Linking Land Use to Water Quality

The Problems

Studies have shown that there is a significant relationship between water clarity in a lake and the value of the land on that lake.

In Itasca County, MN, the estimated market value of the land (not including buildings) averaged $700 per foot of shoreline on the clearest lakes, while the murkiest lakes had much lower property values.

Lakes and the Economy ¹

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Land Use and Phosphorus Runoff ²

One pound of phosphorus equals up to 500 pounds of algae and other aquatic plants.

In general, declines in water clarity are caused by a process called eutrophication (excessive plant and algae growth due to increased nutrients in the lake). In Minnesota, most lakes undergo eutrophication because of increased phosphorus runoff. Different types of land use contribute different amounts of phosphorus in the runoff into lakes. Many other types of pollution can also come from developed areas, including other nutrients such as nitroten, excess sediment, pathogens, toxic contaminants, debris, and thermal stress. Poorly planned development can lead to increases of these pollutants in lakes, resulting in a decrease in water quality.

In addition, intense development may bring other unintended consequences, such as loss of habitat for fish, waterfowl, and other creatures, increased noise levels, contaminated drinking water, lakeshore erosion, and more.

The Solutions

Planning, Zoning, and Enforcement

Zoning is one of the most important tools available to a community to prevent lake degradation. The state of Minnesota sets minimum standards for shoreland zoning, including the following activities, among others:

These minimum standards should not be applied in a “one-size-fits-all” fashion because they cannot prevent degradation in all lakes. Therefore, the state encourages local governments to adopt zoning standards that are more restrictive, especially for their highest quality resources.

Site Design & Low Impact Development

The good news is that development can be done in a way that’s friendly to the environment. Your community’s policies should encourage development that:

• retains and restores the natural landscape
• promotes infiltration and reduces runoff
• maintains or restores natural buffer areas around lakes and streams

Development on land creates impervious surfaces; these surfaces do not allow water to filter into the ground dramatically increasing the amount of runoff, and degrading water quality:

Best Management Practices (BMPs) and Maintenance

While the best BMP is Better and More Planning, other BMPs such as rain gardens, erosion control, street sweeping, and public education can be effective at reducing pollution if properly executed and maintained. In addition, maintaining septic systems, especially in shoreland areas, is key to preventing system failure, which releases nutrients and pathogens into our waters.

Sources:

1. Mississippi Headwaters Board (2003), University of Maine (1996), Itasca County Assessor’s Office (2003)
2. Center for Watershed Protection