Environment

Sabbathday Lake Invasive Plant Patrol

| by Carol Gillis | Each summer and fall, volunteers all over Maine conduct surveys of lakes and great ponds to provide early detection of invasive aquatic plants. Invasive plant […]

| by Carol Gillis |

Each summer and fall, volunteers all over Maine conduct surveys of lakes and great ponds to provide early detection of invasive aquatic plants. Invasive plant species have been detected in several lakes and great ponds in Maine, including those near Sabbathday Lake. (See map here and DEP’s invasive aquatic species site here.)

Invasive species can be spread from an infested body of water to other lakes and streams by boats, motors, trailers, fishing gear, and anchors carrying small bits of invasive plant material, so all lakes and streams are at risk.  Even small pieces of these plants can grow rapidly into an ecologically and economically disastrous infestation.  The best prevention is for everyone moving boats or gear from one body of water to another to make sure everything is completely free of all plant material.

Most people are familiar with treating swimming pools with chemicals to remove algae, and some assume that the same type of treatment can apply to lakes.  This is not true!  After an invasive species is established, eradication is extremely difficult and costly and often may not be possible.  The purpose of conducting Invasive Plant Patrols is to detect invasive plants as early as possible to provide the best chance of containment or eradication.

In New Gloucester, 21 dedicated volunteers, led by Michael Cloutier, conducted a thorough invasive plant survey of Sabbathday Lake this year. All areas of the lake where plant growth can occur were checked.  For the survey the lake is divided into 25 sectors.  Volunteers survey one or two sectors at a time convenient for them.  It usually takes several hours.  In 2019, the Sabbathday Lake Invasive Plant Patrollers donated 258 hours of time in training, surveys, and documentation.  Volunteers are trained and certified by Lake Stewards of Maine.

The Sabbathday Lake Invasive Plant Patrol was formed in 2011 and now includes 18 certified plant patrollers.  As of the 2019 survey, 47 species of native aquatic plants have been identified.  No invasive plants have been observed to date.  Along with invasive plant patrols, boat inspections are an important part of prevention, and those inspectors undergo a separate training program.

The health of Sabbathday Lake is important for its beauty, for the wildlife it supports, and for recreation.  It even has a role as a state fishery, as smelt eggs from Sabbathday Lake are sometimes used to stock other lakes in the state.   

In addition to the invasive plant survey, the lake is tested throughout the summer for water clarity using Secchi disc readings.  The last reading, taken on September 10th, indicated water clarity to a depth of 8 meters, which is typical for Sabbathday Lake but is above the average for most lakes in Maine.

Variable water-milfoil (invasive) | Photo: Carol Gillis
Curly-leaf pondweed (invasive) | Photo: Carol Gillis