Harrison Township

Gloucester County is situated in the Atlantic Coastal Simple Physiographic Province. Beneath Gloucester County lies a series of geological formations that create aquifers, aquifer systems, and confining units (aquitards). These formations primarily consist of unconsolidated sediment layers - clays, silts, sands, and gravels - deposited over millennia and extending hundreds of feet down to bedrock.

The sand and gravel layers form the aquifers, while the silt and clay-rich layers create the confining units. These geological formations in the County gently slope southeast, with the oldest formations exposed along the Delaware River and progressively younger formations appearing as you move southeastward toward the Ocean Coast.

Several major coastal plain aquifers outcrop in Gloucester County. From oldest to newest, these include: the Potomac-Raritan-Magothy (PRM) aquifer system along the Delaware River; the Englishtown aquifer system; the Wenonah-Mount Laurel aquifer; and the Kirkwood-Cohansey aquifer system. The first three aquifers become semi-confined or confined as they extend southeasterly, while the Kirkwood-Cohansey remains exposed throughout the County.

In Harrison Township, groundwater recharge is particularly important. The northwestern part receives recharge into the Wenonah-Mount Laurel aquifer, while the southwestern section recharges the Kirkwood-Cohansey system. Both aquifers are vulnerable to contamination, making protection of the Township's groundwater essential.

The Township's water management plan recognizes that the geological features enable significant water storage and transfer, which helps maintain stream base flow in a more consistent manner than direct runoff would allow. For this reason, groundwater recharge is considered a critical stormwater management strategy in Harrison Township.

Water supply wells in unconfined aquifers have designated "wellhead protection areas" (WHPAs) that outline zones where surface contaminants could potentially reach the wellhead within specific timeframes. These WHPAs include three tiers with travel times of 2 years (Tier 1), 5 years (Tier 2), and 12 years (Tier 3).

Harrison Township has four confined public community water supply wells without associated WHPAs and seven unconfined public non-community water supply wells with WHPAs. These protection zones should be considered in future development planning, zoning decisions, and stormwater management policies.

Surface waters in the Raccoon Creek Watershed are classified as FW-2-NT or FW2-NT/SE2, designating their uses for natural biota maintenance, recreation, agricultural and industrial supply, and potential drinking water after conventional treatment.

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