TRUE BLUE Lawns

Install Pervious Driveways, Paths and Patios

What is the difference between pervious and impervious surfaces?

Pervious Surfaces

Examples of pervious surfaces: gravel driveways, wood decking, concrete lattice pavers, brick and porous asphalt
Allow water to percolate slowly into the ground
Reduce the amount of polluted stormwater flowing into our streams and Torch Lake
Slow the rate of polluted stormwater flowing off your land
Help to recharge groundwater

Impervious Surfaces

Examples of impervious surfaces: asphalt driveways, stone slabs and steps, concrete garage aprons and sidewalks & patios, buildings (homes, garages, sheds, pole barns)
Do not allow water to percolate into the ground
Accelerate stormwater runoff
Concentrate runoff and create erosion problems or make them worse

Photo: Trish Narwold

How do impervious surfaces impact Torch Lake?

When just 12% of a watershed is covered with impervious surfaces,

the amount of stormwater run-off flowing off the land and into the lake increases.
the water quality begins to decrease.

Stormwater run-off carries pollutants (nutrients, toxins and sediment).

More stormwater run-off means more pollutants
More stormwater increases erosion
More stormwater negatively impacts aquatic creatures and fish

What are the benefits to you and our water?

Keeps toxins out of Torch Lake so they won’t harm fish and aquatic creatures
Keeps sediment out of Torch Lake so it won’t harm fish and aquatic creatures
Keeps nutrients out of Torch Lake, so algae won’t grow and change its turquoise color to green

What can you do?

Step 1. Limit impervious surfaces on your property by making your paths, patios and driveways out of pervious or absorbent materials.

Check the ratio of impervious to pervious surfaces on your property.

Estimate the number of square feet of each type of surface,

The best balance should be 10:90, impervious: pervious.

Photo: Trish Narwold

Image: NOAA

Step 2. Choose these pervious materials.

Pathways—Pervious Options

Pea Gravel
Stepping stone—Flagstone
Permeable pavers
Pervious concrete
Mulch

Driveways-Pervious Options

Gravel and dirt (the old 2 track)
Pervious concrete
Porous asphalt
Permeable pavers

Step 3. Plant more trees

Setting	% Impervious surfaces	% Stormwater Run-off
Forest floor	0	10%
Low Density Residential Area (1 unit/2.5 acres) Similar to Torch Lake Watershed	12%	20%

Links

Consider how much you value the high-water quality of Torch Lake.

Pervious surfaces may cost 4-15% more than impervious surfaces—but Torch Lake is worth it!

Considering coal tar sealant on your driveway? Learn how it will increase toxins in your house and Torch Lake.

If you do have an impervious asphalt driveway already:

Do NOT coat with coal tar sealant. Instead coat with an asphalt- based sealant.
Coal tar is toxic to you, your family and aquatic life.
It releases PAH (polycyclic aromatic hydrocarbons) dust that gets tracked into your house and carried with stormwater to streams and Torch Lake
Plant a Rain Garden around the driveway or in a depression running from the driveway to catch and filter stormwater run-off.

Find more Caring for Water ideas in TRUE BLUE Landscaping

Don't just wish that Torch Lake will stay blue.
Choose a water-friendly lifestyle - make a difference!