With more than 1,200 square miles of land area, U.S. Army Yuma Proving Ground (YPG) is the fourth-largest installation in the Department of Defense in terms of land area.
Testers see the proving ground as a natural laboratory, and thus have a vested interest in good environmental stewardship.
Home to a wide variety of animals, including the Sonoran pronghorn and one of the largest and most genetically diverse populations of bighorn sheep in Arizona, YPG helps sustain the creatures with 25 wildlife water drinkers situated across its mountains and desert range.
“These waters are some of the most phenomenal things we have for wildlife,” said Daniel Steward, wildlife biologist. “It allows animals to spread across the range and get full use of the habitat.”
The drinkers are a stabilizing presence in one of the nation’s driest desert regions, with mechanical apparatus to keep a steady supply of water available for wildlife. Mule deer, bobcats, coyotes, multiple bird species, even bees benefit from their presence.
“We have dry years and not so dry years,” said Steward. “One of the values of having adequate water storage out here is having a buffer in dry years—they give resiliency to our ecosystem.”
The drinkers run the gamut in age, with some concrete ones dating back to the 1950s.
“A lot of these drinkers are like granddad’s axe: it might be on its second head and fifth handle,” said Steward. “Some of these drinkers have had different troughs and tanks over the years. We’re always swapping components when something breaks.”
Wildlife officials are meticulous about keeping the drinkers a viable and perennial presence on the range.
“It’s important to keep them in the same location because wildlife get used to them and they’re an important feature of the habitat,” said Steward. “We want to keep them up and going for the long term.”
More recent underground storage tanks for the drinkers such as one that was recently inspected on YPG’s Cibola Range are made of PVC and filled by water runoff from the desert’s rare rain events. A steady rain event can fill the 10,000 gallon tank, and they are situated with care near washes that will run, but not large ones that will run so violently that the tank fills with sediment instead of water. Experience has shown that rain water has a lower saline level than water from local wells, which means less sediment buildup to foul water apparatus’ moving surfaces.
The PVC is also hardier than the vinyl liner inside an adjacent above-ground rain tank constructed decades ago, which tends to degrade when not continuously filled with water. This older tank has a persistent leak now, but wildlife officials have no plans to remove it.
“Even though this tank has a leak in it and isn’t what we want to depend on, it has water in it, and we won’t ever let water go to waste,” said Steward. “We can pump the water out of this rain tank and put it in our better system, because we haven’t had very much rain this year.”
An important innovation for the drinkers in recent years was the addition of solar-powered sensors to continuously monitor water levels.
“We were already using the existing sensors on our wash monitor systems, which range control uses to see the depths of the various washes across the range when they start running,” said Ryan Ingham, electronic technician with YPG’s meteorology team. “The pressure transducer gives a pressure reading that we convert to inches of water.”
Topographical features surrounding many of these drinkers obstruct radio signal that sends the data out, requiring some clever workarounds.
“Most of the drinkers sit inside a terrain bowl or at the bottom of a canyon,” said Ingham. “We had to create relays to bounce the signals to our existing system.”
The sensors spare personnel from having to regularly travel to extremely remote and rugged parts of the range to monitor water levels, and allow for a rapid response if there is a sudden and catastrophic loss of water in one of the drinkers. The instrumentation accurately measures the daily water loss rate, which changes with the seasons and soaring desert temperatures.
“That allows us to continuously update forecast models of the consumption rate of the animals, particularly deer and bighorn sheep,” said John Hervert, terrestrial wildlife program manager with the Arizona Game and Fish Department (AZGFD). “It really helps us fine-tune our estimates.”
“Our meteorologists can take historic weather data and come up with a trend,” added Ingham. “The longer these monitoring systems are in place, the more data we’ll have and the better picture of what the actual burn rate is.”
Though the proving ground is the nation’s largest artillery tester, it also encompasses the best preserved and protected Sonoran desert landscape in the American Southwest. The healthy proliferation of a diversity of desert creatures under careful stewardship is, undoubtedly, one of the positive results of this.
“The partnership that Arizona Game and Fish enjoys with Yuma Proving Ground is very helpful to our agency,” said Hervert.