Glaciers, New Jersey and what it means for the Spread of Contamination

Posted on May 14th, 2014

Roughly 30% of the state (most of the northern portion) was carved out by glaciers during the Pleistocene Epoch, with the last period of glacier advance occurring during the Wisconsin Glaciation (starting roughly 80,000 years ago). This glaciation reached its furthest point in New Jersey approximately 18,000 years ago and did not recede until nearly 11,000 years ago. During this time period, glaciers covered much of northern New Jersey, carving New Jersey’s ridges and valleys out of the bedrock and leaving behind a complex system of glacial deposits and moraines. These glacier deposited sediments are characterized by grain sizes ranging from clay to boulders, containing water producing and non-water producing zones, as well as confining and non-confining layers. The composition and thickness of these glacial deposits varies throughout the region and can affect the distribution and spread of contamination.

The different aquifers within northern New Jersey have a diverse set of characteristics that contribute to water and contamination flow. The Buried Valley aquifer system, located in Morris and Essex counties and parts of Union and Somerset, is particularly susceptible to contamination due to the thinness of the soil layers and the shallowness of the water table. The entire aquifer area also acts as the recharge area enabling contamination to spread from one area to another easily. In contrast, both the Fifteen Basin aquifer system (encompassing portions of Hunterdon, Middlesex, Morris, Passaic, Somerset, Sussex, and Warren counties, New Jersey and Orange County, New York), and the Highlands aquifer system (mainly in Passaic County and parts of Sussex, Morris, and Bergen counties, New Jersey and Orange County, New York), have several water producing zones with different hydraulic heads that are traversed by many bedrock wells. These wells aid and enable the spread of contamination from one zone to the next enabling shallower contamination to potentially contaminate the deeper water supply wells. Soils in these aquifers are also thin, contributing to the overall vulnerability of the aquifer to contamination. In the Rockaway River aquifer, located in Morris County, the shallowness of the aquifer influences the amount of contamination that is introduced. Contamination can enter directly from the surface, through contaminated water bodies and localized man-made pollution sources. Another aquifer that can be affected by contaminated surface water is the Ramapo River Basin aquifer system, located across Bergen and Passaic counties, New Jersey and Rockland and Orange counties, New York. Soil in this aquifer is highly permeable and the aquifer is recharged by the Ramapo River. This is also an unconfined aquifer which further decreases resistance to contamination. While the EPA acknowledges that the Ridgewood aquifer system has very high quality water, it is still vulnerable to contamination through the high permeability of the soil and the shallow depth of the groundwater.

What this all means for New Jersey is that contamination can enter into our water system very easily due to topographical features that were carved out thousands of years ago by glaciation. Sources of contamination are everywhere and with so many people provided with water through wells into these aquifers (especially in rural areas), contamination cannot be allowed to spread unchecked through our Garden State.

Jocelyn Bishop

Environmental Scientist

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