The onset of moderate temperatures and the end of the growing season have distracted Iowans from the unabated continuation of the drought of 2012.
“It’s almost like people get drought fatigue. The need for water seems less urgent after the growing season, and the drought does not seem like a big deal when the weather is cooler,” said Tim Hall, bureau chief of the Department of Natural Resources Geological and Water Survey.
But, masked by glorious fall colors and ideal harvest weather, Iowa’s rainfall deficit continues to mount in the first week of the year’s 10th month.
“We are concerned. We are watching the numbers. But in the end, like everyone else, we have to depend on what comes out of the sky,” said Hall, who coordinates the Governor’s Drought Task Force.
What’s fallen lately? During the past two weeks, the statewide rainfall average has been a paltry 0.04 inch.
Not enough even to settle the dust, let alone replenish depleted subsoil moisture, recharge wells or raise the perilously low levels of rivers, lakes and ponds, according to Hall.
During the past week, the portion of Iowa in extreme drought increased from 65.8 percent to 75.3 percent, according to the U.S. Drought Monitor map released Thursday
Average statewide precipitation through Sept. 30 totaled 20.57 inches, more than 9 inches below the normal 29.69 inches for the first nine months of the year, according to State Climatologist Harry Hillaker.
Thus far, 2012 has been the eighth driest in 140 years of record keeping, he said.
Nevertheless, Hillaker said Iowa will likely top the 21.65 inch statewide average during the last severe drought in 1988, though it will come nowhere near its normal annual rainfall of 35.27 inches.
Soil moisture declined again this week, falling to 93 percent short or very short in topsoil and to 96 percent short or very short at the subsoil level.
“Yes, farmers should be nervous about next year’s crop,” said Iowa State University Extension Climatologist Elwynn Taylor.
Fully recharged soil would hold about 10 inches of crop-available moisture, which compares with 3 to 4 inches banked in most parts of the state, he said.
With frozen soil likely in December, “We will soon run out of time to build it back up,” he said.
Taylor said 2012 was the third straight year of below-trend crop yields and that next year will likely be the fourth.
While the soil grows ever drier, Iowa rivers and streams are trending toward record low flows.
Among Eastern Iowa rivers registering their lowest flows at particular measuring stations are the Iowa below the Coralville dam, the Wapsipinicon near Tripoli and the Volga at Fayette. Eastern Iowa gauges with their second-lowest recorded flows include the Wapsipinicon at Anamosa and Muddy Creek at Coralville. Gauges with their third-lowest recorded flows include Clear Creek near Oxford, the Turkey River at both Eldorado and Elkader and the Upper Iowa at Bluffton.
The Cedar River at Cedar Rapids stood Friday at 2.72 feet, discharging 479 cubic feet per second — a flow that ranks in the lowest 2.5 percent of early October flows at the 110-year-old gauge.
“We are down to base flow — basically seepage from groundwater — and many smaller tributaries have dried up,” Hall said.
A severe winter with thick ice and snow could deplete oxygen and kill fish, especially in ponds and smaller lakes with shrunken water volumes, said Mike Steuck, the DNR’s northeast Iowa fisheries supervisor.
“The less water volume, the less oxygen available to fish,” he said
Steuck said he’s less worried about fish in streams, where even negligible current should help maintain adequate oxygen levels.
“We need to gain water this fall and hope for a mild winter,” he said, adding that the DNR has no budget for emergency aeration to alleviate imminent fish kills.
Low stream flows and low subsoil moisture are both caused by falling water tables, the same condition that is causing wells to go dry, Hall said.
Three emergency wells have recently been drilled in the Carroll-Glidden area of western Iowa to provide drinking water supplies for municipal or rural water systems, he said.
“Demand for water will increase again in the spring. If there is no improvement in the water table, we will find ourselves getting pinched for drinking water,” Hall said.