Posted by Angie Hong | Posted in Water Conservation | Posted on 27-03-2012
Folks living near White Bear Lake have watched their beloved lake slowly shrink in size over the past nine years. Each summer, the water retreats further from the shoreline and docks that were once used for fishing and boating now barely reach the water’s edge, even with lengthy extensions. The phenomenon has sparked vigorous debate, with people blaming the low water levels on everything from raingardens to dry weather. Finally, the White Bear Lake Conservation District enlisted the help of the US Geological Survey who, in partnership with many local and state entities, launched a comprehensive research project to get to the bottom of the problem.
The USGS study analyzed precipitation, lake level and groundwater level data, in addition to using sophisticated field research to characterize groundwater and surface water interactions in the area. In the end, they found that increased groundwater pumping in communities around the lake was just as much to blame for the low lake water levels as the abnormally dry weather in recent years.
In a nutshell, water moves, and not always in a predictable fashion. Surface water flows off the landscape and into lakes and rivers. Groundwater also flows, albeit more slowly, but it can also move vertically or, in the case of White Bear Lake, feed into a surface water resource. The reverse can also be true, as the USGS researchers found that lake water from White Bear is also flowing out into groundwater aquifers and in some places it is actually reaching wells in the Prairie du Chien / Jordan and glacial aquifers.
The problem is that White Bear Lake is located in a rapidly developing region. As the population in nearby communities has increased, so has the number of private and municipal wells drilled and the quantity of groundwater pumped. Groundwater levels have dropped and, as a result, less water is flowing into White Bear and other area lakes.
In a way, the low water levels in White Bear Lake have made a previously invisible problem glaringly evident. The Metropolitan Council has been warning for years that we are using water from underground aquifers in the metro area faster than it is being replaced. In a report released a few years back, the Met Council predicted that aquifers in parts of Washington and Dakota Counties will drop 10 to 20 feet in the next two decades. Meanwhile, the Minnesota Department of Natural Resources reported that between 1991 and 2005, two years with similar rainfall, total groundwater use increased from 200 million gallons to 252 million gallons. This was a 26% increase, even though population during the same time increased by only 18%.
More research is still needed to determine how much water we can safely pump from the Prairie du Chien aquifer without impacting lake levels and without causing lake water to enter nearby wells. Until we know the answer, however, we can take the first step towards reducing municipal groundwater use by modifying our landscaping practices.
Of the household water used during summer months, 80% goes into lawn and garden care, requiring local municipalities to build enormous holding tanks and spend considerable sums of money on pumping and processing. In the City of Woodbury, for example, municipal pumping jumps from 5 million gallons of water per day during the winter to as much as 20 million gallons a day during the summer. Here are four simple steps homeowners and business owners can take to reduce this demand:
1) Water lawns only once a week. Over-watering a lawn can actually result in shorter root systems, making the grass that much more dependent on artificial irrigation to survive. One inch of water a week is sufficient to keep the grass alive and encourage deep root growth. If it rains enough, no additional watering should be needed.
2) Install rain sensors on sprinkler systems. These sensors can be found at local hardware stores for less than $20.
3) Install rain barrels on downspouts to collect and reuse rainwater for gardens. The Washington Conservation District is currently taking orders for their spring rain barrel sale. The 55-gallon barrels are $68 each and can be picked up on April 27 and 28 at the fairgrounds in Lake Elmo (651-275-1136 or www.mnwcd.org to order). Or, attend a free workshop at Hedberg Nursery on Hwy 36 in Grant to learn how to install, maintain and use a rain barrel (April 21, 9-11am – 651-748-3158 to register).
4) Gradually replace lawn with native plants that don’t require watering. Get ideas and find workshop and events at www.BlueThumb.org.
Will people once tell the tale of White Bear Lake and the towns that sucked the whole lake dry? Hopefully not, but the choice is up to us.