‘Swimmable Shore’ bacteria monitoring program

Dorchester Banner
Posted 8/4/19

EASTON - “Is it safe to swim in the water?” This is a common question ShoreRivers gets asked throughout the summer months when members of the community are hoping to find a refreshing place to …

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‘Swimmable Shore’ bacteria monitoring program


EASTON - “Is it safe to swim in the water?” This is a common question ShoreRivers gets asked throughout the summer months when members of the community are hoping to find a refreshing place to cool off from the seasonal heat. To better answer this question, and to identify potential pollution hotspots, ShoreRivers runs a seasonal bacteria monitoring program.

ShoreRivers and its partners monitor 28 sites where people frequently come in contact with water, including swimming locations, marinas, yacht clubs, and towns. They monitor weekly or bi-weekly from Memorial Day to Labor Day and before holiday weekends.

By collecting, analyzing and distributing data on bacteria levels in the river ShoreRivers aims to provide the public with the information they need to make educated decisions about their contact with the water.

Tips For Safe Swimming
There are inherent risks associated with coming in contact with river water, but you can lower your risk by following these guidelines and staying informed about the current health of your river.Check Swim Guide for current information.

Do not swim within 48 hours of a major storm event. A major storm event is any storm that creates runoff, which provides a vehicle for bacteria to be transported from our land to our rivers.

Do not swim if you have open wounds, scratches, skin lesions, an ear infection, or a comprised immune system.

Do not swallow river water.

Always shower or rinse off after swimming in open water.

When in doubt, stay out. Never swim in cloudy or murky water, or if the water has an odd smell or appearance described as being more green or more brown than usual. Avoid areas where oilslicks, fish kills, or ‘scum’ is visible in the water.

Sampling Protocol
ShoreRivers follows EPA’s standard protocols for collecting and analyzing samples for enterococci, a type of bacteria commonly found in human and animal waste. Enterococci can enter our rivers when rain washes it in from failing septic systems, animal fertilizer off farm fields, livestock waste, sewer spills or overflows, pet waste, or wildlife.

The protocol uses a pass/fail system to determine if enterococci levels are safe or unsafe for swimming. For a single sample taken at one location, 104 MPN* /100 ml is the threshold used to determine if the concentration meets acceptable swimming levels. Maryland regulations identify this threshold to determine safety at designated swimming beaches throughout the state (Code of Maryland Regulations26.08.09.01).

At a site where three or more samples are collected at once, a geometric mean is calculated and 35 MPN/100 ml is used as the threshold for safe swimming. (MPN = Most Probably Number of enterococci colonies.)

Community Partners
The Swimmable Shore Rivers Bacteria Monitoring Program is made possible by the support from community partners and trained citizen scientist including: Dorchester Citizens for Planned Growth (DCPG); Dorchester County Tourism; Dorchester County Parks and Recreation; Trained Citizen Scientist Volunteers.

If you are interested in learning the latest results from the bacteria monitoring, visit www.swimguide.orgor follow #swimmableshorerivers on Facebook or lnstagram.

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