Bacteria from horse farms and urban runoff had contaminated many of the shellfish harvesting beds in the downstream reaches of these rivers. Here, it empties into the Atlantic Ocean at Manasquan Inlet. Population centers include Point Pleasant, Howell Township, Freehold Township, Freehold Borough and Wall Township. The tides affect the Manasquan River up to a point approximately two miles east of the Garden State Parkway. Lead and possibly copper within the water column may impair aquatic life support at Squankum.
Sanitary quality is marginally poor.
As of 1994, all municipal wastewater facilities within the Manasquan watershed have been eliminated and their wastewater flows transferred to the Ocean County UA Northern facility for treatment and discharge to the Atlantic Ocean.