Don't take aquifer for granted
The Jordan aquifer is Iowa’s most productive and widespread source of ground water. It provides high-quality drinking water for 300,000 Iowans. Many farmers and industries also draw from its depths.
Much good water remains in the aquifer but it is not an endless supply, state geologist Bob Libra warns. Levels have dropped significantly.
We should heed his warning. Demand is drawing down the aquifer and likely will only increase. And the deeper we have to go for the water, the poorer the quality.
Libra recently cited a study that found the Jordan’s water levels have declined by as much as 300 feet since humans began tapping it in the 1800s. Just at current withdrawal rates, the levels are expected to breach the state’s 1975 baseline within 20 years in parts of Linn and Webster counties, which, along with Polk, have used the aquifer the most for the longest time.
Two decades may seem like a long ways off. But the rate of withdrawal undoubtedly will increase. Ironically, the recent boom of ethanol plants and geothermal heating/cooling systems — players on the renewable energy stage — have helped accelerate the draw on the Jordan.
It takes three or more gallons of water to produce a gallon of ethanol at the average plant. That can mean several million gallons of water used daily, as much as used by a town of 5,000 people.
Geothermal systems are increasingly used in homes and, on a larger scale, in many schools. Although startup investment is greater than conventional methods, geothermal systems are highly efficient. However, a lot of ground water is needed to operate them. If the system “pumps and dumps” into streams and sewers instead of reinjecting the water into the aquifer or using a closed-loop process, underground water supplies can be affected.
The Jordan aquifer is vast, running from northeast Iowa toward the southwest under Linn County, where its depth reaches 1,200 feet, to nearly a half mile deep in south central Iowa. However, like all natural resources, we cannot afford to take the aquifer’s reserves for granted.
The amount of water being pumped out greatly exceeds that which is returning. And replenishing takes decades because the aquifer is so deep — rain water finds its way slowly through the rock structures into the pores where it is stored.
We’ve been warned. There’s no excuse for waiting to act until a crisis develops in our priceless aquifer. We’d like to see state officials and experts develop a plan of best practices and regulations that balances development interests with protections that sustain the Jordan.Sooner than later.