The big storms are over for now, but unless the Hualapai Basin magically refills soon – and it won’t barring a flood of biblical proportions – water will continue to vex public officials and be a source of worry for residents.
Finding ways to divert and store the next downpour was one of many topics city officials, the Mohave County Board of Supervisors and water and geology experts discussed in depth at a water workshop Jan 13.
Local geologist Luis Vega started off the meeting by describing the basic geology of the Hualapai Basin and how the aquifers under north Kingman and Red Lake play a critical part in Kingman’s water supply. Depending on the population and agricultural growth, the picture looks something like this:
Provided Kingman stops growing right now, with the aquifer’s current level, there is 216 years of water left. That includes a yearly city usage rate of 8,000 acre-feet and yearly farming usage rate of 25,000 acre-feet. The numbers change to 115 years of water left with an annual three-percent population growth and 75 years with both population and agriculture increases.
Of course, the data Vega depended on was produced in 2011, a few years before a number of large scale farming operations broke dirt and planted crops in Mohave County.
“A simple way to look at it is you got a bucket of water and a straw taking water out of this bucket nd you have a little trickle going into the bucket.,” Vega said. “Eventually the straw taking the water out is going to win over that little trickle going into the bucket.”
Water Quality an Issue
There’s still plenty of water in the aquifer, but not all of it is readily usable. There’s fresh water near the surface, but the water turns to brackish salt water at the deeper levels.
“You may have heard people say that there is a lot more water in these basins than what Arizona Department of Water Resources says there is,” he said. “The question is, is it good water?”
The Red Lake subbasin holds the largest inland salt deposit in the U.S. at nearly three miles long and a mile deep. All the water in contact with that deposit is salt water and the deeper it goes, the higher the salinity. There are also contaminants such as arsenic in the deeper levels.
“(The water) is not usable unless you treat it,” Vega said.
Vega said one of the biggest problems is that Kingman doesn’t have surface water, such as a river, to replenish the aquifer.
“What’s in the ground is there,” he said.
Vega described anomalies known as cones of depression that are formed when a well is drilled and that monitoring them is critical to keeping an eye on the water levels.
“Where this is important is the larger wells that are pumping a lot of water…you want to know what impact they’re having on the water table,” he said. “If you don’t’ have a monitor well close by, it may be years before you see the damage to the water table.”
According to Vega’s data, the water table has dropped 80 feet in the last 54 years. More water is being pumped out (32,000 acre-feet per year) than going back in (10,000 acre-feet).
Vega laid out possible courses of action for Hualapai Valley starting with either an Irrigation Non-Expansion Area or an Active Management Area, both of which involve slowing or stopping low priority, high volume water uses (agriculture). Another step would involve finding ways to recharge the aquifer – such as diverting rain runoff into recharge ponds. The state already has shot down the county’s request for the former, commonly referred to as an INA.
Vega said rainwater that makes its way to the desert basins near the airport and Red Lake either evaporates or soaks into the caliche, preventing the water from infiltrating into the basin.
“If there was some way to get that water into the aquifer, it would increase that trickle going into the bucket,” Vega said.
He suggested the county implement conservation measures, but even those couldn’t make up for the loss. As a last ditch measure, he suggested Arizona foot the bill for a California desalination plant for its own water uses while Arizona would use Colorado River water normally sent to California.
“There other ideas like that that need to be addressed,” he said. “We should be addressing that now.”
One of Vega’s simplest suggestions is for those already owning wells to install sounding tubes.
“It doesn’t cost very much, maybe $200,” he said. “It’s just a piece of PVC pipe put down alongside the (drop pipe) where you can put down a low-tech instrument to measure the water.”
Nick Hont, civil engineer for Mohave County Development Services Department, reiterated (in more exact engineering terms) Vega’s presentation, and said a larger study is needed to determine future water usage.
He said the most recent United States Geological Service studies were based on data from 2011, before agriculture began in Kingman and that the new farms have drastically modified and increased the water withdrawal.
Hont laid out plans for a possible $450,000, three-year impact study where USGS, Mohave County and City of Kingman would split the bill.
The survey would accurately establish water withdrawal effects with models to predict impact on Kingman wells and anticipated time frames for changes of aquifer water levels.
Those models would also be used to predict the impact of proposed mitigating measures of water injection into the recharge basins and different models would be developed by county and city officials.
Hont is confident the USGS will give the city and county the best bang for the bucks. He said he’s worked with private consultants who could charge twice as much.
“It’s going to be a three-year program to get an accurate model,” he said. “We’re getting the best scientists. This is the United States government.”
State is Engaged
“Let’s start doing it,” he added. “It’s not too late.”
Environmental attorney Patrick Cunningham was another guest speaker and assured the audience that the state is paying attention.
He said Gov. Doug Ducey has studied Mohave and La Paz water issues and wants to work with state agencies and local s to create solutions that can be implemented.
Cunningham said state Rep. Regina Cobb, R-Kingman, has introduced a bill and is working on another to expedite the process for Mohave County.
“Monitoring our aquifers and seeing how healthy (they are) is absolutely required,” Cunningham said.
There were a significant number of statistics and other information presented during the workshop. The video can be viewed at http://www.cityofkingman.gov/IWantTo/ViewVideos.aspx