The St. Joseph River Basin Commission hired Christopher B. Burke Engineering to develop a flood risk management plan to assess the overall functional health of the North Branch of the Elkhart River (NBER) and identify opportunities to mitigate flood hazards. This project was supported by a Grand Challenge grant from the Environmental Resilience Institute at Indiana University. Project partners included the Conservation Law Center and Robert C. Barr, a Hydrologist and Fluvial Geomorphologist from IUPUI.
After performing field inspections and analyzing historic precipitation and streamflow data, the NBER was found to be an incredibly resilient and healthy river system due to the large storage capacity of numerous lakes and relatively little wetland loss. These attributes, combined with the groundwater driven nature of the system, make the NBER a unique tributary of the St. Joseph River. The fact that increased annual rainfall and storm intensity have not significantly increased flow volumes downstream demonstrates the stability of this watershed.
Although the mainstem of the NBER is stable, instability was found in the headwaters of the Middle Branch above Sylvan Lake. This was mainly due to channel modifications and floodplain disconnection downstream of the City of Kendallville. The negative impacts of these changes are generally not experienced beyond Sylvan Lake because the lake traps sediment and serves as a hydrologic shock absorber, which reduces negative impacts further downstream in the NBER.
The study concluded that nature and location of flooding in the NBER watershed is the product of geology and climate, two factors that cannot be controlled. According to the plan, attempts to control natural fluctuations should be avoided in favor of adaption strategies. Based on the findings of this study, it is not likely feasible or cost-effective to significantly reduce flood problems for homes that were built in the floodplain by creating additional upstream storage, clearing vegetation downstream, or by more intensive means of increasing the outflow from lakes without creating negative impacts elsewhere. What is recommended instead is to take a series of steps to adapt to higher lake levels and flooding patterns. These steps include protecting homes and reducing vulnerability to flood damages through the adoption of specific strategies for maintaining the inherent resiliency of the NBER watershed. To access this plan, click here.