5,200 feet.
The study found that water emerging at the City Park’s Headwaters fell above 8,000 feet on Mt. Shasta’s slopes.
For more information
For more details about the study, go to caltrout.org/mountshastasprings/