Looks like excess lawn fertilizer may be the culprit, here the story from todays cbs2ny web site.
http://cbsnewyork.com/njnews/NJ--TheBlob-jn/resources_news_html
Excess fertilizer yields lagoon bloom
Thursday August 21, 2003
LITTLE EGG HARBOR TOWNSHIP, N.J. (AP) Ocean County health officials have warned residents that using too much lawn fertilizer may give rise to algae-like blobs in area lagoons.
Robert J. Ingenito, the county's environmental health coordinator, said an algae bloom that developed in a Little Egg Harbor Township lagoon this month was probably created by water runoff containing excessive fertilizer.
The mass is considered unusual because algae blooms do not typically look like blobs. State tests confirmed the clear mass was algae.
It was also examined by environmental consultant John Zingis who was part of the team that partially removed the mass from the lagoon on Aug. 11.
Nutrient-rich water and low oxygen levels create favorable conditions for large algae blooms, said the county health department.
Algae needs light, carbon, nitrogen and phosphorus to grow. Nitrogen can come from other plants or fertilizer, but ``phosphorous comes directly from fertilizer,'' said.
(Copyright 2003 by The Associated Press. All Rights Reserved.)