Why does our watershed drain the way it does?
Wetlands in VLAWMO were formed 9,000-12,000 years ago by glacial activity. As the glaciers receded, depressions and sediment were left on the land. Many of the carved depressions were filled with water where the land relatively flat, or if the land surface was close to the water table. These areas are what give us our current wetlands.
A wetland is an area where water either covers the soil or is present near the surface of the soil. A wetland can hold water constantly or even just part of the year to influence area plants, soil, and hydrology.
While wetlands have been avoided and looked down upon for many years, they're also a part of the Vadnais Lake area history. In early settlement years, wetlands provided resources that supported survival. Tamarack trees for example, grew along wetlands and were what the Vadnais and Garceau families used build their homes. Wetlands were the original flood control infrastructure, the natural purifier for drinking water, and provided spaces for hunting and for fish to spawn.
More than 50% of Minnesota contains shallow groundwater, a condition where a high groundwater table (saturated soil) is near the land’s surface, often indicated by a wetland. Unlike deep ground water, shallow groundwater moves according to gravity along the earth’s surface. Soil exposed to shallow groundwater becomes anaerobic, or what’s called hydric. While the state of the water table changes year to year depending on rainfall and surface runoff, hydric soils remain for many years after shallow groundwater has shifted (part B in diagram below). This is why may properties in VLAWMO experience difficulties with soggy yards and flooding. During a wet year with high rainfall, hydric soils quickly function as they once did – as a wetland. The challenge however, is that wetlands and groundwater are closely connected. To protect the future of groundwater resources, wetlands are key.
Diagram courtesy of USGS
But don’t fret! It’s possible to be at peace with our groundwater, enjoy your yard, and still be of help to our shared water resources. With some planning, patience, and flexibility, VLAWMO is here to help create solutions.
Either of these solutions, or a combination of the two, may be what works best for you. We understand that yards are special places for relaxation and play. Working with your topography, drainage, and personal preferences, VLAWMO can provide technical advice and cost-share funding to help along the way.
History of Drainage Policy:
The issues we face today are a reflection of our history with water. Understanding where we’ve been helps us face today’s challenges. See the BWSR history and DNR history web pages for more on this topic.