Data period: through 2017

Town County Delorme Map # True Basin Flushing Rate
PORTAGE LAKE AROOSTOOK 63 1 11.16 flushes/yr
Maximum Depth Average Depth Surface Area Lake Volume Drainage Area
8 m
(25 ft)
2 m
(8 ft)
1,000 ha
(2,470 ac)
23,400,000 m3
(18,971 ac-ft)
176 km2
(68 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 22.0 112 13 2.7 3.0 3.4 6 1.7 2.4 2.9
1975 24.5 38 10 2.1 3.4 4.7 7 1.9 2.9 7.1
1976 12 2.5 3.0 3.7 6 0.8 2.8 6.5
1977 7 3.2 3.2 3.2 1
1981 28.0 75 19 1.9 2.9 3.4 6 4.0 4.0 4.0
1982 2.6 3.1 3.4 4
1986 17.0 52 13 3.3 3.3 3.3 1
1989 3.6 3.6 3.6 1
1994 2.8 3.0 3.3 3
1995 2.5 3.2 3.5 6
1996 1.7 2.9 3.9 5
1997 19.0 48 7.4 19 16 2.1 3.3 4.2 7 3.2 3.3 3.4
1998 1.8 5 32 2.8 3.4 4.0 6
1999 22.5 59 10 2.7 3.4 4.9 7 5.1 5.1 5.1
2000 2.6 3.4 4.0 8
2001 3.0 3.5 4.9 7
2002 31 25.0 57 9 3.0 3.6 4.6 5 4.5 4.5 4.5
2003 2.4 3.4 4.0 7
2004 2.9 3.3 3.7 7
2005 2.6 3.4 4.2 6
2006 2.8 3.4 4.0 7
2007 21 23.0 55 7.7 10 2.8 3.5 4.4 8
2008 2.4 3.1 3.5 8
2009 3.0 3.4 3.8 8
2010 2.6 3.4 3.9 7
2014 4.2 4.6 5.0 2
2015 3.1 3.2 3.3 2
2016 30 27.0 58 7.6 12 3.0 3.3 3.5 2 2.8 2.8 2.8
2017 3.3 3.4 3.4 1

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
27 21 56 7.5 16 11 11 1.7 3.3 5 5.2 0.8 3.5 7.1

Most recent late summer temperature and dissolved oxygen profiles

Units: Temperature (TEMP) = °C; Dissolved Oxygen (DO) = mg/L
1974-09-09
1981-08-19
1986-08-26
1997-08-12
1999-08-16
2002-08-20
2016-08-22
Depth (m) TEMP DO TEMP DO TEMP DO TEMP DO TEMP DO TEMP DO TEMP DO
0 18 8.6 19 9.0 18 8.8 21 8.0 21 8.2 24 7.5 21 8.6
1 18 8.8 18 8.6 21 7.9 21 8.2 24 8.2 21 8.6
2 17 8.7 18 8.8 17 8.6 21 7.8 21 8.1 24 8.0 21 8.6
3 17 8.7 17 8.5 16 8.7 21 7.7 21 8.0 24 8.0 21 8.5
4 17 8.2 16 8.7 21 7.6 21 8.0 23 7.2 21 8.5
5 17 8.0 16 8.1 16 8.4 21 7.6 20 7.9 21 5.1 21 8.5
6 17 7.9 16 8.0 16 8.3 20 6.0 20 7.6 21 4.8 21 8.5
7 16 7.9 16 8.2 21 8.0
8 16 7.9 21 7.8

Recent temperature and dissolved oxygen profile plots

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