Thermal Profile Conducted June 18, 2005 at Lake Hopatcong
This profile was conducted by Tim Clancy with assistance by
Don Eckelhoffer. Samples were taken at deep-water areas (30+) to
determine impact of recent heat wave on suitable trout habitat.
Samples wee taken using an Aquacal deep-water submersible
temperature gauge manufactured by Catalina Technologies. Unit
was attached to a down rigger with 4 lb. weight and all samples were
taken from an anchored position to assure accuracy of depths and
temperatures (temps). Sample were collected at two foot increments
from surface to bottom and any change in temps of five degrees or
more were rechecked in one foot increments. After 30 feet samples
were taken in five foot increments because little variations were noted
at those depths. Any fractions of degrees of 3/10 or less were
rounded down and 4/10 or more rounded up to the next full degree.
Sampling Stations:
A—Northwest portion of main lake., between Cow Tongue Pt. and
Bonaparte Point at confluence of Henderson and Byram Bays.
Maximum depth 32”.
B—Northeast portion of main lake at Nolan’s Pointe. Maximum
depth 52’ but unit wire could only reach depth of 45’.
C—Center of main lake between Chestnut and Elba Points.
Maximum depth 48’.
D—Southwest portion of main lake, between Sharps Rock and Yacht
Club on Bertrand Island. Maximum depth 35’.
E—This station was added because of anomaly witnessed to confirm
results from Station A. Located further into Byram Bay between
Sunrise and Pine Tree Points. Maximum depth 30’.
Results:
Depth:
A:
B:
C:
D:
E:
0
76
76
76
76
77
2
76
76
76
76
77
4
76
76
76
76
77
6
76
76
76
76
76
8
76
76
76
76
75
10
75
75
76
76
73
12
66 *
75
75
76
67 *
14
64
74
75
76
65
16
63
65 *
74
75
64
18
60
61
69 *
71
60
20
58
59
61
63 *
59
22
56
58
59
60
59
24
56
57
58
59
58
26
55
56
57
57
57
28
55
56
56
57
56
30
54
56
56
57
55
35
N/A
54
55
55
N/A
40
N/A
53
53
N/A
N/A
45
N/A
51
51
N/A
N/A
 Denotes major temperature change and additional sample taken I’
above, depth and temp noted below.
11’-73
15’-69
17’-70
18’-69
11’71
Conclusions:
Originally it was assumed the deeper waters would have the
shallowest colder temps but this was not seen and when we sampled
closer to the outflow at the State Park the cooler temps were found
deeper regardless of depth of water. We added an additional
sampling station further northwest of station A and found conditions
similar to Station A. It was then determined that the northwest portion
of the lake remained cooler even though shallower because other
areas were impacted by the natural flow of the lake. Much of this flow
originates in very shallow and warmer areas such as Woodport,
Raccoon Is. to Prospect Point to Castle Rock Park and the River
Styx/Crescent Cove area. As these warm flows enter the main lake
they have a cumulative effect that is maximized as they approach the
downstream out flow at the State Park.
We do not know if these conditions will even out as the lake
continues to warm up but at the time of this sampling ideal trout
habitat was witnessed between 12-18 feet northwest of Raccoon Is.
and 18-22 feet downstream of there. As the summer progresses and
anoxic conditions present themselves in the Hypolinium more suitable
trout habitat may be seen in the northwest section of the main lake
than other areas.