Sacramento daily record-union. [volume] (Sacramento [Calif.]) 1875-1891, 1880-11-20
THE PLANS.
DETAIL OF THE PLANS FOR IMPROVING
THE sAcR AMENTo RIVER.
The Memorandum of State Engineer Hall
Referred to in the Report of Capt.
Eads Consulting Engineer.

The improvement of the Sacramento river
as food-carrying aud navigable channel is
to be effected mainly through the agency OF
the moving power of its currents, guided and
controlled by engineering works to be desig,
mated and executed for this purpose.
These works will have for their ultimate
objects-frst, the production of a channel OF
good regimen-uniform capacity to transport
the waters presented second, the mainten-
ance of well-formed, self-sustaining low
water channel; and third, the production OF
q high-water channel of sufficient capacity to
accommodate and transmit the waters of all
ordinary floods.
Although material may be taken to advan-
tage from the bed of the river for the pur-
pose of constructing levees upon its banks,
thereby enlarging its channel. yet the great
work of removing its shoals, adjusting its
widths and depths, and generally clearing its
waterway, must be performed by the moving
waters, for to talk of accomplishing this end
by direct mechanical means artificially APP
piled is to contemplate the expenditure OF
money beyond all hope of reasonable return.
Hence we are to consider the character and
moving power of the river currents.
The Sacramento river may be contem-
power and action Of its currents to produce
and maintain the channel desired. These
are, the tidal compartment, wherein the in.
fiuence of tidal action predominates over
that of the flow from land drainage in the
aggregate and throughout the year, and regu-
lates the dimensions of the channel the
land drainage compartment, wherein the
channel is formed and alone maintained by
the waters of land drainage, and the infiu-
ence of tides is not felt; and the interme-
date compartment, wherein the balance be.
tween the waters brought down from above
and those periodically sent up by the tides,
ia most variable, and the channel is
made and maintained in part by each in
ffuence-the one predominating at the time
of foods and the other at times of low water.
The lower or tidal compartment of the
Sacramento river may be with greater ap-
parent propriety taken as extending up to
the mouth of Cache slough, on the Steamboat
slough channel, ana to somewhat greater
distance above the foot of Grand Island on
the old river channel; but for convenience of
reference and to conform to the divisions of
the river mentioned preliminarily in the re-
port of the State Engineer made to the
Legislature in January, 1880, propose to
regard only the channel below the foot of
Grand Island to.the bay as constituting this
tidal compartment, this including within it
the eighth and ninth divisions of the river
preliminarily set out, as above mentioned.
The influence of the tides used to be felt at
low.water stages of the stream as far up as
the mouth of Feather river, but since the
rising of the bed, occasioned by the flow of
sands in the past few years, the tidal inf1u-
ence is not perceptible above the mouth of
the American river, where formerly there
0ft al A II
treatment of this river for the Improvement
of its channels would result in the lowering
of the water plane and the restoration of
tidal action as far up as of old. So that III
timately the intermediate compartment
would extend to the mouth of Feather river
but for the purposes of preliminary
work the limit of present tidal in
huence at low water is taken as
the upper line of this compartment, so that
it is considered as extending from the foot OF
Grand Island to the mouth of American
river, including the sixth and seventh di-
visions Of the river, as set out in the report
heretofore referred to.
Above the mouth of the American river the
channels of the Sacramento and Feather
rivers are now maintained by the action of
water moving forward to the bay contin-
uously-the waters of land drainage the &C.
vative influence cannot be counted upon to
any great extent for restoring the channel
to its former depth and improving upon its
condition generally. Here, then, is the upper
or land drainage compartment of the river.
IMPROVED TIDAL COMPARTMENT.
In general way the influence of the tides
was discussed in the report to the Legislature,
heretofore alluded to. Part H., PIP. 1858
"a, 10 TO ha nf fha 81
compartment by the removal of channel
bars, thus facilitating the propagation of the
tidal wave. For the velocity of its trans
mission is in proportion TO the square root OF
the mean depth of the channel.
These bars exist at points where the river
is widest-too wide for the volume of water
habitually presented to it-and are to be re-
moved by bringing the banks to the distance
apart which shall be indicated by study Of
the photography of this compartment as that
which affords the average well-shaped sec
ton.
At one notable point-in the turn known
as Horse Shoe Bend"-5,000 feet above
Emmaton Landing and at several Other
points also, the channel in this compartment
is too narrow, as the result of an undue
growth of point bar, and the opposite bank
is being destroyed. This is an action Of an.
By reference to page &c of Part Ii. of the
report spoken of it will be seen under the
head of acorks advisable on the loacer river
second-that all of the foregoing lines of i'm.
provements have been officially recommended
in the following words: " Removing the
channel bars between Grand Island and Col
linsville, and widening the channel in the
Horse Shoe Bend"
It is to be remembered that in contracting
the width of the channel above low-tide low.
water mark the area of the spread of tidal
waters is restricted, and the volume of tidal
wave thereby Diminished result which will
tend, in degree at least, to counterfeit the
influence for good of adjusting the width OF
the channel. And yet to adjust those widths
only up TO the low-tide low-water mark would
admit of too free an escape for the waters
over the full width of the bars at higher
stages to insure the maintenance of the de-
sired channel through them.
Bearing these points in mind, we are tC
bring the channel to the required width uI
to an elevation which will insure the conser-
vative action necessary, and plan for the
spread of the tidal waters over as great ar
area as possible above that level. With this
view my study of the subject leads me tC
adopt about the plane of half-tide at low.
water stage for the crest elevation of all con
tracing works in the tidal compartment Of
the river.
For similar reason, if for no other, Cache
slough should he left open. 1t acts as an i'm
portant basin into which the wave of tida
water is poured and withdrawn twice daily
thus affording the volume necessary to keeI
open the channel of the river below, by it,
passing up and down again.
The chief works considered necessary il
this lower or tidal compartment of the rivel
have been indicated ON page SO of the report
heretofore alluded to, under the side heading
Proposed Channel Corrections. / here restatt
them in more comprehensive form.
THE NEwTowN sHoAL CORRECTION.
A new alignment for the south shore of tbs
river, above Wood Island, to near the foot o
Grand Island.
Designed to effect the removal of the New
town shoal and the enlargement of the RiC
Vista channel.
General plan: A permeable training wal
of brush in the form of mattress on edg,
supported by piles. near the alignment of tn,
proposed new shore, connected with the
present south shore by several cross-walls Oh
spurs of similar construction.