Threat: Impervious Cover

Impervious Cover

Impervious surfaces are paved parking lots, roadways, and roofs. During rain storms and snow melt, water running off of impervious surfaces carries pollutants and sediments into streams, lakes, and estuaries. To keep waters clean, impervious surfaces should be a low percentage of the total amount of land areas of the watershed basin. NHDES recommends no more than 10% impervious cover for a town.

Within the last 20 years impervious surface covering the Piscataqua Region Watershed has increased from 28,695 acres in 1990 to 63,241 acres in 2010. Overall, the population for the 52 municipalities in the watershed has grown by 19% from 316,404 in 1990 to 377,427 in 2010. During this same period, the total impervious surfaces within the towns grew by 120%. Therefore, the rate of increasing impervious surfaces has been six times the rate of population growth.

[HC.JS:CochecoICcsv,column,Cocheco River Watershed,Percent Impervious Cover,400,NH DES Recommendation:10]
Cocheco River Impervious Cover

Cocheco River Impervious Cover – click to view larger Balance is key. PREP recommends no more than 10% impervious cover and no less than 20% conserved land in a watershed.

 

[HC.JS:ExeterSquamscottICcsv,column,Exeter-Squamscott River Watershed,Percent Impervious Cover,400,NH DES Recommendation:10]
Exeter-Squamscott River Impervious Cover

Exeter-Squamscott River Impervious Cover – Click to view larger PREP recommends no more than 10% impervious cover and no less than 20% conserved land in a watershed.

[HC.JS:HamptonSeabrookICcsv,column,Hampton-Seabrook Watershed,Percent Impervious Cover,400,NH DES Recommendation:10]
Impervious Cover Hampton-Seabrook

Impervious Cover Hampton-Seabrook – Click to view larger PREP recommends no more than 10% impervious cover and no less than 20% conserved land in a watershed.

[HC.JS:LampreyICcsv,column,Lamprey River Watershed,Percent Impervious Cover,400,NH DES Recommendation:10]
Impervious Cover Lamprey River - Click to view larger

Impervious Cover Lamprey River – Click to view larger PREP recommends no more than 10% impervious cover and no less than 20% conserved land in a watershed.

 

[HC.JS:OysterBellamyICcsv,column,Oyster-Bellamy River Watershed,Percent Impervious Cover,400,NH DES Recommendation:10]
Impervious Cover Oyster-Bellamy River - click to view larger

Impervious Cover Oyster-Bellamy River – click to view larger PREP recommends no more than 10% impervious cover and no less than 20% conserved land in a watershed.

 

[HC.JS:SalmonFallsICcsv,column,Salmon Falls River Watershed,Percent Impervious Cover,400,NH DES Recommendation:10]
Impervious Cover Salmon Falls River - Click to view larger

Impervious Cover Salmon Falls River – Click to view larger PREP recommends no more than 10% impervious cover and no less than 20% conserved land in a watershed.

 

[HC.JS:WinnicutCoastalICcsv,column,Winnicut-Coastal Watershed,Percent Impervious Cover,400,NH DES Recommendation:10]
Impervious Cover Winnicut-Coastal - Click to view larger

Impervious Cover Winnicut-Coastal – Click to view larger PREP recommends no more than 10% impervious cover and no less than 20% conserved land in a watershed.

PREP is part of the U.S. Environmental Protection Agency’s National Estuary Program, a joint program between local, state and federal agencies established under the Clean Water Act with the goal of protecting and enhancing nationally significant estuarine resources. PREP is supported in part by an EPA matching grant and is housed within the School of Marine Science and Ocean Engineering at the University of New Hampshire.

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