Frequently Asked Questions

There are many reasons why shoreland zoning and developing 75 ft from a lake or stream are of value. Review the reasons shoreland zoning is in place: The Value of Shoreland Zoning (PDF).

• Runoff from asphalt contains petroleum products that are toxic. Polycyclic aromatic hydrocarbons (PAHs, from petroleum) are widespread contaminants in urban aquatic sediments … Sources of petrogenic PAHs include fossil fuels such as unprocessed coal and crude and refined petroleum products (gasoline, diesel, motor oil, home heating oil, lubricants, and asphalt). Some PAHs are toxic, carcinogenic, mutagenic, and (or) teratogenic and can therefore be detrimental to aquatic organisms. This information came from a study by U.S. Geological Survey researchers in WI.
• Runoff from asphalt seal coated with coal-tar-based products are more toxic. Sealcoating driveways is recommended by the applicators every 1 to 5 years. Most sealcoat products are either coal-tar or asphalt emulsion, although some alternative products now are available. Coal tar and coal-tar pitch have extremely high concentrations of PAHs as do coal-tar-based sealcoat products, which typically are 20 to 35% coal tar or coal-tar pitch. Asphalt and asphalt-based sealcoat products have much lower concentrations of PAHs.
• Runoff from coal-tar-seal coated pavement, even runoff collected more than 3 months after sealcoat application, is acutely toxic to fathead minnows and water fleas, two species commonly used to assess toxicity to aquatic life. See this U.S. Geological Survey factsheet (PDF), which outlines impacts of sealcoat products on aquatic life and people.