DETERMINING DISCHARGE FROM THE FALLASBURG DAM AND THE HYDROLOGY OF THE FLAT RIVER BYPASS CHANNEL, LOWELL, MICHIGAN

River channel discharge is determined by surface flow and groundwater interaction. Flow meter readings taken repeatedly over months at a transect 0.5 mile downstream from the Fallasburg Dam show that the Flat River Bypass Channel in Lowell, Michigan, is receiving less than the required dam release of 110 cfs. Monitoring wells, river stage levels, a flow meter, a seepage meter, stable isotope analysis and chemistry analysis were used to determine whether the river was gaining or losing between the dam and the transect location. Four monitoring wells installed along the river provided groundwater levels and the groundwater gradient. Seepage meter readings in the streambed point to a losing river. Flow meter readings taken at the dam and 0.5 mile downstream on the same afternoon reveal losing conditions. River stage data combined with discharge data indicate that the river shifts seasonally from gaining to losing conditions. Water chemistry and stable isotope analysis are being processed for information on the interaction between groundwater and stream discharge. The river valley topography and local climate suggest the region should experience gaining conditions, but results show a more complicated hydrological system with varying gaining and losing sections which correlate to seasonal shifts in precipitation. Further analysis is underway to better understand the interactions between surface water and groundwater along the Flat River Bypass Channel.