PS 49-262 - Monitoring wetland hydrology in Minnesota

Abstract: Hydrological regimes are defining characteristics of wetlands, helping to shape wetland plant communities, wildlife use, and ecosystem services. Multiple pressures, including groundwater use, landscape alterations, and climate change can induce shifts in wetland hydrological regimes. However, the impacts of such shifts are difficult to predict or detect because most wetlands are not continuously monitored, and baseline conditions are unknown. Therefore, the Minnesota Department of Natural Resources is developing a wetland hydrology network to monitor baseline hydrological regimes in reference wetlands. We define reference wetlands as those that have been minimally altered or impacted by human activity and are not expected to experience direct impacts in the foreseeable future. We have installed monitoring wells and conducted baseline vegetation surveys at 25 sites throughout Minnesota. The sites represent multiple wetland types, including deep and shallow marshes, fens, and wet meadows. Water level data collected from 1-4 years of monitoring indicate consistencies in temporal trends among wetlands of the same type and large differences in average water levels based on location. Data collected in 2022 indicate positive and generally strong relationships between water levels and precipitation. In future years, we will expand the network to 60 sites and continue collecting data at existing sites. The long-term records will allow us to characterize normal wetland water levels in the context of variable weather conditions. Consistencies in water level trends among wetlands in the network indicate that these sites can serve as valuable comparisons for restored or potentially impacted wetlands in the future.