Where’s the water?
While the prospect of another public golf course at Gray’s Crossing may have golfers’ mouths watering, some residents along nearby Prosser Dam Road are worried the water pumped out of the ground to keep the turf green will leave them high and dry.
Rusty Pauli, a resident on Prosser Dam Road, said he is concerned about he amount of water the golf course will be drawing from the underlying aquifer.
“My water comes from a well and the water for the golf course is coming from a well, so the issue becomes: How much water is available?” he said.
Pauli said that he has spoken with engineers from the Truckee Donner Public Utility Distric, which has plans to drill up to three new wells in the Old Greenwood-Gray’s Crossing area, and they have assured him that any water taken from that area will come from deep sources that will not affect the more shallow aquifer that Prosser Dam Road residents tap into.
“My concern is that they will deplete the water supply,” Pauli said. “But from what I understand and have been told, there’s a huge volume of water down there.”
One of Pauli’s neighbors on Prosser Dam Road, Janna Caughron, is more skeptical of the district’s claims.
“I can’t imagine that there wouldn’t be an effect if they start drawing down the aquifer,” Caughron said. “Then the shallower [water] is going to start draining down into the bottom.
“They’ll tell you that there are clay lenses and all that kind of stuff, but if that’s true, then how is all that water down there?”
Both Caughron and Pauli remember the drought during the 1980s that saw many residential wells along Prosser Dam Road dry up and the subsequent need for deeper drilling. Caughron said he worries the district’s plans to stick more straws into the aquifer will backfire someday, leaving the homeowners on Prosser Dam Road with the need to pay for the extension of water lines to their homes ” an expensive proposition.
“You can pay these engineers to say whatever you want, and the PUD has got an engineer to say that there’s an infinite supply of water,” she said. “Well, where in the West has there ever been an infinite supply of water?
“Are we going to go like the Midwest and end up with the Ogallala aquifer? That was an aquifer that they said would last for millions of years, and it’s been depleted.”
The Martis Valley Aquifer is big, according to Ed Taylor, Truckee Donner Public Utility District water utility director. It extends from Northstar in the south to Hobart Mills in the north, and underlies parts of Tahoe Donner in the west to Boca Reservoir in the east.
The aquifer supplies water for the utility district and residents in the area, who draw their well water from the source.
“The basin that we’re tapping into was at one time a miniature Lake Tahoe,” Taylor said. “It varies in depth from 1,300 to 1,100 feet deep, and over the last few million years it has been glaciated in ” in other words it’s been filled with sand and gravel …”
According to a recent study entitled “Ground Water Availability in the Martis Valley Ground Water Basin,” completed in 2001 by Nimbus Engineers of Reno, Nev., for the utility district, the Martis Valley Aquifer is composed of permeable layers of sand and gravel varying in depth from around 1,100 – 1,300 feet, with a impermeable Sierra granite beneath it. The aquifer contains approximately 484,000 acre-feet of water and is divided in places by impermeable clay aquitards, which prevent water from moving vertically within the aquifer.
To put that into perspective, one acre-foot of water is equivalent to 326,000 gallons ” enough water to meet the needs of 350 average Truckee homes during the summertime, according to Taylor.
Taylor said that the utility district pumps approximately 35 acre-feet of water from the Martis Valley Aquifer during a peak day to cover the needs of all users of the district’s water system, though during the wintertime that number drops of significantly.
In total, the town of Truckee currently uses approximately 7,000 acre-feet of Martis Valley Aquifer water annually, with developments in Placer County pumping out an additional 1,700 acre-feet each year.
And while humans are pumping water out of the aquifer, Mother Nature is pouring water back in via snowmelt, streams, precipitation and other recharge mechanisms at a rate of 29,165 AF per year, according to the Nimbus report.
Crunching the numbers, the hydrologists at Nimbus Engineers concluded that 24,700 acre-feet of water can be drawn from the Martis Valley Aquifer annually without changing the volume of ground water storage ” an amount known as the “sustainable yield” of the aquifer.
Utility district engineers take this data and compare it to worst-case scenarios for development in Truckee and Placer County in developing their Water Master Plan.
“We take, on every parcel, the worst-case scenario ” what could be built there and how much water could they use,” Taylor said. “At total buildout in Truckee … we’re looking in the vicinity of 13,000 to 14,000 acre-feet of water in a given year that would be extracted from the basin.
“We have to add to that what could happen in Placer County … And they’re talking an extra 6,000 acre-feet on the Martis side. So we’re looking at 20,000 acre-feet of water [annually], and that’s if everything is built today … So we’re well underneath the sustainable yield of the basin.”
While the Nimbus report seems to indicate that the PUD ” which drills wells deep into the lower portions of the aquifer ” will always have plenty of water available, it does not address the effect increased water consumption will have on domestic wells such as those along Prosser Dam Road.
“There are three separate layers or aquifers out there, and we pull water only from the two bottom ones,” Taylor said of the utility district’s wells. “We don’t touch the upper aquifer ” we stay away from it. That way we don’t impact surface features and we don’t impact localized wells or anything like that.”
The district seals off the top 300 feet of its wells so as not to draw water away from residential wells and surface water features such as lakes and streams, Taylor said.
“Typically, residential wells are drilled to 150 to 200 feet or somewhere in that vicinity,” he said. “We’re [drilling] down to 1,200 to 1,300 feet, and we seal off the first 300 feet. We as a district don’t want the surface water. Your normal domestic wells are that localized surface water ” that’s where they get their source.”
When looking for new well sites, engineers from the utility district drill test holes and look for sites that have both abundant water quantity and excellent water quality.
“Can we treat [poor quality] water to become drinking water? Yes. But it becomes expensive,” Taylor said. “So we’re trying to avoid the water quality complications so we as a district don’t go into water treatment.”
Water treatment, to get rid of compounds like arsenic, manganese and iron, which are found in some ground water sources in this area, is a prohibitively expensive proposition that the PUD does not want to get into, Taylor said.
Currently, all drinking water within the district is pulled straight out of the ground and treated only with chlorine, which is required by California law.
Microbial contaminants such as viruses and bacteria that may be present in surface water throughout the district are completely filtered out when the water percolates through the volcanic sediment that makes up the Martis Valley Basin, according to the district’s 2004 Water Quality Report. Thus the district has been able to meet all drinking water standards set forth by the California Department of Health Services.
The three well sites proposed for the Old Greenwood-Gray’s Crossing area would be able to pump approximately 6 million gallons of water per day, and would tie in to the district’s entire water distribution system, according to Taylor.
Currently the district has plans to drill one well in Old Greenwood this year, with an aim of having it online by late fall or early spring of 2006. The other two could follow over the next two years if development in Truckee warrants their construction.
Fire flow requirements and a requirement that the district be able to meet their peak water need without their largest source mean that the district must continually enhance its water supply as the town grows.
Instead of oversizing the system to be able to pump that much water at one time, the district has built storage tanks that keep reserves for domestic consumption as well as fire storage and operates a real-time computer system that keeps those tanks within a specified range.
What the future will hold for the Town of Truckee and the Martis Valley Aquifer is, of course, up in the air ” or down in the ground as the case may be, but Taylor and the PUD in general stays out of the political decisions that affect how much water will eventually be needed.
“As a district, we provide a service,” Taylor said. “The political end of what can be built and how it can be built, that’s not our concern. Our concern is providing water to our customers. And what we’re saying right now with all our master plans and all of the studies that we’ve done is that we can provide that water even under the worst-case development situation.”
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