There is an island in Lake Hopatcong, NJ known as Halsey Island. The
lake is about 1000' above sea level in northwestern New Jersey. I have
a home on this island and a sandy beach area by the water's edge. In
aerial views there appear to be sandy beaches at about five points
around the island where the lake meets the shore of Halsey Island. Are
these sandy areas naturally occurring or was sand brought in and
placed at the shore line, starting 100 years ago when homes began to
be built on the island. Does
the geology of the bottom of the lake support the notion that there
are naturally occurring sandy beaches replenishing themselves.

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Request for Question Clarification by pafalafa-ga on 13 Oct 2005 17:45 PDT

ennyl-ga,

I took a look at an historic online topographic map of Lake Hopatcong
from 1881, and compared it to a current topo map.

The overall shape and contours of Halsey Island seem relatively
unchanged.  The modern map shows numerous buildings on the island,
while the older map shows only three structures on the southernmost
part of the island.

Eyeballing the old and new maps doesn't provide any definitive
information, of course.  But I don't see any indications of
significant changes.

Also, I don't think there's anything especially unusual about
naturally-occuring sandy beaches in a lake, though it would take some
additional research to confirm (or refute) this.  I'd be glad to look
into this for you as a generic question, but I'd be very surprised to
find any specific information available on beach formation in your
particular lake.

Please let me know your thoughts on this.

pafalafa-ga

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Clarification of Question by ennyl-ga on 13 Oct 2005 18:38 PDT

Hi. I need to prove that the sand in the beach area of my house was
put there by humans because the lake bottom is mud and rock, not sand.
Maybe there is a document about replenishment of sand on the shores of
the lake? Or a visual that shows the areas of sand around the island
suddenly appearing where mud once was?
Thanks.

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Request for Question Clarification by pafalafa-ga on 13 Oct 2005 19:19 PDT

ennyl-ga,

Even if sand did get hauled in 100 years ago, it's hard to imagine the
beaches staying in place without regular replenishment at least every
few years Iit only takes one or two good sized storms to wash away
much of a beach).

Good luck with your situation, but I'd be real surprised to learn that
these are man-made beaches.


paf

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Clarification of Question by ennyl-ga on 14 Oct 2005 04:23 PDT

Thank you, PAF.

You might also consider the logistics of bringing sand from somewhere
and then to the island ....  I doubt it.

This doesn't directly answer your question but the level of Lake
Hopatcong was raised 6 feet in the 1750's when a dam was built. Halsey
Island was connected to the mainland before this. In the 1830's
another dam was built and the level of the lake raised 6 more feet. (I
didn't read the entire article in the site listed below, so there
could be something additional that I missed.) These dams preceded the
current dam, so the water could be at a different level now, but is
probably still high since "At the gate control house, the visitor can
see the locks [for the Morris Canal] under water at the edge of the
Lake."

"1750's -- Lake Hopatcong was called Great Pond. Around 1750 a forge
is built by New York City businessman Garret Rapalje near the southern
end of the Lake at the point where it flows into the Musconetcong
River. Called the Brookland Forge, it was located on what is now the
Hopatcong State Park and it operated for 30 years. A dam built for the
forge raised the Lake level by 6 feet, submerging areas of shoreline
and cutting off Halsey Island and Raccoon Island from the mainland.
The Lake became known as Brookland Pond."

from:
http://www.landingnewjersey.com/history.htm

You've probably been to the Lake Hopatcong Historical Museum, but, if
you haven't, they list an exhibit, "Passage to Progress: The Morris
Canal and The Transformation of Lake Hopatcong" that might be of
interest. They also list a book, "Lake Hopatcong Then & Now," which
they describe as a "152 page hardcover color book. Utilizing photos
from the museum?s collection, it documents the changes at Lake
Hopatcong over the past 100+ years. The book showcases some of the
lake?s most significant sights of the early years of the 20th century,
and then returns the reader to those same places as they appear in
2003."

If you don't get the answer you are seeking on-line, the museum (or
its curators) may be able to help you.

http://www.hopatcong.org/museum/