3/26/2010 9:56:00 PM Rainwater harvesting could be huge factor in safe yield efforts
Joanna Dodder/The Daily Courier Flush with spring runoff, Granite Creek spreads out across a sand-and-gravel streambed near Highway 89A. This is a perfect area to recharge rainwater into the aquifer, according to Civiltec experts.
Raymond Buettner/Courtesy Civiltec President Rick Shroads and Project Engineer Doug McMillan check out the Granite Creek area with design plans and pipe materials for the Upper Verde Coalition’s pilot study on how to recharge more rainwater into the aquifer.
The Prescott region loses more than 98 percent of its precipitation to evapotranspiration - a combination of evaporation and plant transpiration.
That adds up to more than 407,000 acre-feet of water each year - more than 17 times what people living in the Prescott Active Management Area (AMA) use.
A Prescott engineering firm called Civiltec has calculated that if the AMA could capture annual rainfall in just a three-by-six-mile area, it could eliminate the AMA's annual groundwater overdraft of about 11,300 acre-feet (not including 4,150 af of basin outflow) so the AMA could reach the state-mandated "safe yield" status and stop depleting its groundwater supply.
"It's sustainable water, it's renewable water," engineer Doug McMillan said of rainwater harvesting. He has created a PowerPoint presentation about the issue and shown it to dozens of local leaders over the past year or so.
"I think it's a very valid approach we need to pursue," said John Munderloh, Prescott Valley's water resources manager, who has viewed the presentation. "This is a water supply not examined by and large by the scientific community."
It is becoming a more common topic locally, however, especially with the help of Civiltec and the Upper Verde River Watershed Protection Coalition, made up of representatives from local municipalities and the county.
Led by Civiltec President Rick Shroads, the company is working on an Upper Verde Coalition pilot project to capture rainwater that falls on impermeable soils in the Prescott area and directing that water toward areas with more permeable soils so it can trickle into the depleted aquifer.
A large portion of the Prescott AMA has such impermeable soils.
A perfect project site would be the Pronghorn subdivision north of Prescott Valley, where clay soils don't allow rainwater to seep into the ground, McMillan said. It already has channels that could direct rainwater to a catchment basin, then pipes could take the water on over to the nearby Granite Creek floodplain.
"This is the window to the aquifer," said McMillan, pointing to an image of Granite Creek north of Prescott. Its wide floodplain consists of highly permeable gravel and sand that is hundreds of feet deep.
The Upper Verde Coalition also has discussed the importance of protecting prime recharge areas such as the areas around the Granite Creek floodplain. Large swaths of the currently open floodplain are slated for future development.
Arizona has one of the highest rates of evapotranspiration in the country, McMillan said.
Man-made lakes and unnaturally dense vegetation also reduce nature's ability to recharge the aquifer.
For example, with the construction of the Willow and Watson lake dams on top of granite, the AMA started losing another 2,400 af annually to evaporation, McMillan estimated.
And unnaturally dense chaparral is responsible for about 40 percent of the local transpiration (release of water from plant leaves), he estimated.
Prescott National Forest officials have been working to reduce the density of large swaths of chaparral in the Prescott Basin for a decade.
Rainwater harvest laws
Another way to increase groundwater recharge is through perforated underground lines along roads where water already collects, McMillan said.
Australia is a leader in this field. India and Germany also have taken major steps toward rainwater harvesting.
"This is a big issue overseas," McMillan said.
Several regions in the Southwest U.S. have rainwater harvesting laws.
The Tucson City Council approved the nation's first municipal rainwater harvesting ordinance for commercial projects in 2008. New businesses must supply half their landscaping water from harvested rainwater beginning June 1.
The council also voted to require a plumbing hookup in new homes so homeowners can choose to use grey water in their yards.
The New Mexico counties of Santa Fe and Bernalillo have required commercial as well as residential rainwater harvesting since 2008. Homes larger than 2,500 square feet must have rainwater cisterns, and businesses must collect roof drainage into cisterns.
Arizonans can get a 25 percent or $1,000 tax credit (whichever is smaller) for installing systems that harvest grey water.
Prescott offers several conservation incentives on water bills, including a $500 credit for the installation of a rainwater catchment system.
At the same time, Prescott has spent more than $35 million on its plan to import a maximum of 8,068 acre-feet of groundwater annually from the neighboring Big Chino Aquifer.
The Upper Verde Coalition has discussed the long-term possibility of using the rainwater harvesting pilot program to develop construction codes.
Posted: Sunday, July 25, 2010
Article comment by:
Peter Hydrographer
I have been involved in Water Resources and Water Research in Western Australia for almost 40 years. Water harvesting using "sealed or impermeable catchment areas" is an integral solution for the viability of communities that are situated in areas with limited rainfall. Without methods for capture, storage and recharge of as much rainfall as possible these communities would not survive. Civiltec's proposals need serious consideration, and their ideas should be incorporated in the effort to attain a sustainable water regime. Every drop counts!
Posted: Sunday, March 28, 2010
Article comment by:
Tom Atkins
Thank you Creagan. My rain catchment system is several months over two years old (it just seems like 10, I have blabbed about it so much!) and has made a huge difference in the amount of water that I use from the Little Chino Sub basin / Aquifer. My average water consumption before I installed the rain water harvesting / distribution system was ~5256 gallons per month almost 90 gallons per person per day (still lower than the 154 local average). After installation, consumption dropped to an average of ~1253 gallons per month and ~21 gallons per person per day in the household. Along with the rain catchment system, I thought that I should go all out, and installed an aggressive 1 gallon per flush toilet, fixed some dripping faucets, and finally purchased a water-sipping clothes washing machine. The main item though is the rain catchment system. I am slowly converting my landscape to local native plants. I am afraid that lawns are much too greedy and only belong where there is plenty of natural surface water. The fun part is, my system is filled to capacity and I just finished planting my potted flowers and bulbs (soil amended with water retaining gel), I think that if I am careful there will plenty of water to last until the summer monsoons! Then, hopefully, everything will fill up for the fall and be empty by the winter freezes. We are lucky to have a double rainy season! I still have the grey water card to play. Call me crazy, but it is a lot of fun, and a challenge to try to figure out the consumption rate. I am very aware of the possibility of rain. I have heard at a number of public meetings that “it is too late to conserve our water to the point of sustainability” therefore... “we must pump the Big Chino” (and dry up the Upper Verde River). They don’t mention the last part in parentheses! I figure that we can become sustainable if we use less than 35 gallons per person per day! For the last two years our household is using less than that. Our Active Management Area could, with a lot of planning, effort, and leadership become sustainable without depleting our aquifer. The problem, the major sleeping monster, it requires us to consider population growth restrictions. “I am sorry folks, the Prescott Active Management Area is full. You will have to wait until someone moves or dies before moving in!” Talk about a can of worms! Conservation to sustainability is fruitless unless combined with a stable population. If everyone conserved to a sustainable water use rate, and the population doubled... Guess what, we are back where we started and no matter what, and we are then completely out of luck. Thirty five gallons a day is quite comfortable, but try 18! Things get pretty dodgy with that daily amount, sponge bath anyone? Composting toilets? You get the drift. We have to start making some very tough decisions about our water supply and our population growth. I am lucky, I am an old geezer and my own water molecules will be part of the water cycle by the time this reaches a crisis stage. I just think that the kids that we see playing around our wonderful town should have something left by the time they are my age. Please check out www.prescottslastoasis.com
Posted: Sunday, March 28, 2010
Article comment by:
to: Creagen McConnell
This has been common practice for decades - this just shows how far behind AZ is. We needed engineers to validate this? Yeesh!
Posted: Sunday, March 28, 2010
Article comment by:
Creagan McConnell
Civiltec and the City of Prescott deserve credit for bringing this conservation practice forward but let’s give credit where credit is due. Our very own local resident Tom Akins has been promoting and speaking on this subject to local community groups for years now. Under Mayor Wilson’s administration his ideas and practices were simply brushed aside. I would like to hear Mr. Akins take on this article how his own rain water catch system has been saving water at his home over the past ten years or so. I do look forward to the current administration adopting and implementing programs that will encourage better water conservation practices.
Posted: Saturday, March 27, 2010
Article comment by:
it is not ours to keep
Hate to rain on the parade but we don't own the rainwater. Once it accumulates into runoff it becomes surface water, which is owned by SRP. It does not matter whether runoff goes to a beneficial use or is wasted through evaporation, it is SRP's to waste. The collection or accumulation of rainwater for storage is only by SRP's permission. We can certainly spend a lot of money directing flows toward Granite Creek, but the moment runoff has a value assigned to it SRP is going to be wanting it from us. Tucson has an ordinance for commercial sites to be designed with the idea that runoff flows into landscaped areas. It does not involve large scale capture of runoff nor is Tucson located within SRP's surface water rights.
Posted: Saturday, March 27, 2010
Article comment by:
Roger Williams
I thought there was some kind of law that prohibited Prescott from capturing rain water during certain months - that it belonged to SRP or some other organization. Anybody know the truth of that?
Posted: Saturday, March 27, 2010
Article comment by:
Paul Davidson
What a fantastic idea. We stop continued development north of P.V., save what little is left of our antelope habitat, harvest rainwater to recharge our aquifer, and dramatically reduce our threat to the Verde River. Everyone wins. Now the question is, how long do we think about it before we act?
Posted: Saturday, March 27, 2010
Article comment by:
Tom Hahn
It's great to hear what we've been teaching at Ecosa for over ten years, and what others have been showing through research for decades, is now making its way into policy for the Prescott area and Upper Verde basin. We wholeheartedly support the proposition that we can meet our long-term, sustainable water needs through water conservation and various scales of rainwater harvesting and recharge, at a fraction of what the Big Chino project will cost. In addition, harvesting/recharge strategies would, at the same time, also reduce stormwater runoff, non-point source pollution of the creeks, and reduce flooding such as we've seen this winter.
Tom Hahn Assoc. Director Ecosa Institute www.ecosainstitute.org
Posted: Saturday, March 27, 2010
Article comment by:
Win Hjalmarson
Seems the AMA has entered the 20th century while caught up in the euphoria of abundant spring runoff. Managed ground water recharge in Arizona is old news. Its encouraging to hear that Prescott is taking their safe yield problem seriously but talk is cheap with a temporary supply of excess water. I've observed that Prescott is more interested in creating an image of plentiful water by keeping Watson and Willow Lakes full while ignoring recharge of the depleted aquifer. The braided sand and gravel channel of Granite Creek does seem a good place for managed recharge. The USGS has been studying mountain front recharge in the southwest for many years.
Posted: Saturday, March 27, 2010
Article comment by:
b b
Why can't we just learn to live with what Mother Nature has given us?
