Algae And Temperature Drop Suspects In Mill Pond Fish Kill

By Andrea Aurichio | 1 Comment

Mill Pond experienced a mysterious fish kill when thousands of dead fish suddenly floated to the surface of the water two Mondays ago, including catfish, white perch, eels and bass. Photos by Christine Bellini

Water Mill - The mystery of the Mill Pond fish kill remains unsolved as Southampton Town Trustees continue their investigation this week into one of the largest environmental mishaps ever to have occurred at the 92-acre pond in recent history. Thousands of dead fish unexplainably floated to the surface of the otherwise tranquil pond that feeds into Mecox Bay.

Long-time pond front residents were shocked and alarmed to witness catfish, white perch, eels and bass by the hundreds float to the surface two Mondays ago. Many had originally attributed the dramatic kill to storm water run-off, chemical pollutants and poor management of the natural resources that have affected the water quality of the pond.

The Trustees seemed to be getting closer to a more definitive theory concerning the fish kill as they convened for the regular monthly meeting Monday. A consensus among the Trustees is leaning towards the overwhelming growth of algae in the pond that resulted in a rapid deoxygenation as temperatures dropped rapidly overnight Monday, Sept. 22.

Water Mill resident Steve Abramson joined in the discussion concerning the ecological
health conditions of Mill Pond. Photo by Andrea Aurichio

"We are trying to put something together quietly," Trustee Fred Havemeyer said. "We have been very upset about this fish kill for the last few weeks. This board has spent hours trying to figure out what happened. We haven't gotten to the bottom of it yet, but we will. We have not publicized this because we did not want to get into a big brouhaha."

"Nothing like this has ever happened before," Trustee Chairman Jon Semlear commented, "we are looking at this on every front."

The town has enlisted the help of environmental consultants specializing in pond life to study water conditions at the pond as well as take a closer look at plant and fish life hoping to restore and preserve the pond's fragile ecological balance.

James Walker, of Interscience, an environmental consulting agency, addressed the Trustees on Monday, while Dr. Chris Gobler, of Stony Brook University's Southampton College previously pointed to the high percentage of blue green algae in the pond as a possible cause of the massive kill.

This week Walker outlined a multi-faceted approach to the problem suggesting the town begin water quality testing at the pond in addition to checking for the presence of such nutrients as phosphorous and nitrogen. "We need to hire a specialist to come in and take a look at this," Walker suggested.

Havemeyer noted he had coincidentally been at dinner at a friend's house located on the shores of Mill Pond just a few days before the fish kill. "The water was green as grass," Havemeyer recalled, referring to the high concentration of algae growing in the pond, "then the temperatures dropped. A few days later the fish kill occurred."

Local residents pointed to the existence of brown vegetation along the shores of Mill Pond, suggesting the possible presence of toxic chemicals or other pollutants that may have been dumped into the pond. The use of fertilizers by pond front residents, some of whom cultivate extensive waterside gardens, was mentioned as potentially adversely impacting the water quality as well. In recent years, as awareness has risen concerning the health of the pond, residents have been encouraged to plant vegetative barriers to stop the considerable run-off from lawns from entering spilling into the pond.

Southampton Town Trustees advanced their theories concerning the fish kill at Monday's meeting with concerned Water Mill residents. Photo by Andrea Aurichio

Community activist Steve Abramson, who lives along the pond, appeared before the Trustees at Monday's meeting seeking more active legislation to control storm water run-off which is also believed to be a major source of pollution in this an other lakes and ponds throughout the trustee's jurisdiction.

"There is massive legislation underway to address the storm water run-off issue," Katie Garvin, a town attorney who frequently sits in on Trustees meetings, informed the session.

The Trustees acknowledged these concerns while noting a toxic incident would have killed all the fish in the pond including the carp and the goldfish that appear to still be thriving a few weeks after the incident and the pond remains "as green as grass" to even the most casual bystander.

The presence of the carp and the goldfish also pose a problem of sorts for the health of the pond. "The carp and the goldfish stir up the bottom," Semlear said, "and that is not good." The Trustees discussed the possibility of controlling these two fish populations by harvesting the carp and the goldfish and possibly selling them at the Fulton Fish Market in New York City.

The Trustees did not advocate the dredging of the pond, another suggestion advanced by area residents, noting dredging would stir up sediments on the bottom. A plan to remove water lilies from the pond suggested by Abramson's committee of concerned residents also met with resistance. "That is not the best thing to do," Havemeyer countered, noting water lilies are a protected native species that also provide shade for the pond bottom and enhances aquatic life.

Water lilies were selectively hand-harvested from a small section of Lake Agawam in the heart of Southampton Village that is also overseen by the Trustees. "That was in a small cove of the lake," Havemayer pointed out, making the distinction. In comparison, Mill Pond has large sections covered with water lilies. "It's not the same," he said.

"The Department of Environmental Conservation would not go along with that either,' Semlear noted.

The Trustees did not advocate the dredging of the pond, another suggestion advanced by area residents, noting dredging would stir up sediments on the bottom.

Health Of Pond Source Of Concern
The ecological condition of Mill Pond has been a source of concern for more than two decades, although the pond has never been the site of a massive fish kill during that time.

"Last week, one of the largest blue green algae blooms ever recorded in Mill Pond occurred," Gobler wrote in an email sent to the trustees on Sept. 22. "Today, the largest and only fish kill we have ever observed in Mill Pond occurred." Algae blooms occur as a result of an excess of nutrients in the water, particularly phosphorous.

Excess carbon and nitrogen are also frequently suspected as causes for algae blooms of various colors but prevailing research seems to dispute this contention in this case.

When phosphates are introduced into a water system in high concentrations, the growth of algae and other plants increases. Eventually the algae takes over, killing many other aquatic plants creating an ecological imbalance. The dead organic matter becomes food for bacteria that decomposes it. With more food available, the bacteria increases and begins to use up the dissolved oxygen in the water.

When the dissolved oxygen content decreases many fish and aquatic insects cannot survive. The result is a fish kill basically resulting from the conditions where fish can no longer breathe in the water.

Dr. Gobler contends that a lack of oxygen caused by the algae bloom may have caused the fish kill, although he remains uncertain as more inquiries are made. Gobler has ruled out local speculation concerning run-off as the cause of the fish kill. After monitoring rainfall patterns for the month, Gobler concluded it was highly unlikely that toxic run-off affected the fish in this pond.

The clean-up has been arduous as town workers scooped the dead fish out of the pond for nearly a week and transported the organic matter to the town's landfill.

In 2007, a group of residents joined together and raised $90,000 to buy "bubblers" or aeration devices to increase water circulation at the pond. The bubblers, referred to as Solar Bees, are solar-powered water stirring devices that literally move water around in the pond.

The Solar Bees were removed from the pond a few weeks ago to be stored in Hampton Bays at the Town Trustees facility for the winter months. Semlear does not believe the removal of the bubblers caused the asphyxiation of thousands of fish that floated to the surface of the pond as it has been their practice in the past to remove them after the summer months.

The clean up has been arduous as town workers scooped the dead fish out of the pond for nearly a week and transported the organic matter to the town's landfill. The exact number of dead fish remains unclear but is estimated to amount to thousands of pounds of fish.

"It was a big job, " Jim White said, noting that one landscaper had approached him but was unable to take some of the dead fish off his hands for use as fertilizer because all his equipment was tied up at job sites. "So he couldn't do it," White reported. "The Pond looks good today," White added.

"We are all over this," Semlear asserted. "Our job is to protect these waters and preserve them for future generations."

For more information, click here.