Testing performed by Chopra-Lee Inc. of Grand Island, NY, a New York State accredited environmental analytical laboratory, has found PCB levels of nearly five parts per million in a guano/soil sample, a level exceeding state action levels for cleanup. Two mercury readings also exceeded state levels. The study was conducted during August 1999 and just released.

The concentration of toxic materials found in the soil and bird guano on Little Galloo Island appears to have bioaccumulated. Bioaccumulation occurs when chemically tainted fish are consumed in massive amounts by the glutinous double crested cormorant then deposited in the form of excrement, eggshell remnants and bird carcasses.

A recent article in The Wall Street Journal called attention to the fact that bioaccumulative chemicals (BCCs) including mercury and PCBs are still being dumped into areas called “mixing zones” in the Great Lakes and surrounding wetlands. BCCs from these mixing zones eventually permeate all waters of the Great Lakes, and the result of this contamination is that all species in the food chain are exposed.

Mixing zones and the dispersed contamination they cause lead to BCCs being collected by fish and bird species, which themselves become “accumulators.” Unlike fish, the cormorant accumulates toxic chemicals from hundreds of square miles of the lake, brings these chemicals back and deposits them in the form of guano on a few island acres.

“We are outraged that such a situation exists on state owned property. It is intolerable that state land contains concentrated BCC which during spring thaw and seasonal rains can leach into local waters, thus exposing area residents,” said the owners of the study, residents of Henderson, NY.

The Double Crested Cormorant (DCC) was first reported in the Lake of the Woods area of Ontario, Canada as early as the late 18th century. Recorded cormorant nestings were reported in Lake Superior in the 1920s. Breeding was reported on Lakes Erie and Ontario in the late 1930s. By the late 1940s and early 1950s, cormorant nesting pairs were in abundance in the eastern Lake Ontario region. In 1974, 22 pairs of cormorants were reported on Little Galloo Island.

From 1973 to 1991, their numbers increased more than 300-fold in certain areas of the Great Lakes. The dramatic increase in populations of the DCC was probably augmented by a rise in the numbers of smaller fish, such as rainbow smelt and alewife along with increases in the stocking of game fish such as salmonoides and bass by the NYSDEC and the Ontario Ministry of the Environment. In 1996, there were a reported 8,410 pairs of cormorants on Little Galloo island.

Studies recently completed by the NYSDEC have concluded that double crested cormorants consume significant numbers of smallmouth bass, greatly reducing the overall population. Current estimates of smallmouth bass consumption by cormorants exceed the number taken by anglers by 10-30 fold. The expanding cormorant populations have also displaced the Black Crowned Night Heron from Little Galloo Island and destroyed woody vegetation on the island favored by other colonial species.

Chopra-Lee, Inc. was retained by a group of homeowners in the Henderson Bay area to try and determine if the population explosion of the double crested cormorant over the last few decades may pose a health threat to the citizens of the area and/or the environment.

This project in Little Galloo Island was chosen because of the populations of cormorants that have existed on the island over the last twenty-five years.

Nearby Galloo Island was chosen as a background site because of the facts that cormorants have not established nesting on the island, the close proximity of the two islands and the island is of a similar geological makeup to Little Galloo Island. The background site will be sampled and analyzed for similar parameters to that on Little Galloo Island and the results will be used to compare the soil and surface water conditions.

Analytical Results/Findings

Soil/Guano

By far the most interesting and alarming discoveries of this investigation involve the soil and soil/guano samples that were obtained from Little Galloo and Galloo Islands. Analytical evaluation of the soil/guano samples from Little Galloo Island shows elevated levels of PCBs, mercury and DDE. PCBs, mercury and DDE were found in all four soil/guano samples that were obtained from Little Galloo Island. The soil samples from neighboring Galloo Island, which was used as a background-testing area, had no traces of either PCBs or the pesticide DDE. Some mercury was found in the soils from Galloo Island.

The PCB level of 4.78 mg/kg (ppm) for the guano/soil sample “S-2 top” that was obtained from beneath a dead tree trunk on the northeast side of Little Galloo Island, exceeds the recommended cleanup level for surface PCBs. Elevated levels of PCBs and DDE were found in all the remaining soil/guano sampled from Little Galloo Island but were within the recommended cleanup levels. The mercury readings from sample locations “S-2 top” and “S-2 bottom” exceeded the NYSDEC recommended cleanup objective level.

Surface Water

The surface water samples obtained from the Little Galloo and Galloo island areas (W-1 – W-8) showed a pattern of contamination around the island differing in the upwind and downwind locations.

The total bacteria samples from the two near shore and two off shore sampling sites of Little Galloo Island showed some expected results. Sample location W-4, which was located approximately 500 yards from the southwest shore (upwind) of Little Galloo Island, had a total bacteria count of less than 33. The other three sites from the Little Galloo Island area showed high total bacteria counts from both the near shore (14,600 and 10,133) and the downwind off shore (1,367) sampling sites.

The pool of standing water on the northwestern side of Little Galloo Island (sample W-3) showed an extremely high total bacteria count of 43,700 colony forming units.

The two residential groundwater wells sampled and analyzed as part of this investigation showed some interesting and contrasting analytical results. No pesticides or PCBs were found in the groundwater from either location. The total bacterial count of the groundwater at the residential house on Henderson Bay (W-10) had an elevated level of colony forming units (12,767) compared to the Jenkins residential house (W-9) where only 1,000 colony forming units were found. The 12,676 colony forming units are similar in number to the quantities found near Little Galloo Island. Additionally, elevated levels of nitrates, aluminum, calcium, iron, potassium and zinc were found in the groundwater sample from W-10 as compared to sample site W-9. Some of the results were over ten times higher in comparison.

Conclusions and Recommendation

This investigation has shown that the birds that roost on Little Galloo Island, especially the double crested cormorant have deposited toxic compounds like mercury, PCBs, and DDE on the island. The concentration of the toxic materials has bio-accumulated exponentially on Little Galloo Island, as compared to other islands in the area, due to the over population of cormorants.

The surface water sampling has shown that there is a potential correlation between Little Galloo Island and the downwind surface water quality. Total bacteria colony forming units downwind of the island (1,367) were higher than the upwind sampling location (<33). Although no PCBs, DDE or excessive levels of heavy metals were found downwind of Little Galloo Island, the levels of PCBs and DDE that were found on the island are a potential leaching source of surface water contamination during heavy rain or spring snow melt periods. An immediate area of concern involves the neighboring Galloo and Stony Islands where the potable drinking water source for the inhabitants of the islands is the water from Lake Ontario. There is a potential for the potable water sources of the neighboring islands to be adversely affected by surface runoff from Little Galloo Island. The surface waters of the Henderson Bay and other mainland areas are potentially vulnerable to runoff from Little Galloo during periods of excessive rain and/or snowmelt.

It is evident from this investigation and data resulting from other assessments performed in the area, that the over population of the double crested cormorant on Little Galloo Island has had an adverse effect on the ecosystem of the area. All efforts should be made in the future to control the population of the double crested cormorant and to keep the populations away from the other uninhabited islands in the area, especially the other islands and/or mainland areas, which are populated by humans. The release and accumulation of bird excrement and dead cormorant carcasses appear to be a direct threat to human health and the surrounding environment. Human access to Little Galloo Island should be limited and the island should be posted to warn any visitors about the chemical hazards associated with the island. If the population of cormorants on Little Galloo Island are not reduced or kept in check, the amount of contamination being deposited on the island will most likely only get worse over time.