DES MOINES — Iowa received 3.98 inches of rain in July, slightly less than normal, according to the latest Water Summary Update.
Rainfall was above normal in the western and southern parts of the state, and below normal in central and northeastern areas. The continued lack of rainfall led to the expansion of drought conditions in Iowa, and the return of the extreme drought classification for the first time since April.
About 75 percent of the state is rated in some level of drought, with severe drought covering over one quarter of Iowa, and extreme drought covering almost 7 percent of Iowa. Since early July, drought conditions have improved across western and southern Iowa, but have deteriorated in east central and northeast parts of the state. The extreme drought designation covers the largest area of the state in nearly a year.
This dryness is reflected in decreasing streamflows in central and north central Iowa, and continued concern for shallow groundwater supplies in some areas of the state. The area of concern for shallow groundwater has shifted from northwest Iowa to north central Iowa.
“The rain that the state received in late July was needed, and where it came we have seen improvement in conditions. As we move through August we anticipate increased demand for water, and unless we see normal to above normal rainfall in the driest parts of the state, conditions could deteriorate,” said Tim Hall, DNR’s coordinator of hydrology resources. “The area of most concern, northwestern Iowa, has seen much needed rainfall, and conditions have improved there.”
Since the last water summary update, streamflow conditions across approximately half of the state remain in the below normal condition.
About 82 percent of the subsoil in northwest Iowa is rated as being short of very short of moisture, while soil moisture levels in west central and central Iowa are 77 percent short or very short. Soil moisture levels are generally better across the southern third of the state.
In the Missouri River basin, the U.S. Army Corps of Engineers noted that runoff for July in the upper basin was just 34 percent of normal. Forecasted runoff for 2021 is expected to be 14.6 million acre feet – which is four times less than the runoff in the flood years of 2011 and 2019.
For a thorough review of Iowa’s water resource trends, go to iowadnr.gov/WaterSummaryUpdate.