A recent U.S. Geologic Survey study showed that the largest contributor to the rise of a toxic pollutant in urban lakes and reservoirs across America is a black sealant sprayed on driveways and parking lots.

The Seattle Times reports that the research was based on a sampling of sediments from the bottom of 40 lakes and reservoirs in commercial and residential areas in cities and suburbs typical of where most Americans live — not near old industrial sites.

One of the lakes in the Seattle area with high levels of the polycyclic aromatic hydrocarbons (PAH) is Mountlake Terrace’s own Lake Ballinger.

Lake Ballinger had 16.61 milligrams per kilogram total PAH, with 11.83 from sealant.

Though this is considered high, according to the USGS, the Probable Effect Concentration, or the concentration that is expected to harm bottom-dwelling plants and animals, is 22.8 milligrams per kilogram of sediment, or parts per million.

Read more at the Seattle Times and also check out the video report from King 5 below.

P.S. Try to ignore the fact that King 5 spelled our city’s name “Mount Lake Terrace” and that the footage at the beginning of the report isn’t actually in Mountlake Terrace, but Edmonds.