Groundwater Shortage

IS THERE ENOUGH GROUNDWATER?

By: Michael Sklash, Ph.D, P.Eng.

and

Sharon Mason-Merrill, M.Sc., CPG, CGWP

November 28, 2001

Is there enough groundwater? Based on the recent news, you might think not.

You may think there is a groundwater shortage after considering the Michigan Department of Environmental Quality’s (MDEQ's) recent (November 15, 2001) press release signaling their intention to increase their scrutiny of large-scale groundwater withdrawals. The catalyst for the MDEQ’s increased vigilance is, at least in part, the controversy surrounding the huge groundwater withdrawals now approved for the Perrier owned, water bottling plant in Mecosta County. Similarly, the recent report in The Detroit Free Press (November 24, 2001) on the “feud” over groundwater between Lenox Township residents and the City of Richmond in Macomb County also suggests a groundwater shortage. What exactly is the problem?

In “Groundwater 101,” you learn that when you pump groundwater from a well, the groundwater levels in and around the well decline. This “drawdown” in the water levels is the driving force that brings groundwater to the well from the surrounding ground. The size of the “drawdown cone,” which results from pumping, depends on three main factors: the nature of the geologic formation (called an “aquifer”) that provides the groundwater, the pumping rate from the well, and how long the pumping continues. Drawdown cones commonly range in depth from a few to hundreds of feet at the pumping well and extend from tens to 1,000s of feet away from the pumping well.

Another important concept that you learn in Groundwater 101 is that drawdown is additive. This means that if the drawdown due to my well is 10 feet and the drawdown on my property, due to the big golf course well located down the road, is five feet, then the total drawdown on my property will be 15 feet. Since drawdown is additive, the likelihood of experiencing excessive drawdown in an aquifer increases with the number of neighboring users of the aquifer.

There is a wide range of potential problems associated with excessive drawdown. The Lenox Township-City of Richmond “feud,” mentioned earlier, focuses on the question of whether residential wells are drying up due to excessive drawdown caused by municipal wells. In Mecosta County, Perrier investigated the potential for local streams, wetlands, and lakes to dry up in response to their massive commercial groundwater pumping. As we have seen in municipal water supply aquifers in Kalamazoo and countless other cities, drawdown cones can capture man-made contamination and impact an entire groundwater supply. Although we have not encountered local examples of significant subsidence due to groundwater withdrawal, flooding during storms, reversal of sewer flow, and damaged buildings in places such as Houston, Texas and Venice, Italy are good examples of infrastructure problems arising from subsidence due to excessive drawdown.

There is no good excuse for excessive drawdown. Excessive drawdown is analogous to the: “I ran out of time” versus the “I didn’t manage my time” argument. The science needed to plan and manage groundwater was published decades ago. The tools that we have for planning and managing groundwater are better than ever before. We simply need to use the science, plan, and manage.

This means that we need to adopt a big picture, planned approach when considering groundwater withdrawals. Instead of asking, “Will this well provide enough water for my plant, golf course, house, or municipality?” We need to determine whether the aquifer can provide enough groundwater for all of the stakeholders and ecosystem needs, now and in the future. This requires a thorough investigation of the aquifer on a regional basis including its dimensions, its hydraulic properties, its recharge and discharge areas, and its groundwater - surface water interactions. We need to ask who is currently using groundwater, where, and how much? We need to evaluate how a proposed withdrawal will impact the aquifer. We need to ask these questions now and we need to update the answers on a regular basis…and then there will be enough groundwater!

There is a bright side to the existing and potential problems associated with excessive drawdown in Michigan. First, groundwater is a renewable resource. Second, although few consultants use it, there is a significant body of groundwater information available from county health departments, watershed councils, the State, and the US Geological Survey that can help in planning or re-planning groundwater use. Third, there are well-established engineering approaches for managing and augmenting groundwater resources.

Now is the right time to step back, take a good look at our groundwater resources, examine our development plans, and formulate living groundwater management plans that will ensure we have enough groundwater into the foreseeable future.

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