7077-R2_NewGloucester_2019_AnnualReport_Web

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SABBATHDAY LAKE | 2018 Water Quality Report

Lake is considered above average since monitoring began in 1975 (Lakes of Maine, 2015). However, Sabbathday Lake is sensitive to pollutants in stormwater runoff from the watershed. Significant amounts of stormwater runoff can temporarily reduce water clarity and, if erosion in the watershed increases, long-term degradation in water clarity can become extremely difficult to reverse. METHODS FB Environmental Associates, with assistance from Ecological Instincts and SDLA volunteers, collected water quality data at the deep spot (Station 1) of Sabbathday Lake on three sampling days in 2018 (July 17, August 21, and September 14). Sampling was conducted in accordance with standard methods and procedures for lake monitoring established by the Maine Department of Environmental Protection (Maine DEP), the U.S. Environmental Protection Agency (USEPA), and the Maine Volunteer Lake Monitoring Program (VLMP). All water samples were analyzed at the Health and Environmental Testing Lab (HETL) in Augusta. An integrated epilimnetic core, or a core of water taken from the surface of the lake to the upper part of thermocline, was collected at the deep spot (Station 1) of Sabbathday Lake during each sampling event. Due to thermal stratification, the depth of the core sample (or upper part of the thermocline) varied throughout the season. Parameters measured included Trophic State Indicators (i.e., water clarity, TP, and Chl-a), DO and water temperature profiles, true color , total alkalinity, and pH . is si r r si it ri ( s f i , ). r, t is s siti t l t ts i st r t r r f fr t t rs . i ifi t ts f st r t r r f t r ril r t r l rit , if r si i t t rs i r s s, l -t r r ti i t r l rit tr l if i lt t r rs . ir t l ss i t s, it ssist fr l i l I sti ts l t rs, l t t r lit t t t s t ( t ti ) f t t r s li s i (J l , st , t r ). li s t i r it st r t s r r s f r l it ri st lis t i rt t f ir t l r t ti ( i ), t . . ir t l r t ti ( ), t i l t r it ri r r ( ). l t r s l s r l t t lt ir t l sti ( ) i st . i t r t ili ti r , r r f t r t fr t s rf f t l t t r rt f t r li , s l t t t s t ( t ti ) f t ri s li t. t t r l str tifi ti , t t f t r s l ( r r rt f t t r li ) ri t r t t s s . r t rs s r i l r i t t I i t rs (i. ., t r l rit , , l- ), t r t r t r r fil s, tr l r , t t l l li it , . i

Chlorophyll-a (Chl-a): a measurement of the green pigment found in all plants, including microscopic plants like algae. It is used as an estimate of algal biomass; higher Chl-a equates to greater amount of algae in the lake. l - ( l- ): s r t f t r i t f i l l ts, i cl i icr sc ic l ts lik l . It is s s sti t f l l i ss; i r l- t s t r t r t f l i t l k . l r

Trophic State Indicators are indicators of biological productivity in lake ecosystems, including water clarity, total phosphorus, and chlorophyll-a. The combination of these parameters helps determine the extent and effect of eutrophication in lakes, and helps signal changes in lake water quality over time. True Color measures the influence of suspended and dissolved particles in water from weathered geologic material, vegetation cover, and land use activity. Colored lakes (>25 PCU) can have reduced water clarity and increased phosphorus concentrations. Total Alkalinity: A measure of the capacity of water to neutralize acids (i.e., buffering capacity). Total alkalinity above 20 ppm buffers against drastic changes in pH that could impact aquatic plants and animals. pH: a measure of the acidity of a solution on a scale of 0-14. Most aquatic species require a pH between 6.5 and 8.0. r ic t t I ic t rs r i ic t rs f i l ic l r ctivity i l c syst s, i cl i t r cl rity, t t l s r s, c l r yl - . c i ti f t s r t rs l s t r i t xt t f ct f tr ic ti i l k s, l s si l c s i l k t r lity v r ti . r l r s r s t i fl c f s s iss lv rticl s i t r fr t r l ic t ri l, v t ti c v r, l s ctivity. l r l k s ( ) c v r c t r cl rity i cr s s r s c c tr ti s. t l l li it : s r f t c city f t r t tr liz ci s (i.e., f ri c city). t l lk li ity v f rs i st r stic c s i t t c l i ct tic l ts i ls. : s r f t ci ity f s l ti sc l f - . st tic s ci s r ir t .5 .0.

Sabbathday Lake is a mesotrophic lake and has intermediate levels of phosphorus and chlorophyll-a and water clarity between 4 and 8 meters depth. and water clarity between 4 .

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