Water Testing & FAQs


Updated August 28, 2020

The E. coli and fecal coliform levels in Crystal Lake are within normal limits, according to the most recent water sample collected 8/26/20 and reported on 8/27/20.

Previous water samples taken July 1, August 5 and August 12 exceeded acceptable bacteria levels at a freshwater beach. Crystal Lake is tested for E. coli and fecal coliform. The accepted level of E. coli for a single sample is 235 cfu/100 ml or below. The accepted level of fecal coliform is 200 cfu/100 ml or below. (CFU stands for colony-forming units, the unit of measure used for samples like this.)

Samples are collected weekly, usually on Wednesdays. Results will be posted when available -- usually on Fridays.

Marine and freshwater beach guidance (MDPH)




Crystal Lake

July 1

Crystal Lake

July 3

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July 8

 Crystal Lake July 15

 Crystal Lake

July 22

 Crystal Lake

July 29

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August 5

Crystal Lake 

August 6

 Crystal Lake August 12 Crystal Lake August 13  Crystal Lake August 19   Crystal Lake August 26 

E. coli

235 cfu/100 ml

Above 1600 cfu/100 ml

72 cfu/100 ml

136 cfu/100 ml

 10 cfu/100 ml  20 cfu/100 ml 108 cfu/100ml  Above 600 cfu/100 ml  152 cfu/100ml Above 1000 cfu/100 ml  156 cfu/100 ml


cfu/100 ml



cfu/100 ml


Fecal Coliform

200 cfu/100 ml

Above 1600 cfu/100 ml

88 cfu/100 ml

128 cfu/100 ml

 15 cfu/100 ml  48 cfu/100 ml  128 cfu/100 ml Above 600 cfu/100 ml
 168 cfu/100ml  Above 1000 cfu/100 ml  124 cfu/100 ml


cfu/100 ml



cfu/100 ml




Frequently Asked Questions

Should I swim in Crystal Lake if bacteria levels exceed acceptable limits?

No one – people or pets -- should have contact with the water when bacteria levels exceed acceptable limits. 

Recreational activity in water with bacteria that exceed these limits can cause gastrointestinal symptoms such as nausea, vomiting, diarrhea, and abdominal pain, respiratory symptoms like sore throat, cough, runny nose, and sneezing, eye and ear symptoms including irritation, earache, and itchiness, dermatological symptoms like skin rash and itching, and flu-like symptoms such as fever and chills. Most of these symptoms are minor most of the time but can occasionally be more serious, especially in sensitive populations (e.g. immuno-compromised children and elderly).

What are the sources of bacteria in the water?

Bacteria may be present in the water due to a variety of sources. Rain is often a contributing factor to beach water pollution. As rainwater washes over land, it can carry bacteria to the beach. Sewage entering the water can also contribute to high bacteria levels.

What about animal wastes on the beach?

Animal waste, such as from dogs or birds, can get into the water and negatively affect water quality at beaches. The bacteria in dog and bird waste can elevate bacterial levels which can lead to beach postings. Properly cleaning up after your pet can lessen the likelihood of your pet's waste contaminating the beach water. Similarly, refraining from feeding birds at beaches should help reduce potential bacterial contamination.

What is E. coli and fecal coliform?

These are indicator bacteria – bacteria that indicate the presence of fecal contamination. E. coli stands for Escherichia coli, a species of fecal coliform bacteria that is specific to fecal material from humans and other warm-blooded animals. E. coli is a single species in the fecal coliform group. Indicator bacteria testing is recommended for freshwater recreational swimming areas.

Is this the same thing as the cyanobacteria problem from last summer?

No, cyanobacteria are microorganisms similar to algae, not fecal matter. https://www.mass.gov/guides/cyanobacterial-harmful-algal-blooms-cyanohabs-water

Where can I get more information?

The above information was adapted from these resources you may find helpful if you would like more information.





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