IOWA RESERVOIR REPORT

Last Updated: February 1, 2026

Iowa's dams and reservoirs are integral to water management, recreation, and ecosystem health. Based on the latest observations, most reservoirs appear to be operating within normal levels, with gage height measurements close to their averages. Clear Lake's current level is slightly below the average at 4 feet compared to 4.53 feet, indicating a potential decrease in local inflow or an increase in water usage. Black Hawk Lake, Lake Panorama, and Spirit Lake also exhibit minor deviations from their average storage levels, which could be due to seasonal variations or recent weather patterns. The larger Rathbun Lake is similarly just below its average level, potentially impacting water supply if trends continue. However, West Okoboji Lake and Corydon Lake are displaying more significant variances from their averages, which may raise concerns for management authorities.

Specifically, West Okoboji Lake has seen a drop in gage height to 3 feet from an average of 4.17 feet, suggesting lower-than-expected water input or higher outflows. This anomaly could be associated with recent mild weather patterns, as reported by KCCI, which may have led to reduced snowpack and consequently lower river flows into the lake. Conversely, Corydon Lake's streamflow is considerably above average, measuring at 5 cubic feet per second against an average of 1.96 cubic feet per second. This spike could be influenced by factors such as localized precipitation or agricultural runoff, especially considering the concerns about manure pollution highlighted by thegazette.com. It is crucial for the Iowa Department of Natural Resources and other relevant bodies to monitor these variations closely, as they may have implications for water quality, supply management, and ecosystem balance. Cross-referencing these observations with local news sources and weather reports adds context, indicating that recent weather patterns and environmental issues might be influencing water levels and streamflow in these water bodies.

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.