Data period: through 2018

Town County Delorme Map # True Basin Flushing Rate Elevation
ROCKPORT KNOX 14 1 0.77 flushes/yr 123 ft
Maximum Depth Average Depth Surface Area Lake Volume Drainage Area
10 m
(33 ft) 		6 m
(20 ft) 		137 ha
(338 ac) 		8,451,992 m3
(6,852 ac-ft) 		7 km2
(2.6 mi2)

Secchi Disk Transparency Graphs

Graph Legend: Secchi symbols = average Secchi Disk Transparency Values; tick marks = maximum and minimum values for each year.

Water Chemistry and Trophic State Parameters

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 SpCon pH TP-EC TP-SG TP-BG TP-PG SDT-Min SDT-Avg SDT-Max SDT-n SDT-b Chl-Min Chl-Avg Chl-Max
1974 4.3 4.6 4.9 2
1978 14 66 1.8 3.8 5.5 3
1981 14 69 2.4 4.6 7.0 3 2.2 8.8 15.5
1982 13 69 25 0.9 2.7 5.1 8
1983 14 60 17.0 55 23 1.4 2.8 6.4 8 30.3 30.3 30.3
1984 13 23.0 22 1.4 3.0 5.0 6 23.1 23.1 23.1
1985 13 68 21 0.9 4.3 9.5 9
1986 13 68 21 2.6 3.4 4.5 6 5.4 8.1 12.4
1987 16 68 19 1.2 3.3 5.0 9 4.6 9.9 24.7
1988 13 77 17 1.2 3.0 5.5 9 4.0 9.8 19.0
1989 12 96 21 20 1.2 2.7 4.3 7 3.2 35.1 143.2
1990 13 112 6.5 29 1.7 2.9 3.7 5
1991 78 7.4 22.3 23 1.0 2.2 4.9 6 4.6 17.9 46.1
1992 11 7.0 9.6 9 3.9 6.3 9.4 6 0.7 2.8 5.5
1993 12.1 11 3.5 4.5 6.0 5 1.8 5.8 7.9
1994 13 12.0 14 2.3 3.5 4.6 5 4.5 6.5 9.3
1995 12 10.8 14 3.5 5.9 9.0 5
1996 14 44 13.2 20 3.7 4.3 5.6 4 3.0 5.2 6.8
1997 14 87 12.5 21 3.2 4.4 6.1 4 3.0 6.9 10.3
1998 12.0 17 4.3 5.4 6.1 2 3.0 3.4 3.9
1999 13 50 14.0 14 11 2.3 4.4 6.5 4 2.6 4.7 7.2
2000 16 95 14.2 18 2.4 4.0 5.0 4 3.2 5.0 8.3
2001 10 144 7.5 17.0 14 5.2 5.5 5.8 3 3.4 3.5 3.8
2002 15 16 117 13.0 14 4.7 4.9 5.4 3 3.3 7.8 14.0
2003 14 17 120 11.0 45 5.5 5.5 5.5 1 2.4 2.5 2.6
2005 6 14 127 7.4 8.0 16 5.4 5.4 5.4 1 3.9 3.9 3.9
2006 10 16 112 17.5 14 4.0 4.4 4.8 2 6.2 12.1 18.0
2008 3.3 3.3 3.3 1
2010 24.0 36 2.2 2.3 2.4 1 16.0 16.0 16.0
2011 13.0 57 3.2 3.2 3.2 1 14.0 14.0 14.0
2015 5 18 110 7.6 11.0 22 4.4 5.2 5.9 2 3.7 4.1 4.5
2018 11 2.4 3.7 4.5 5

Lake Chemistry and Trophic Summary Data - Overall Summary Values:

Avg Color Avg Alk Avg SpCon pH Avg TP-EC Avg TP-SG Avg TP-BG Avg TP-PG SDT-Min SDT-Avg SDT-Max SDT-n Chl-Min Chl-Avg Chl-Max
10 16 88 7 14 19 25 18 0.9 4 9.5 4.4 0.7 10 143

Temperature and Dissolved Oxygen Profiles

Late summer only; limited to eight most recent profiles

Units: Temperature (TEMP) = °C; Dissolved Oxygen (DO) = mg/L
2000-09-08
2001-08-13
2002-08-12
2003-08-21
2005-08-29
2010-08-12
2011-08-11
2015-09-02
Depth (m) TEMP DO TEMP DO TEMP DO TEMP DO TEMP DO TEMP DO TEMP DO TEMP DO
0 20 9.2 24 8.5 24 8.3 25 7.9 23 8.1 24 8.3 23 8.1 25 8.6
1 20 9.2 24 8.5 23 8.2 25 7.9 23 8.1 24 8.2 23 8.1 24 8.7
2 20 9.2 24 8.4 23 8.3 25 7.8 23 8.0 24 8.2 23 8.1 24 8.7
3 20 8.9 24 8.5 23 8.2 24 7.7 23 8.1 24 8.0 23 8.1 24 8.6
4 20 8.9 24 8.5 23 8.0 24 7.2 23 8.1 24 5.8 23 8.2 24 8.5
5 19 8.8 24 8.4 23 7.8 24 6.7 22 8.0 23 3.9 23 8.1 24 8.0
6 19 8.5 23 6.8 22 7.2 22 3.4 21 6.1 21 0.3 22 6.1 23 7.3
7 19 8.0 20 2.2 21 3.3 21 0.6 19 1.9 18 0.2 18 0.6 21 0.6
8 19 7.9 16 0.2 18 0.2 16 0.3 13 0.6 15 0.2 15 0.4 18 0.3
9 19 5.6 18 0.2 16 0.1 14 0.3 12 0.5 15 0.1 14 0.4 16 0.3
10 19 5.6 15 0.2

Most recent temperature and dissolved oxygen profile plots

Temperature (°C), Dissolved Oxygen (mg/L)