The Portland daily press., 1874-07-01
The Canal Dam and Sebago Water.

10 he EdatOr OF the PTeSS:
Since the great freshet of 1S47 the dam at
the head of the c. & o. canal has been a
source of anxiety to the dwellers and real es-
tate owners Of the Presumpscot valley. The
Goshen reservoir disaster caused fresh alarm
and newspaper discussion; your own words
of warning induced me to visit the locality,
when is five niles northeast of the railroad
station at Sebago; the river is the line be-
tween Standish and Gorham on one bank,
and Windham on the other, from the lake to
Westbrook line.
Previous to the building of the canal there
was for three-quarters of mile below the
outlet of the lake shallow pond, called the
''basin." at the lower end of this basin
commenced the Presumpscot river proper,
which discharged the drainage of large tract
of country into Casco bay at Martins point.
The canal (for which the first charter was OBJ
tanned in 1861 was completed in 1880. This
also commences at the foot of the basin, and
before it could be filled with water, or the
line Of rivers and ponds above the lake made
navigable, dam must be constructed at the
at the lake four feet. This dam was then
as now work of much importance, holding
back as it does the surplus water, and which
was to be the protection of the whole valley
to the sea. When the dam was completed it
was considered permanent work. Except
the center section it was built of large split
granite blocks laid in courses. Against the
water side of this wall it was filed to the top
with sloping bank of very firm coarse grav
ell from high bank of that material within a
few rods. The center section of the dam, of
perhaps one hundred feet, is of timber, and
built in the most approved manner. In this
section was sluice and "waste gate" About
twenty years ago this wooden section was
considered unsafe, and the miii owners on
the river below put in another wooden dam
Immediately behind the OLD ONO to strength
en- it; through both of these wooden dams
four sluice ways were constructed with waste
gates eight feet wide, which when hoisted in
a freshet, left in the bed of the river an
unobstructed space of thirty-two feet. With
the whole lake pushing behind, it will be seen
that these sluiceo discharge an immense vol
ume of water, which greatly relieves the dam
and prevents the rise rapid of the water.
The cut stone ''guard lock'' was (very i'm
property built about 100 feet below the dam.
To connect the lock with the dam, an EN-
bankment, at right angles with that structure
was built of gravel from the hill above. This
embankment is considered the weak point.
1t is kept in place by its own weight and
sloping wall of cobble stones on both sides;
neither embankinent nor wall would
stand without the other Leaks through this
embankment are, as at Williamsburg, the
great danger. There are now two small leaks,
both of which are of long standing and in
crease slowly as the pressure increases and
then subside, which show the good quality
of the filling. The cause of the washout at
the end of the Kennebec dam was the loose
nature of the river bank. There seems to be
no way of stopping these leaks as they are at
the bottom, except to fill the canal above the
lock, or continue the dam across the entrance
to the canal. There seems to be no objection
to either of these works, if an arrangement
could be effected with the owners of the ca
nal, which is now unused andlpracticaly deal.
With this short dam built, the whole struct-
ure would seem to be safe beyond doubt, as
it has already stood forty-four years, with the
water in 1S47 thee feet higher than now;
since when it has been strengthened. Wood
does not decay when continually under wa
ter. Another assurance of the safety OF the
dam is the very slow rising of the lake, allow
ing time to repair, and the presence OF Mr..
Lindsay, the owner of the mills, whose dwell
ling is within few rods.
consider the probable effect below. 1t should
be recollected that the head OF water kept
back at this point is only five feet. while at
the Goshen reservoir 1t was thirty feet. 1t is
the height and not the extent of surface that