For starters, don’t dig and install a new storm water detention pond on top of a well-known ground water discharge area, as was done when the City of Madison/Nakoma Road storm water detention pond (aka Secret Pond) was completed in fall of 2011 near the intersection of Manitou Way and Nakoma Road on Madison’s west side (see photo below.
The problem: the practice ultimately degrades drinking water because higher quality ground water (the source of drinking water in the Lake Wingra watershed) becomes contaminated with salt and other pollutants found in storm water. It’s like running drinking water through a dirty sock and then into the tea kettle.
The open water in the photo above and the photo below is from natural spring flow which maintains a year round temperature of about 50 degrees F, and not from storm water runoff entering the pond (notice the two dry box culvert inflow pipes in the center of the photo above). This is not the only pool of spring water on the surface of the storm water pond–look for others the next time you go by.
No community, let alone Madison, can afford to treat its ground water resources with such disregard. In an era when the ground water levels are decreasing, and drinking water is on occasion being pumped from the lakes (that are polluted with road salt and other pollutants) one would hope that City officials would be more careful.
How was this pond permitted to be constructed on top of a spring flow area? It was not for lack of knowledge and awareness. This area on the edge of the UW-Madison Arboretum and the west end of Lake Wingra is well-known for its many springs and groundwater seeps–Duck Pond, Council Springs, Dancing Sands springs, to name a few.
Project proponents including the City of Madison Engineering Department, UW-Madison Facilities Planning & Management and the DNR were well-aware of the natural resources in the area, were warned that this project would have unintended and negative impacts, and rejected a restoration proposal that would have dealt with storm water problems and at the same time avoided the problems created by this new storm water pond.
And yet, the project was approved by the DNR, City Engineering, and UW-Madison Facilities Planning & Management.