Farm Pond FAQ

What type of lake is Farm Pond?
Farm Pond is a “kettle” lake, meaning it was formed by the melting remnant of one of the glaciers that departed from New England more than 12,000 years ago. The pond is about 58 feet at its deepest and covers about 125 acres. Farm Pond has no major stream tributary, so its surrounding watershed land area is quite small relative to the size of the lake, helping to maintain excellent water quality most years. The terms "oligotrophic" and "mesotrophic" refer to trophic states (relative nutrient levels), and have nothing to do with geological periods.

Why is water quality important?
Farm Pond supports a wide variety of plant, fish, and wildlife species. Good water quality is essential for the survival and health of these species. Poor water quality can lead to a decrease in biodiversity, and impairments to recreational use by all of us. Farm Pond has been experiencing the last few years some decrease in water quality, as seen by the declining water clarity drop off in 2022.

What impact do boats have on the pond?
The simple act of washing a non-motorized boat/kayak/paddle board etc. before entering Farm Pond plays a critical role in ecological conservation efforts. It helps prevent the spread of invasive aquatic plant species that may have been picked up in other water bodies. Many lakes and ponds in our area are heavily infested with invasive non-native aquatic plants or weeds and we want to protect Farm Pond from such problems. A boat wash station is maintained for this purpose in the parking lot and is required to be used for all watercraft entering Farm Pond at the boat ramp. Property owners along the lake are requested to take similar precautions.

What routine water testing is done at the Town beach? 
Per MA Dept of Public Health requirements for public beaches, the Select Board's office arranges for weekly testing of the water at the Town beach weekly during the season the lifeguards are on duty for the common bacteria known as "E coli", or Enterococci. This serves as a simple screening test for more dangerous "fecal indicator bacteria (FIB)". Weekly results are reviewed by our Board of Health. Normally well below MA DPH limits, the beach is occasionally closed due to high E coli values, most commonly near the end of the season when geese start to congregate at night on the beach. Whenever these occurences happen, postings are made on the Town website and signs at the parking lot entrance.

What is an "algae bloom"?
An "algae bloom" is broad term referring to a a rapid increase in the population of various microscopic planktonic organisms (including green algae, blue-green cyanobacteria, diatoms, etc.) in water systems, often resulting in a visible change in the water's color and a decrease in water clarity. This can occur in freshwater and marine environments and is usually promoted by excess nutrients (like phosphorus and nitrogen) in the water.

What is a cyanobacteria bloom and how does it differ from algae?
These large water appearance changes, or blooms, may be caused by an excess of several different types of microorganisms. Of most concern at Farm Pond is the recent history of "harmful cyanobacteria blooms" or HCB's, which involve various species of cyanobacteria, one of the oldest families of life on our planet. Cyanobacteria have always existed in Farm Pond, but larger blooms were only first observed in July of 2019. Unlike the different microorganism family of "green algae", cyanobacteria can at times produce certain toxins harmful to humans, pets, and wildlife. These blooms may look like green, blue-green, or red paint on the water's surface and can at times produce a foul smell. The two terms harmful cyanobacteria bloom HCB, and harmful algae bloom HAB, are often used to describe any unsightly bloom/scum appearing at the water surface.

Can I swim in the pond when there are HCB/HAB (harmful cyanobacteria blooms/harmful algae blooms) blooms? 
It depends on the particular bloom. In many cases, it is fine for humans to swim in the pond, but you should avoid having your dogs near the pond and keep them from drinking the water. Given the large size of Farm Pond (125 acres), and the very transient behavior of HCB/HAB blooms (wind action, short time periods of bloom, etc.), and our inability to test routinely for cyanotoxins, this is a challenging question. Best to check with the town's Board of Health if you have particular concerns. General advice is to avoid ingesting the water and avoid swimming (including pets) near any areas with bloom appearances.

How can I control cyanobacteria and algae growth in the pond?
Maintaining a balanced ecosystem can reduce excess cyanobacterial and algae growth. This includes the limiting of nutrients entering Farm Pond. Some major nutrient sources include: runoff from surrounding areas (e.g., fertilizers, animal wastes, detergents, automotive fluids, etc), soil erosion at areas along the lake, and septic systems within the watershed.

Why have I seen dead fish occasionally at Farm Pond?
During the 2023 season, many dead fish of varying types were seen in the pond, a much larger number than any recent year. Our investigation revealed that the cause of this mass mortality event was multifactorial, with parasitism potentially leading to the fish kill. Combined with water quality alterations, these conditions permitted bacterial colonization, particularly in the younger fish. Water quality was reported to be within normal limits during this summer, though temperatures had been higher than usual, and the area had recently received excessive rainfall. None of these findings indicated anything that could be harmful to humans recreating in the pond.

What should I know about eating the fish at Farm Pond?
The Massachusetts Department of Public Health advises against consumption of fish caught anywhere in freshwater bodies in Massachusetts, including Farm Pond, particularly to vulnerable human populations (pregnant and nursing mothers, children, etc.). Contaminants of local freshwater fish include mercury, pesticides and other chemicals (PCB, PFAS). "Catch and Release” is really the safe way to go.

What types of wildlife can be found around the pond?
Ponds support diverse ecosystems, including various species of birds, amphibians, reptiles, and mammals. Common examples include ducks, geese, eagles, herons, loons, turtles, and frogs.

What are the benefits of having aquatic plants in the pond?
Aquatic plants provide oxygen, absorb excess nutrients, provide habitat for fish and wildlife, and help stabilize the pond's ecosystem. Farm Pond exhibits a very healthy mix of native aquatic plants at this time.

How can I maintain the aesthetic appeal of the pond's shoreline?
Leave it to nature! If needed to prevent erosion, consider planting native vegetation. Native plants help stabilize the soil, provide habitat for wildlife, and filter runoff pollutants.

Are any regulations or permits required to modify the shoreline area or construction near the pond?
Any changes considered within 100 feet of the Farm Pond edge, including surrounding wetlands, should be first discussed with the Sherborn Conservation Commission for any required reviews and approvals.

How can I help preserve Farm Pond?
Please visit our How You Can Help page.