08/25/2026
City of Elkhart Response to the July 2026 Flood Event
On July 3 and July 4, 2026, the City of Elkhart experienced an exceptionally rare and severe rainfall event. A slow-moving thunderstorm repeatedly passed over the area, producing approximately 12.60 inches of rainfall within approximately 24 hours in Elkhart, according to the National Weather Service. The rainfall caused flash flooding throughout Elkhart, basement flooding, road closures, and the closure of Interstate 35 between Ankeny and Elkhart. This amount exceeded NOAA Atlas 14 estimates for a 24-hour, 1,000-year rainfall event in central Iowa. A “1,000-year event” does not mean that a storm of this size occurs only once every 1,000 years. Rather, it means the event has an estimated 0.1 percent chance of occurring in any given year. This rainfall event was an extraordinary natural event that could not have been anticipated or prevented by reasonable human foresight or care. The rainfall saturated the ground and significantly increased stormwater runoff throughout the community. Storm sewers, culverts, drainageways, and retention facilities reached capacity, allowing excess water to flow into streets, parks, and yards. Municipal sewer systems are not designed to fully convey storms of this magnitude because doing so would require infrastructure far larger than is practical or economically feasible. Instead, systems are designed to manage more common storms while reducing the impacts of larger events through retention ponds and overland flow routes. Based on the available meteorological and engineering information, the July 3–4 storm was an extraordinary natural weather event that exceeded the level of protection that can be achieved through conventional sewer infrastructure.
Following the significant flooding experienced in 2018, the City Council identified stormwater management and inflow and infiltration (I&I) as two of the community’s highest infrastructure priorities within the City’s capital improvement plan. Although stormwater and sanitary sewer are separate systems, they are closely connected when rainwater or groundwater enters the sanitary sewer through I&I. Inflow occurs when rainwater or surface water enters the sanitary sewer system quickly through direct connections or other openings, while some infiltration may occur when groundwater enters more gradually through unknown subterranean cracks, joints, or other defects that may exist in older portions of the system. Based on the rapid rise in the main lift station’s water level during significant rain events, there appears to be inflow within the system. It is believed a large portion of the suspected inflow is from the west side of town. This is more than likely due to the age and condition of the underground infrastructure. In general, inflow is difficult to track and pinpoint due to wide variety of possible connections into the sanitary sewer system. To address these issues, the City developed a multi-phase stormwater improvement strategy focused on reducing flood risk, improving water quality, addressing known drainage concerns, and preparing for future growth. Completed in 2022, Phase I converted the former wastewater treatment lagoons into stormwater retention ponds. New storm sewer infrastructure now directs runoff from approximately 147 acres into the ponds. The ponds temporarily store stormwater and release it at a controlled rate, reducing peak flows and flooding during routine and moderate storms. During the July 2026 flooding event, the city’s stormwater retention ponds performed as designed by storing a substantial amount of runoff. Additionally, in 2024, the City completed improvements to the Main Lift Station by installing larger-capacity submersible pumps, replacing wet well piping, upgrading electrical and control systems, and increasing the size of the standby generator. These improvements increased system reliability and prepared the community for continued residential growth.
The City continues implementing its long-term sewer improvement strategy in stages as fast as permitted by city finances. In 2026, a new Capital Improvements Plan was approved which includes a sanitary sewer system rehabilitation project in FY2028 to reduce/eliminate infiltration and inflow (I&I). Addressing I&I will provide for additional sewer capacity, prevent emergency repairs, prevent further structural degradation, and prevent basement backups. In 2026, the City selected Bolton & Menk Engineering to complete engineering for Phases II and III of the Stormwater Improvements Project, with construction anticipated to begin in 2027, subject to funding and approvals. Phase II will install storm sewer infrastructure along North Grant Avenue and behind Elm Street, directing additional runoff toward the Prairie Pointe Park retention ponds and reducing flooding west of the newer residential development. Phase III will install additional storm sewer improvements west of Grant Avenue along portions of Elm Street and Maple Street, improving stormwater conveyance and reducing localized flooding during more typical storm events. The project will also provide an opportunity to investigate potential sources of inflow and infiltration within the project areas of Phases II and III.
Although the July 2026 storm exceeded the capacity of conventional sewer infrastructure, the City's completed improvements reduced downstream flooding impacts and functioned as intended. The City remains committed to completing future sewer improvements and strengthening Elkhart's resilience to future storm events.
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