Data period: through 2017

Town County Delorme Map # True Basin Flushing Rate
HARTLAND SOMERSET 21 1 4.42 flushes/yr
Maximum Depth Average Depth Surface Area Lake Volume Drainage Area
15 m
(50 ft) 		4 m
(15 ft) 		1,449 ha
(3,582 ac) 		65,000,000 m3
(52,696 ac-ft) 		514 km2
(198 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
1971 4.4 4.7 5.0 4
1972 3.7 4.1 4.4 3
1976 12.0 3.1 3.1 3.1 1 3.0 3.0 3.0
1977 3.7 3.8 4.0 2
1979 10 53 9.0 12.0 3.2 3.8 4.3 4 3.5 3.5 3.5
1980 3.5 3.8 4.5 3
1983 13 11.0 24.0 5.0 5.0 5.0 1 4.2 4.5 4.8
1987 15 41 7.0 17.0 4.5 4.5 4.5 1
1989 8 1.8 1.8 1.8
1995 13 10.0 9.5 4.8 5.2 5.5 2
1996 12 42 8.0 13.0 3.6 3.6 3.6 1 5.0 5.0 5.0
1997 4.7 4.7 4.7 1
2000 13 6.9 9.5 11.5 3.4 4.7 5.8 3 5.5 6.0 6.4
2001 12 6.9 8.0 11.0 5.2 5.2 5.2 1 3.4 3.4 3.4
2002 14 6.7 7.5 11.0 4.4 4.9 5.8 5 2.3 3.0 3.8
2003 11 54 7.0 11.0 12.0 4.0 4.9 6.8 6 3.2 8.2 13.2
2004 15 6.7 9.0 13.0 4.7 5.3 5.5 4 2.9 5.3 7.7
2005 13 38 6.6 15.5 3.6 4.3 5.0 5 3.9 4.2 4.6
2006 14 7.2 11.5 3.7 4.5 5.3 7 3.4 4.2 5.0
2007 13 6.8 9.0 26.0 4.1 5.0 6.7 7 3.6 4.0 4.3
2008 14 7.0 12.5 11.0 3.8 4.3 5.1 9 5.2 7.0 8.7
2009 18 10.0 13.0 3.9 4.4 4.9 5 2.0 2.0 2.0
2010 14 8.2 13.0 4.0 5.4 6.8 8 3.0 3.4 4.2
2011 4.2 4.9 5.8 6
2012 14 8.0 12.0 3.9 4.7 5.6 6 4.4 4.4 4.4
2013 8.0 11.0 3.9 4.7 5.2 7 4.3 4.3 4.3
2014 14 44 8.0 3.8 4.3 4.8 5 3.7 3.7 3.7
2015 16 43 6.0 11.0 3.8 4.6 6.0 6 4.5 4.5 4.5
2016 20 16 52 7.3 7.0 14.0 3.6 4.7 5.9 6 1.7 1.7 1.7
2017 14 51 7.4 6.0 11.0 4.3 5.1 6.0 5 4.4 4.4 4.4

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
20 14 46 6.9 9.2 8 14 3.1 4.6 6.8 4.3 1.7 4.2 13

Most recent late summer temperature and dissolved oxygen profiles

Units: Temperature (TEMP) = °C; Dissolved Oxygen (DO) = mg/L
2010-08-19
2010-08-30
2012-08-06
2013-08-07
2014-08-11
2015-08-18
2016-08-23
2017-09-14
Depth (m) TEMP DO TEMP DO TEMP DO TEMP DO TEMP DO TEMP DO TEMP DO TEMP DO
0 24 8.4 23 8.7 26 8.1 24 8.4 25 8.4 28 8.3 23 8.2 21 8.8
1 24 8.5 23 8.6 26 8.1 23 8.5 25 8.4 26 8.5 23 8.2 21 8.8
2 23 8.5 23 8.6 26 8.1 22 8.3 24 8.4 25 8.6 23 8.1 20 8.8
3 23 8.5 22 8.4 25 8.0 22 8.2 24 8.0 24 8.8 23 8.1 20 8.5
4 23 8.3 22 8.1 24 7.5 21 7.2 23 6.5 23 8.1 23 8.1 19 8.3
5 23 7.4 22 8.1 23 5.9 21 6.9 22 4.8 23 7.3 23 8.0 19 8.2
6 22 4.7 22 8.2 17 2.2 16 2.6 20 2.3 22 5.1 23 8.0 19 7.6
7 19 1.8 21 7.9 15 2.1 15 2.7 16 2.1 19 1.6 20 3.5 18 7.1
8 17 0.6 17 0.4 13 2.2 13 2.8 14 2.4 17 1.2 16 1.8 18 5.8
9 15 0.4 15 0.4 13 2.3 12 3.4 12 3.3 15 1.4 14 2.1 16 2.6
10 14 0.4 14 0.4 13 2.4 12 3.4 12 3.3 14 1.5 14 1.8 13 0.6
11 14 0.2 14 0.3 12 2.3 11 3.3 11 3.2 13 1.0 13 1.6 12 0.5
12 13 0.1 14 0.3 12 1.9 11 3.2 11 3.2 13 0.8 13 1.5 12 0.4
13 13 0.1 13 0.3 12 1.6 11 2.9 11 3.2 13 0.7 13 0.9 11 0.3
14 13 0.1 13 0.3 12 1.4 10 2.4 11 2.9 12 0.5 12 0.8 11 0.1
15 10 2.3 11 2.8 11 0.1

Recent temperature and dissolved oxygen profile plots

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