Beach Program Water Quality Standards
The exceedance criteria, or level at which a sample fails, is 104
Enterococci bacteria per 100 milliliters of sample water, or Enterococci levels
exceed the geometric mean of 35 counts of Enterococci per 100 mL of water in at
least five samples collected over a 30-day period. This is one consideration
for placing advisories at the beach. For the other considerations for advising
against recreational water activities or for closing a beach click on How Beach
Advisories are Determined.
The Maine Healthy Coastal Beaches Program is providing the State of
Maine with a system to monitor public beaches and notify the public when there
is a potentially hazardous condition.
The Maine Healthy Coastal Beaches Program ensures healthy, informed
opportunities for swimming and other recreational water activities along the
coast of Maine. Monitoring coastal water quality for swimming and other water
contact usage is the responsibility of the local jurisdiction. It is not a
mandated requirement from the State, nor does the State of Maine monitor public
beaches other than those of their ownership.
Maine has 46 public beaches and recreational waters on its coast,
of which 36 of these are participating in the Maine Healthy Coastal Beaches
Program. The Maine Healthy Coastal Beaches Program is currently monitoring
these waters, educating the public about potential health risks at these
waters, and notifying the public when a disease-causing microorganism is
present and may pose a health risk.
Maine’s Healthy Coastal Beaches Program will provide a current list
of coastal beach advisories from participating towns/State Parks throughout the
state. To view current beach advisories, go to Today’s
The towns and State Parks currently post beach advisories when
sample analyses result in bacteria levels above the state standard, and the
conditions warrant it, indicating the possible presence of disease-causing
organisms. These advisories are recommendations to the public to avoid water
contact activities at the beach until further analyses reveal safe conditions.
A decision to close or post beaches is based upon a
Risk-Based Assessment Matrix tool to beaches for ongoing management
Beaches are not “closed” simply on the exceedance of the
bacterial count, but on the Risk Assessment Matrix factors which includes
bather numbers, time of last rainfall, and history of known problems. This is a
coordinated decision between the Beach Manager, Program Coordinator, and State
The town/State Park beach managers may use their own discretion to
actively close a beach to the public. The municipality/State Park must notify
the Maine Healthy Coastal Beaches Program of their intentions to close or put
up an advisory at a particular beach by indicating this on the on-line
The Healthy Coastal Beaches Program has produced a sign with attachments for
advisory or closure to indicate a beach advisory.
Click here to view samples of the signs.
What Is The Geometric Mean?
Many wastewater dischargers, as well as regulators who monitor
swimming beaches and shellfish areas, must test for and report fecal coliform
bacteria concentrations. Often, the data must be summarized as a "geometric
mean" (a type of average) of all the test results obtained during a reporting
period. Typically, public health regulations identify a precise geometric mean
concentration at which shellfish beds or swimming beaches must be closed.
A geometric mean, unlike an arithmetic mean, tends to dampen the effect of very
high or low values, which might bias the mean if a straight average (arithmetic
mean) were calculated. This is helpful when analyzing bacteria concentrations,
because levels may vary anywhere from 10 to 10,000 fold over a given period.
How do you calculate a geometric mean? The easiest way to think of the
geometric mean is that it is the average of the logarithmic values, converted
back to a base 10 number.
However, the actual formula and definition of the geometric mean is that it is
the n-th root of the product of n numbers, or:
Geometric Mean = n-th root of (X1)(X2)...(Xn)
Where X1, X2, etc. represent the individual data points,
and n is the total number of data points used in the calculation.
Geometric Mean of
Click For more
information on the Geometric Mean.
I know if it’s safe to swim at my local beach?
There are several ways to determine whether it’s safe to swim at a
Check the Today’s Beach Status to see
if the beach is listed. For further information,
contact the Maine Healthy Coastal Beaches Program.
Contact the local beach manager for that town or State Park. Staff will be able
to give you information on whether the beach is part of the Healthy Coastal
Beaches Program and if water quality is monitored at that beach.
Look for any
advisory/closure signs or other signs posted at the beach entrance or
on the lifeguard stands. If there are no advisories (orange) or closures (red)
posted, but there is
an open (green) sign, this will indicate that this beach is open
Contact your local health official. A health official may be able to inform you
whether a beach advisory has been posted at the beach you plan to visit.