Despite regular rainstorms in southeast New Mexico, the water is probably not doing much to recharge the Ogalalla Aquifer.
According to Mike Johnson, hydrology bureau chief with the New Mexico Office of the State Engineer, whether or not rain recharges the aquifer is a complicated question due to the fact that the OSE does not measure recharge directly.
“It’s difficult to measure, but we do measure water level in wells, and there’s a lot of wells in the High Plains (Ogalalla) Aquifer, and our office cooperates with the United States Geological Survey, a federal agency to measure water level in those wells. Those give you an idea of how much water is in the aquifer, and if water levels are going up or down or staying steady.”
He said it is uncommon for wells in the Ogalalla Aquifer to be recharged by rain, although it isn’t unheard of.
“It depends on the aquifer,” he said. “Some aquifers are much more responsive to events like that, and you will see the water levels come up in response to rain and/or runoff, stream flow, of course you don’t have any streams in the High Plains Aquifer.”
He used the example of a well north of Hobbs to show that the water level in the Ogalalla Aquifer is steadily dropping with little influence from the weather. From the early 1940s to 2015 the well in question dropped from 3,640 feet (depth to water from the surface) to close to 3,570 feet.
“What you see is a pretty steady decline in water level from the 1940s to today with a few blips up and down here and there, but you don’t really see necessarily any kind of departure due to changes in weather. There’s too much of a lag time,” he said. “The pattern is more dominated by the pumping here than it is by changes in recharge. Based on this, I wouldn’t expect you to see any kind of noticeable change due to a wetter year versus a normal or dry year.”
Despite the drop in water level of the well, it is not necessarily indicative of the well being near the end of its life.
“The 3,570 level is not necessarily the bottom of the aquifer,” he said. “It means that the High Plains Aquifer is being depleted of water, which we’ve known. Obviously since the 1940s it’s been pretty clear that water levels are going down.”
He said the well was similar to most wells in the aquifer, particularly those in agricultural regions where constant irrigation use has drastically lowered water levels.
“With irrigated agriculture, this is fairly typical,” he said.
The Ogalalla Aquifer is spread across New Mexico, Texas, Oklahoma, Kansas, Colorado, South Dakota, Nebraska and Wyoming. According to www.waterencyclopedia.com, the aquifer is in a state of overdraft, meaning that water is being used faster than it is being replenished.
Replenishment comes from rainfall, but how fast the aquifer is replenished is unclear.
Charlie Benton can be reached at 575-391-5434 or by email.