Students Investigate Groundwater Sustainability in the Lower Peninsula of Michigan
Background. The State of Michigan – although surrounded by the Great Lakes – relies heavily on groundwater to support its different water-use sectors. Over 700 million gallons are withdrawn each day to support agricultural and industrial activities and provide drinking water supplies to roughly half of all Michigan citizens. There are, however, limitations to potable groundwater supplies in regions of the State, particularly in the low-lying and coastal regions of the Lower Peninsula (LP). In these areas, shallow saline groundwater occurs, in many cases making the groundwater unfit for human consumption and for agricultural uses and detrimental to the environment. Based on analysis of groundwater chemistry from sites in east-central LP of Michigan and a few other scatted locations, researchers have suggested that the salinization is due to upward movement of brines – or hypersaline pools of groundwater in the deep geologic formations.
In recent years, Ottawa County – which resides in the low-lying coastal area of west-central LP of Michigan – has reported elevated groundwater salinity in water wells. Ottawa also happens to be the fastest growing county in Michigan, and unchecked increases in groundwater withdrawals have been used to support rapid population growth and expanded agricultural activities. These observations prompted officials at the township, county and state levels to ask:
- Are the scattered occurrences of saline groundwater across southern Michigan related? (Is brine upwelling systematically impacting low-lying areas in across the LP of Michigan?)
- How has pumping impacted the amount groundwater availability in our shallow aquifers? (Have increases in groundwater pumping triggered groundwater salinity problems, e.g., in Ottawa County?)
- What is the long-term sustainability of our groundwater resources? (How can we best manage our groundwater resources while promoting growth and development?)
Collaborative Study: A large-scale, 4-year study was completed through cooperative efforts between different stakeholders, researchers, planners, and outreach specialists Michigan State University (MSU) and Ottawa County, with a goal to understand and characterize the integrated groundwater quantity and quality dynamics associated with the brine upwelling process. The specific parties involved were:
- MSU Dept. of Civil and Environmental Engineering (CEE). Led by Professor Shu-guang Li and Zachary Curtis, ESPP student and environmental engineering Ph.D. candidate – this team was responsible for compiling datasets for statewide analysis and developing groundwater flow simulations to better understand the Ottawa County aquifer system. They also led the execution of a large-scale field sampling campaign in Ottawa County, which included MSU postdocs, graduate students, and more than 50 undergraduate students.
- Ottawa County Planning and Performance Improvement Department (PPID). The Ottawa PPID team organized and facilitated routine meetings between the MSU groundwater research team and the Groundwater Task Force – an external committee of technical experts, stakeholders (e.g., well drillers) and managers/decision-makers at the township, county, and state levels. They also provided key data/ information needed to analyze water groundwater dynamics in Ottawa County.
- MSU Institute of Water Research (IWR). Specialists from MSU IWR developed a web-based decision support system (DSS) designed to assist with site-scale analyses and decision-making within the county. They also created a Management Guidebook for the county and a Statewide Action Plan based on the modeling and analysis completed by the groundwater research team (see Shaping Policy below).
The research assimilated a variety of groundwater data sources, including high-density, statewide water wells datasets that are often that was often deemed by many as too noisy and too crude to be useful. Part of Zach’s dissertation work focused on a novel approach that allowed uncovering hidden complex patterns in groundwater flows – from statewide scale to regional scale to local scale – using these statewide databases. This work helped to confirm that brines are systematically impacting low-lying areas where groundwater is discharging.
The study also developed and applied a data-intensive modeling approach that allows simulating the complex interplay of the natural upwelling processes, human activities (associated with agriculture and food production), and climate change. By combining field sampling, data mining, geologic/geostatistical modeling, and process-based hydrological modeling, the research team demonstrated that local-scale impacts of brine upwelling in Ottawa County are controlled by: i) streams and rivers – which act as ‘natural pumps’ that bring deeper groundwater to the surface; ii) the occurrence of nearly impervious geologic material at the surface – which restricts freshwater flushing of deeper groundwater; and iii) the space-time evolution of water well withdrawals – which, over time, induces migration of saline groundwater from its natural course. Screening-level evaluation of water quality, subsurface geology, and groundwater flow patterns in 33 other counties identified as ‘at risk’ revealed that many of the issues facing Ottawa County are being experienced in the other low-lying counties across LP of Michigan.
Guiding Future Management. These findings triggered an urgent response from local government officials to reduce/reverse the negative impacts on the groundwater system in coming years of growth and development. Using carefully planned projections of groundwater use and land use/land cover change developed by planners from the Ottawa County Planning and Performance Improvement Department (PPID) and Ottawa County Public Utilities Department, the calibrated groundwater model was applied to explore groundwater conditions for the next 20 years (2015-2035). This ‘future modeling’ effort identified areas prone to groundwater shortages and/or problematic levels of groundwater salinity and will help guide the development of a long-term groundwater monitoring network needed to refine/verify the modeling results and steer adaptable management of the county’s groundwater resources.
Shaping Policy. A key aspect of this large-scale collaborative project was to disseminate the key findings and practical management implications to relevant persons so that sound policy decisions can be made moving forward. In December 2017, Zach and MSU CEE presented to stakeholders and decision-makers from Ottawa County and the Michigan Department of Agriculture and Rural Development. Zach will also present findings at the Annual Conference of the International Association for Great Lakes Research on June 19, 2018. Two detailed technical reports on the statewide and Ottawa County modeling efforts were developed by MSU CEE, and MSU IWR recently developed both a statewide action plan (with a suggested prioritization of future study areas) and groundwater management guidebook for Ottawa County based on the modeling results. The distribution of this wealth of meaningful information will help inform decision-makers, planners and resource managers charged with protecting and sustaining groundwater resources in Michigan and beyond.
- Zachary Curtis via ESPPulse Spring 2018