Despite years of monitoring levels of contamination at Goodie's Beach, as well as potential sources, it still is not known exactly where the contamination is coming from — except it's likely a human source.

A study presented by Bob Kennedy to Conservation Commission and select board members Feb. 12 revealed chemicals that are not naturally occurring have been found in a drain pipe that empties into Rockport Harbor near Goodie's Beach. According to Kennedy, carbamazepine, acetaminophen, caffeine and cotinine were detected in water coming from the drain pipe as well as Goose River, to a lesser extent. Carbamazepine is a seizure medication and cotinine is an "alkaloid found in tobacco that is also a metabolite of nicotine," meaning its been processed by a human body.

Amesbury Hill, Pleasant Street and Pascal Avenue share a common drainage area. Of 55 houses, 50 were inspected by Rockport Code Enforcement and no obvious violations were noted, Kennedy said. The remaining five houses were not inspected by the codes office, he noted.

"There's a good potential the source is human and we haven't found it yet," Kennedy said.

He said Goose River, which also discharges into Rockport Harbor, was considered as a potential source of contamination but eliminated as a major contributor.

"It seems reasonable to point the finger at the Goose River," Kennedy said. "But it may not be as simple as this."

He said the study showed during times of low salinity in the harbor, bacteria counts near the river also were low.

"This cast doubt on if the river is the primary cause," Kennedy said, adding later, "This drainage [pipe] is probably the primary source of contamination at the beach."

He said there have been a high number of advisories posted making people aware of potential bacteria in the water. During a PowerPoint presentation, Kennedy showed there were seven advisories posted in 2009, 10 advisories in 2010, five advisories in 2011 and the highest number — 11 — of advisories was posted in 2012.

"We've been listed as one of the most polluted beaches because of the advisories issued," he said.

Advisories are issued when levels of Enterococcus bacteria show levels of 61 MPN to 100 milliliters in freshwater and 104 MPN to 100 milliliters in saltwater, Kennedy said, adding Enterococcus bacteria is an indicator of other potentially harmful organisms in the water.

"Enterococcus bacteria can live in salt water and cold water up to 40 days," he said. "[But] it's really the other things that come with it we're concerned about."

Kennedy likened posting the beach as off limits due to bacteria levels to "warning people that were there yesterday." He said identifying and eliminating the source of contamination would allow for a more functional advisory warning system.

Several tests could help locate and/or eliminate the potential source of contamination. It was suggested a dye test or a smoke test might help locate the source, while extending the length of the drain pipe that emerges at Goodie's Beach into the harbor would help dilute any contaminants, Kennedy said. He encouraged continuation of water monitoring for bacteria levels regardless of other tests.

Michael Young, of public works, noted any environmental agency would require a solution addressing the source of contamination before issuing any permits for work to extend the drainage pipe.

"They're not gong to give us a permit to hide it," he said.

Camden Herald Associate Editor Stephanie Grinnell can be reached at 236-8511 or sgrinnell@courierpublicationsllc.com.