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Home site assessments protect water quality

Mapping out your home site can help identify activities that pose risk to water resources.

The water cycle connects water above and below the ground. What you do in and around your home can affect the water quality both below ground and in nearby lakes, rivers, streams and other surface water bodies. It is important to consider the physical characteristics of your home site as well as potential sources of contamination. These characteristics may speed up or delay a contaminant’s effect on water resources. You may find that you need to take steps to correct practices which might impact water quality.

There are several physical characteristics of your home site to consider:

  • Soil type and depth
    It is important to know what soil type(s) are present on your property, specifically what percentage of sand, gravel, and/or clay is present and in what amounts. Depending on the soil type, you may either be at increased risk for contamination either to groundwater or surface water. Soil particle size influences which pollutants are able to reach groundwater.  Clay particles are tiny and slow the downward movement of water, whereas sand allows more rapid water movement. In other words, different types of soil have properties that permit water and contaminants to seep through or run off at varying rates. With regard to soil depth, typically the greater the soil depth, the farther water must soak down before reaching groundwater. The greater the distance, the more filtration of contaminants is likely to occur.
  • Depth to and type of bedrock
    Depending on where you are in Michigan, bedrock can be at the surface or hundreds of feet below the ground. Certain rocks have different levels of permeability, with some more effective at preventing the downward movement of water and contaminants.
  • Depth to water table
    The water table is the boundary between saturated (where water fills all pore spaces) and unsaturated soil (where the pore space between soil and rock contains air, plant roots, soil organisms and/or some water). Groundwater is water stored in saturated soil below the water table. In general, the closer the water table is to the land’s surface, the greater the risk to groundwater contamination.
  • Location of nearby surface water bodies
    If there is a lot of clay in the soil, which is not very permeable, especially at the ground’s surface, the clay might cause spilled pesticides, chemicals or other contaminants to run off across the land into a nearby water body, rather than to soak into the ground. This type of soil might encourage surface water runoff directly into storm drains and other surface water bodies. In addition, the slope of your property can also increase the risk of surface erosion and runoff.
  • Watershed
    Everyone lives in a watershed, the area of land that drains to a common body of water. What happens on your property can affect the entire watershed and beyond, and thus it is important to understand how the water in and around you is connected to water bodies further away. The next time you use fertilizers or pesticides, consider how the use of these products may impact the lake you live on or the water you drink.

Once physical characteristics are mapped out, create an aerial view of your property.  Mapping this out will help you identify potential issues, and allow you to make changes to minimize risks. Things to include are location of septic system, drinking water well, outbuildings, compost piles, water features, landscape and other built features with hard surfaces (such as rooftops, paved patios, roads, walkways) where runoff may be an issue, location of chemical storage areas and other potential pollution sources, location of storm drains, and areas where drainage is an issue, and general water flow patterns.

The “Home*A*Syst Guide – Home Assessment Guide” (WQ51) helps assess your potential for environmental risks in and around your home. Chapter one of this guide describes step-by-step how to create a site assessment. Printed copies are available at no cost through the MSU Extension Bookstore or electronically from the MSUE Oakland County web site.

Another guide that outlines steps to create a base map of your property is “Landscaping for Water Quality: Garden Designs for Homeowners.”

Now that you have thoroughly considering the physical characteristics of the site and have created a base map, Michigan State University Extension hopes it will be easier to identify potential problems on your property and take the necessary steps to reduce environmental impacts.

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