NATURAL and CULTURAL FEATURES of MONMOUTH COUNTY

of the tested wells exceeded one or more of the recommended upper limits and/or optimum range
for secondary (aesthetic) parameters, e.g., iron. Monmouth had the highest amounts of iron in
well water of all the counties; an ion exchange conditioner that removes iron from the drinking
water for a family of three or four with moderately hard water can contribute up to 1452 lbs per
year of dissolved sodium chloride (halite salt) to surface and groundwater (Panno et al., 2002).
Of the 343 wells statewide that exceeded the MCL for Volatile Organic Compounds (VOC) –
which indicate pollution from solvents, paints, gasoline, oil etc. – the most common VOCs were:
trichloroethylene (136), tetrachloroethylene (108) and benzene (33) (NJDEP, 2006). The first
two are often associated with dry cleaners, the last with gasoline from leaking Underground
Storage Tanks (USTs).
IRON AND SULFUR
Since the first iron works in New Jersey was constructed around 1674 in Tinton Falls,
Monmouth County was mined for limonite (iron oxide: locally known as bog iron, ironstone,
peanut stone, or hardpan), an orange colored precipitate produced in acidic streams and marshes
that contains up to 40% iron; a few geologic formations, such as the Manasquan, also have
deposits of siderite (iron carbonate) (Keelen, 2003; Forman, 1998). This industry peaked after
the war of 1812 until about 1844, when transporting coal as well as richer ores of iron from
Pennsylvania and other states west of NJ became more cost effective (Forman, 1998).
As acidic groundwater seeps into a stream and becomes oxygenated surface water, dissolved
ferrous iron (Fe(ii)) will precipitate out of solution to ferric iron oxide (Fe(iii)), raising the pH
somewhat as it changes to iron hydroxide (variants of Fe(OH)) (Dahlgren, 1977). The
Leptothrix, Clonothrix and Gallionella bacteria derive their metabolic energy by oxidizing iron;
the acidophilic autotroph, Ferrobacillus ferroxidans, is able to oxidize iron in low pH
environments (Biovir, 2005). There is such a predominance of slimy iron bacteria floc in County
streams that many look like they have been impacted by ‘Acid Mine Drainage’. Iron bacteria
also produce a biofilm with an iridescent rainbow sheen that mimics an oil spill. Living at the air
water interface, these bacteria deposit a mixed film of iron oxides at the water surface, and the
light being reflected from this film interferes with the light being reflected from the water,
producing the misleading iridescent sheen (Patterson, 2006). When an iron oxide film is stirred,
however, it will break into randomly shaped platelets, while a petroleum spill that is broken up
will swirl back into itself and maintain an intact surface film (Antel, 2006).
The headwaters of Poplar Brook in Ocean Township have a unique yellow-ochre color for which
its dominant iron bacteria, Lepothrix ochracea, is named. The streambed below the dam at Rising
Sun Tavern Lake in Millstone looks like it is covered in tomato sauce, probably because the dam
footings opened up springs from the underlying Navesink Formation. Heavy iron leaching
impairs the ability of benthic organisms to survive in the flocculated sediment. The headwaters
of Shark River Brook in Wall channel through the glauconitic ironstone remnants of the Hominy
Hills; its streambed is heavily flocculated from the iron that is leaching from the peanut stone
that lines the streambank. In contrast, the springs of the adjacent tributary of the Shark River, the
Reevy Branch, originate below the ironstone ridges. Without the iron leaching, this boggy, teacolored
stream, flowing through light grey sand and gravel, has a completely different ecology.
The Reevy Branch is one of the few high quality (Non-Impaired) streams in this area of the
County, and supports a significant colony of the acid tolerant stonefly, Leuctridae.