Eyes on the Rivers: Citizen Reports Lead to NJDEP Investigation

This May, COA received numerous reports from concerned citizens about fish kills and cloudy, brown water in the Navesink and Shrewsbury Rivers. The NJDEP was alerted and responded with an investigation. NJDEP Enforcement observed the fish kill and concluded that no sewage had been discharged into the river. With sewer malfunction ruled out, the NJDEP Bureau of Marine Water Monitoring conducted additional sampling and monitoring investigations on the Navesink River.  The NJDEP concluded that there is an algal bloom occurring in the Navesink River, consisting of Prorocentrum minimum at concentrations of 60,000 cells/mL. 

Algae blooms of this species are often called a “mahogany tide” due to the reddish-brown discoloration of the water. When these algae die off, it can cause low oxygen levels, potentially resulting in a fish kill. According to NJDEP, the fish kills being observed in the Two Rivers are routine this time of the year and typically caused by low oxygen levels.  Oxygen depletion can be triggered either by algal blooms or by overcrowding of fish in large schools in shallower waters.  The Navesink is not a primary recreational waterbody and does not fall under NJDEP’s CCMP bloom  monitoring protocol, and according to DEP, preliminary results indicate that this Prorocernum minimum may be non-toxic.  However, there are also reports that indicate that P.minimum could release hepatotoxins that are potentially toxic to fish.  COA is investigating more and will follow-up with updates.  To report water quality concerns to NJDEP, call 1-877-WARN-DEP.  COA also encourages citizens to share similar sightings via email (outreach@cleancoeanaction.org). 
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