POCASSET LAKE

Town	County	Delorme Map #	True Basin	Flushing Rate	Elevation
WAYNE	KENNEBEC	12	1	8.46 flushes/yr	284 ft

Maximum Depth	Average Depth	Surface Area	Lake Volume	Drainage Area
6 m (20 ft)	4 m (13 ft)	229 ha (566 ac)	8,911,998 m³ (7,225 ac-ft)	11 km² (4.2 mi²)

Pocasset Lake lake type: Coastal Shallow Lake

Secchi Disk Transparency Plots

Temperature & Dissolved Oxygen Profiles

Most recent late summer (Aug. 1 - Sept. 7) temperature and dissolved oxygen profile plots

Temperature and Dissolved Oxygen profile Contour Plots
Displayed only for lakes with profile data collected in at least 5 months from May - Oct.

Temperature and Dissolved Oxygen Profile Data

Late summer only (Aug. 1 - Sept. 7); limited to eight most recent profiles

Units: Temperature (TEMP) = °C; Dissolved Oxygen (DO) = mg/L

	2019-09-03		2020-08-23		2021-08-12		2021-08-25		2021-09-08		2022-08-03		2022-08-19		2022-09-01
Depth (m)	TEMP	DO	TEMP	DO	TEMP	DO	TEMP	DO	TEMP	DO	TEMP	DO	TEMP	DO	TEMP	DO
0	24	8.2	24	8.1	26	8.3	22	8.1	27	8.2	27	7.8	25	7.6	22	8.3
1	24	8.1	24	8.1	26	8.3	22	8.1	26	8.2	26	8.0	25	7.6	22	8.2
2	24	8.1	24	8.1	26	8.2	22	8.0	26	8.2	25	7.6	24	7.5	22	8.1
3	24	8.0	24	8.1	26	8.1	22	8.0	25	8.1	24	7.6	24	7.5	22	8.1
4	24	8.0	24	8.0	26	8.0	22	8.0	25	8.0	24	7.5	24	7.4	22	8.0
5	24	7.9	24	8.0	26	7.2	22	7.9	24	5.4	23	5.9	24	7.2	22	8.0
6	24	7.8	24	8.0	25	4.3	22	7.9	23	2.7	22	3.9	24	6.7	22	7.7

Trophic and Chemistry Summary Values

See below for table legend

Avg Color	Avg Alk	Avg Cond	Avg pH	Avg TP EC	Avg TP SG	Avg TP BG	Avg TP PG	SDT Min	SDT Avg	SDT Max	Chl Min	Chl Avg	Chl Max
14	14	57	7.2	9.3	7	10		4.2	5.7	6.6	1.5	3.4	13

Plot Legend: Solid color bars = parameter ranges for most Maine lakes; horizontal thick black line: mean value for all Maine Lakes; Striped pattern = expected range for Coastal Shallow Lakes; white diamonds: mean values for Pocasset Lake.

Trophic and Water Chemistry Data

**Table Legend:**

**Color**: Color (SPU), **Alk**: Alkalinity (mg/l CaCO₃), **SpCon**: Specific Conductivity ( $\mu$ S/cm), pH: pH (standard units)

TP = Total Phosphorus ( $\mu$ g/L) – EC: Epilimnion Core, SG: Surface Grab, BG: Bottom Grab, PG: Profile Grab

**SDT** = Secchi Disk Transparency (m) – **Min**: minimum value, **Avg**: average value, **Max**: maximum value, n: number of months with Secchi readings per year, b: number of times Secchi disk was observed touching the bottom of the lake per year

**Chl** = Chlorophyll-a ( $\mu$ g/L) – **Min**: minimum value, **Avg**: average value, **Max**: maximum value
Year	Color	Alk	Cond	pH	TP-EC	TP-SG	TP-BG	SDT-Min	SDT-Avg	SDT-Max	SDT-n	SDT-b	Chl-Min	Chl-Avg	Chl-Max
1976					10.9		7	4.2	5.0	6.5	11	1	1.8	3.0	3.8
1977													3.3	7.6	12.8
1978								4.7	5.4	5.8	3	0
1979								4.3	5.5	5.9	4	0
1980		13	44	6.8				4.7	5.4	5.9	9	1	2.3	2.3	2.3
1981								4.7	5.2	5.8	7	1
1982								4.6	5.3	5.8	7	3
1983		12		7.1	7.0			6.0	6.0	6.0	1	0	1.5	1.5	1.5
1990		14	42	7.4	7.0			4.9	5.6	6.1	12	3	2.7	2.7	2.7
1991								5.3	5.8	6.2	12	5
1992								5.5	5.9	6.2	10	3
1993								5.2	5.8	6.0	11	5
1994								4.9	5.7	6.0	12	1
1995		13			10.5			5.8	6.0	6.1	15	6
1996		12			12.0			4.3	5.0	5.6	14	0	2.7	4.7	6.6
1997								5.5	5.9	6.3	23	8
1998								5.4	5.6	5.9	11	0
1999								5.7	5.9	6.2	12	8
2000								5.1	5.9	6.3	12	6
2001		14	55	7.4	6.0	6		5.6	5.9	6.1	13	9	2.6	2.6	2.6
2002	19	16	62		7.0			5.3	5.9	6.3	14	7	2.9	3.0	3.0
2003								6.2	6.2	6.2	1	1
2004								5.2	5.9	6.3	16	1
2005								4.7	5.4	6.0	13	1
2006								4.8	5.7	6.3	12	4
2007								4.8	5.7	6.3	18	6
2008	16	12	53			6		5.2	5.6	6.1	12	1
2009								5.0	5.6	6.0	11	0
2010								5.1	5.9	6.3	13	6
2011								4.8	5.7	6.2	12	3
2012								4.6	5.6	6.0	9	0
2013								4.6	5.2	6.0	12	0
2014	17	14	53	7.5	7.0			4.7	5.1	6.1	9	0	2.4	2.4	2.4
2015								4.5	5.7	6.3	12	9
2016					8.0			5.1	5.6	6.3	20	2	3.0	3.1	3.3
2017	10	16	61	7.5	19.0		13	4.7	5.5	6.3	26	0	2.8	3.9	5.5
2018	11		64	7.2	9.8	8		4.5	5.8	6.4	21	2	2.0	3.3	5.0
2019					9.0		11	4.3	5.6	6.3	28	2	2.0	3.0	4.0
2020					8.0	8		5.5	6.1	6.5	32	15
2021					9.8			4.4	5.8	6.5	34	17	3.0	3.6	5.0
2022	9	16	76	6.6	8.2			4.9	6.0	6.4	25	7	3.0	3.5	4.0

Water Quality Trends

Long-term Secchi Disk Transparency (SDT), total phosphorus (TP), and Chlorophyll-a data are used to determine if the trophic state of a lake may be changing. Long-term trends may be calculated if there are at least 10 years of data collected within the last 30 years (1993-2022). If there are at least eight years of data within the most recent 10 years, a recent trend test may be calculated as well. The results of trend tests are presented here if there have been enough data collected from Pocasset Lake for any of these three parameters.

The Maine Department of Environmental Protection uses Mann-Kendall Tau (τ) trend tests on these data to test for significantly changing conditions. The tau value is a measure of trend direction and magnitude. Positive tau values indicate positive (upward) trends, negative tau values indicate negative (downward) trends. Values further from zero (closer to -1 or 1) indicate a stronger trend. Tau values less than -0.5 or more than 0.5 here suggest the trophic state of a lake may be changing. Trends with p-values less than 0.05 indicate statistically significant trends.

Click here to learn more about how the Maine Department of Environmental Protection uses trend test results to evaluate lakes as part of the Maine water quality standard review process.

Maine IF&W Fish Survey Data

Fish data courtesy of the Maine Department of Inland Fisheries & Wildlife.

See more about Maine’s fisheries here: https://www.maine.gov/ifw/fish-wildlife/fisheries/index.html

Fish species observed from Pocasset Lake:

American Eel	Anguilla rostrata	Native
Brown Bullhead	Ameiurus nebulosus	Native
Chain Pickerel	Esox niger	Native
Fallfish	Semotilus corporalis	Native
Golden Shiner	Notemigonus crysoleucas	Native
Largemouth Bass	Micropterus salmoides	Introduced
Pumpkinseed Sunfish	Lepomis gibbosus	Native
Rainbow Smelt	Osmerus mordax	Native
Smallmouth Bass	Micropterus dolomieu	Introduced
White Perch	Morone americana	Native
White Sucker	Catostomus commersoni	Native
Yellow Perch	Perca flavescens	Native

All fish images from Maine Department of Inland Fisheries & Wildlife unless noted below