IOWA RESERVOIR REPORT

Last Updated: December 21, 2025

The latest observations from Iowa's primary dams and reservoirs indicate that most are maintaining gage heights close to their historical averages for this time of year. Clear Lake, Black Hawk Lake, Lake Panorama, and Spirit Lake are all reporting levels marginally below average, with Clear Lake at 4 feet compared to an average of 4.53 feet, Black Hawk Lake at 7 feet versus an average of 7.15 feet, Lake Panorama at 45 feet against an average of 45.41 feet, and Spirit Lake at 14 feet, just slightly under the average of 14.03 feet. West Okoboji Lake, however, stands out with a gage height of 3 feet, which is more significantly below its average of 4.17 feet. These minor deviations may not yet signal abnormal conditions, but they are notable data points that could suggest trends if they persist or intensify.

Conversely, Corydon Lake's streamflow measurement is substantially above its average, with a current flow of 5 cubic feet per second against an average of 1.96 cubic feet per second. This is an abnormal condition that could be attributed to recent precipitation events or variations in watershed inflows. Meanwhile, Rathbun Lake near Rathbun is slightly below its average gage height, with a current level of 904 feet compared to the average of 906.5 feet. It is important to cross-reference these figures with additional data sources for confirmation, but based on the available data, the most significant anomaly pertains to Corydon Lake, which may warrant further investigation to understand the cause of increased flow, such as checking for possible precipitation events, snowmelt contributions, or changes in land use that may affect runoff patterns. The discrepancies at West Okoboji Lake should be monitored for potential impacts on local ecosystems and water management practices. Overall, while most reservoirs are close to their average levels, specific attention might be needed for Corydon Lake due to atypical streamflow and West Okoboji Lake for its lower-than-average gage height at this time of the year.

Iowa has several major reservoirs, including Coralville Lake, Rathbun Lake, and Saylorville Lake. These reservoirs are primarily fed by the Iowa River, Des Moines River, and Chariton River, respectively. Snowpack and mountains are not significant factors in Iowa's hydrology. Coralville Lake has experienced record high water levels in the past, with flooding in 2008 and 2013 causing significant damage. Drought conditions have also affected Iowa's reservoirs, with Saylorville Lake reaching record low levels in 2012. Seasonal trends in Iowa typically involve greater precipitation in the spring and summer months, leading to higher reservoir levels. However, prolonged periods of drought can disrupt this pattern. Overall, reservoirs and dams serve an important role in managing Iowa's water resources and mitigating the risk of floods and droughts.

Iowa has several major reservoirs, including Coralville Lake, Rathbun Lake, and Saylorville Lake. These reservoirs are primarily fed by the Iowa River, Des Moines River, and Chariton River, respectively. Snowpack and mountains are not significant factors in Iowa's hydrology. Coralville Lake has experienced record high water levels in the past, with flooding in 2008 and 2013 causing significant damage. Drought conditions have also affected Iowa's reservoirs, with Saylorville Lake reaching record low levels in 2012. Seasonal trends in Iowa typically involve greater precipitation in the spring and summer months, leading to higher reservoir levels. However, prolonged periods of drought can disrupt this pattern. Overall, reservoirs and dams serve an important role in managing Iowa's water resources and mitigating the risk of floods and droughts.