Source Water Protection Activity Guide

Quick Select

Use any of the following drop-down menus to navigate through the guide. Choosing a potential contaminant source category from the drop-down menu will narrow your potential contaminant source choices. Choosing a protection activity category from the drop-down menu will narrow your protection activity choices.

Contaminant Type

Potential Contaminant Source Category Potential Contaminant Source

Protection Activity Category Protection Activity

Low Impact Development: Impervious Surface Reduction

Protection Activity: Best Management Practices

Low impact development is an approach to land development (or redevelopment) that incorporates natural features to manage stormwater and protect water quality. Low impact development minimizes runoff by promoting infiltration, evapotranspiration, and collection for use through natural landscape features and fewer impervious surfaces. The result is a functional and visually appealing development that treats stormwater as a resource, not as waste. 

Impervious surfaces are those such as roads, buildings, housing developments, and parking lots that replace natural landscapes as development occurs. Impervious surfaces can affect water quality, streamflow, and flooding characteristics of streams, particularly in urban and suburban areas where storm drains carry significant runoff from roofs and paved areas to nearby waterways rather than allowing rain and snowmelt to soak into the ground. Stormwater runoff can carry pollutants such as oil, dirt, chemicals, and lawn fertilizers directly to streams and rivers where they harm water quality. In contrast, rainfall in vegetated watersheds is absorbed into soils (infiltration), stored as ground water, and slowly discharged to streams through seeps and springs. Flooding is less significant in these watersheds because some of the runoff during a storm is absorbed into the ground, lessening the amount of stormwater runoff into a stream.

 As development and impervious surface area increase, flooding can occur more frequently, impacting water quality. Reducing impervious surface area can reduce runoff and impacts to water quality. Options include using landscaped center islands, porous pavement materials, or mulch and gravel, which helps reduce site runoff rates by maximizing surface roughness, infiltration opportunities, and flow paths. Structural controls can also be used, such as building common driveways on adjoining lots so one driveway can serve both properties. 

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