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to them, is comparatively unobstructed, that of Indian River Bay in particular being remarkable for its nearly uniform depth and freedom from shoals. In Indian River proper, which is the westward elongation of the bay, the navigation is well maintained nearly to Millsborough, with intervening shoals of no great extent.
It was at first inferred from the language of the act that an examination of Indian River only was intended, but a personal visit to the locality and communication with those interested in the navigation showed that the name "Indian River" is locally applied to the entire body of water between Millsborough and the sea, and that the most serious obstructions which it was sought to remove lay near the inlet at the junction of the two bays.
From such information as could be obtained and the records availaable, it appears that the entrance to Indian River is no exception to the rule that the shifting sands composing the sea-beach deprive the inlet of stability in position, and that the general resultant of the forces in operation has caused a gradual movement northward.
The opening of the "ditches" described in the report of the assistant engineer, while not primarily the cause of this movement, have probably hastened it by impairing the concentration of flow necessary to the maintenance of the channel.
At the present time the inflow from the ocean encounters a nest of islands by which the currents are divided among several channels, with great loss of depth and tidal lift.
The main discharge from Indian River traverses the “ditches," and meets that from Rehoboth Bay upon the shoal north of Burton's Islands, known as “The Bulkhead,” through which the channel depth is not over 2 feet at mean low. water, with a rise of tide of a few inches only, and that dependent upon the prevailing winds.
An examination of the chart shows that it would no longer be expedient to re-establish and maintain the channel south of Burton's Islands, and the works proposed hy the assistant engineer are calculated to fix the channel approximately in its present position, and to utilize fa- * vorably the scouring effect of the outflow from both bays. The estimates provide
First. For the dredging of a channel 80 feet wide and 4 feet deep through “The Bulkhead,” following the present line of deepest water.
Second. For a channel thence straight to the inlet, protecting this by means of a dike on its northern side through to the outer or seabeach.
Third. A )-shaped dike to bring the currents on each side of Burton's Islands into more regular contluence.
Of these - The Bulkhead" dredging and the dike through the sand bar and the beach are indispensable. The >-shaped dike at the eastern end of Burton's Islands may probably be omitted without serious disadvantage; and this remark is likewise true of the greater part of the alredging through the sand-flat between Burton's Islands and the entrance. Enough of this should be done to provide for the initial movement of the currents along the dike. The attainment of the full channel alimensions may be left to the subsequent scour of the currents.
The entire estimate is $50,000.
By the omission of the works above mentioned as those that may be alispensed with at the present time this estimate may be reduced to about $35,000 as the amount required to make a navigation of 4 feet at low-water into Indian River and Rehoboth bays.
It is proper to say that were it in contemplation to establish the inlet
in the position most favorable to its future depth and maintenance and to ease of navigation that shown in dotted lines on the chart, about 4,000 feet north of its present one, would be the most advantageous.
The cost, however, would be nearly double, owing to the largely inereased amount of dredging that would be required.
The report of the assistant engineer is accompanied by a chart, a table of physical data, and commercial statistics. Very respectfully, your obedient servant,
Bvt. Lt. Col., U.S.A. The CHIEF OF ENGINEERS U. S. A.
REPORT OF MR. EDWIN IUDLOW, ASSISTANT ENGINEER.
UNITED STATES ENGINEER OFFICE,
Philadelphia, Pa., April 29, 1852. Sir: I have the honor to submit the following report upon the examination of Indian River, Delaware.
Indian River Bay, with an average width of 14 miles, extends 6 miles from the beach in a westerly direction, and there divides into two main “prongs" or branches. The principal one, called Indian River, bears a little northerly to Millsborough, 6 miles further. The other, after extending a mile south west, divides into two branches. viz: Pepper Creek, reaching west-southwest 4+ miles to Dagsborough; and Vine's Creek, south to Frankford 4 miles.
Indian River Bay has a nearly uniform depth of from 6 to 8 feet alınost from shore to shore, and vessels drawing 4 feet can ascend the Millsborough "prong” to withia a mile of that town, and the Frankford “prong” to the various landings on Vine's and Pepper creeks 1 to 2 miles from their mouths, encountering, in either case, oniy a few mud flats of no serious importance.
White's Creek, flowing north ward from Ocean View parallel to the coast, empties into Indian River Bay at its southeastern extremity, and is navigable for vessels of 4 feet diaught to within a short distance of Ocean View, 5 miles from its junction with Indian River Bay.
In addition there are numerous smaller creeks which, althongh not navigable for any distance, are still useful in furnishing good landing-places for vessels trading to vheir vicinity.
Rehoboth Bay, adjoining Indian River Bay, to the north, is a sheet of water about 4 miles long by 2 wide, separated from the ocean by a low, narrow sand beach, and with two large creeks (Herring and Love's) flowing into it. Large sand flats stretch out from the eastern or beach side, caused by easterly storm tides sweeping across from the ocean and transporting the beach sand; but along the western shore a 6foot channel leads from the head of the bay to a shoal called “The Bulkhead," near Burtou's Islands, to be described later on.
About the year 1800, and before any charts had been made of this locality, the inlet, according to local information, was at the eastern extremity of Indian River Bay and nearly on the prolongation of its axis at a point about a mile and three-quarters south of the present entrance. At that time what is now Burton's Islands was a peninsula joined to the main land by a narrow neck of marsh, and Rehoboth Bay discharged into Indian River Bay through a channel between the eastern end of this peninsula and the beach. The owner of the peninsula, in order to keep cattle from straying. dug two ditches through the neck, which have since continued to be known as the
big” and “ little ditches." The southwest wind, which prevails for several months in the year and has a sweep of 5 miles across Indian River Bay directly into these “ditches,” caused the water to How through them into Rehoboth Bay, from which it found its way to the inlet through the channel around the eastern end of Burton's Islands.
There are no data as to the character of the iulet at this time, but tradition states that previous to the opening of the “ ditches" vessels drawing from 5 to 6 feet were able to get over the bar at the entrance and sail directly to the various landings on Indian River Bay and its tributaries without encountering any serious obstructions, Persons interested in the navigation agree in stating that from the opening of the "ditches" dates the beginning of the gradual working of the inlet to the north aud the shoaling both of the bar at the entrance and of the inside channel.
The first reliable data that we have on this subject are from the chart of the United States Coast Survey made in 1843, giving the position of the inlet 17 miles north of its position in 1800 and one-half mile south of its present one.
The main channel at that time was on the south side of Burton's Islands, and had 31 feet of water on its shoalest bar and on the bar at the entrance 11 feet.
This would enable vessels drawing 4 feet to pass into Indian River Bay, taking advantage of high-water and fair weather.
The field-work of the present survey was completed between March 8 and April 6, 1882, the weather being exceptionally boisterous and interfering greatly with progress.
In pursuance of your instructions my principal efforts were directed to the examination of the inlet and the location and cbaracter of the bars and shoals in its immediate vicinity.
For this purpose a base line of 3,4454 feet was measured on the inner beach north of the inlet, and from it the principal points and stations on the veighboring shores and islands were determined by triangulation. The topography was sketched in by the aid of the sextant and the soundings were located by simultaneous observations with two sextants.
In addition a reconnaissance was made of Indian River to Millsborough, and of Rehoboth Bay to the mouth of Love's Creek.
In the reconnaissance the Coast-Survey chart of 1843 was taken as a basis for the general topography and the soundings were located by compass-bearings to such prominent natural objects as could be recognized on the chart.
The inlet in its present position is one-half mile north of its location in 1843, and has 2 feet at mean low-water on its onter bar.
In traversing the beach the channel turns to the north and, making a deep bend, curves around again to a point opposite the entrance, where it divides into two branches. The one aronud the eastern and southern side of Burton's Islands is broad and shallow, while the other, passing to the vorth of Burtou's Islands, and between them and Cedar Island, is now the main channel. Where confined between the two islands it is from 6 to 10 feet deep, but after leaving Cedar Island it enters the broad end of Reboboth Bay, and the flood tide spreading loses its velocity and deposits the sand brought in from the ocean, forming what is known as “The Bulkhead," over which there are only about 2 feet at mean low-water.
3014 Owing to the shallowness of the channel south of Burton's Islands Indian River now discharges almost entirely through the two “ditches," which have so increased in size that the “big" or northern “ditch” is 350 feet wide and 15 feet deep, and the “little ditch” 400 feet wide and 8 feet deep.
The flow from Indian River meets the discharge from Rehoboth Bay near “The Bulk. head,” and, together, they pass through the main or Cedar Island channel.
At the northeastern end of Burton's Islands this current is met nearly at right angles by the outtlow around the southern and eastern sides, giving a detlection to the current that is the probable cause of the deep curvature into the north beach. These sinuosities have the effect of reducing the velocity and destroying the scouring force of the current.
The sea beach for a distance of 1,300 fuet north from the inlet is only a low, narrow sand-spit, bare at ordinary high-water, but submerged during an easterly storm tide. Beyond, it rises into sand-duues from 6 to 10 feet high.
The south beach rises almost immediately into sand dunes of about the same height.
Bounding the channel to the southward, and between Burton's Islands and the entrance, is a large sand flat, bare at low-water, but covered at half-tide.
For the improvement of the entrance and the maintenance of an increased depth of water on the outer bar, it is necessary to give the ebb-tide its maximum scouring force by means of a straight channel through the sand flat from the mouth of Cedar Island channel directly to the inlet.
For the preservation of this cut through the loose material of the shoal, and to control the northward movement of the inlet, a dike, marked B on the chart, will be required, baving a total length, from the southeast end of Cedar Island to the south point of the north beach, of 2,275 feet; and an extension of 200 feet thence to the 2foot curve outside would be desirable.
Another (A-shaped) dike, marked A, will be needed to bring the waters of Cedar and Burtou's Islands channels together at a more favorable angle. It will have a total length, in the two arms, of 520 feet.
At present the most serions obstruction to navigation is “The Bulkhead," since, once across it, vessels can pass througin the ditches" to any part of Indian River and te the west shore of Rehoboth Bay.
Although the inlet is anything but “good," still vessels drawing 41 feet cross the har, owing to the greater rise of the tide; but, unless they reduce their draught to less than 3 feet, they will be unable to get over “The Bulkhead.” This compels the
larger vessels to load just inside the inlet, from lighters bringing freights down to them a distance of 10 or 12 miles from the bay landings.
Tha smallest vessels trading to Indian River are now obliged to lighter over this sboal; while, if it were removed, they would be able to load at the various landings and sail directly for Philadelphia or New York.
The cost of freight is not only greatly increased by this rehandling, but also by the uncertainty as to the time; for vessels, during a range of low tides, have lain agronnd on “The Bulkheads" for as long as three weeks, and one week is about the average time consumed in getting over it. This renders' it impossible to ship any perishable freight, such as fruit, vegetables, fish, or oysters.
The proposed improvement consists in dredging a channel 80 feet wide and 4 feet deep at mean low-water along the present line of deepest water, to connect the 4-foot curves on each side of “The Bulkhead.” Thecut will be 3,000 feet long, and will require the removal of 14,800 cubic yards, at an estimated cost of 25 cents per yard.
The vessel-owners attempted, about twenty-five years ago, to improve the navigation by closing, by means of dikes, all but the principal channel, which at that time was on the south side of Burton's Islands.
This afforded a temporary relief, but a heavy storm tide, about eighteen months later, swept the dikes away.
About six years ago a narrow channel was dredged through “The Bulkhead," which has since almost entirely filled up, for the reasons that it had not sufficient dimensions to maintain itself, and that the material removod, being placed on the opeu side of the cut, was carried back by the ebb-tide from Rehoboth Bay.
The tides in Indian River and Rehoboth bays are extremely irregular and greatly affected by the wind.
The shallowness of the bar at the entrance, the numerous sand bars and shoals inside, and the sipuous course of the channel prevent the flood current from reaching more than about a mile from the inlet, and although there is a variation of level of from 6 inches to a foot as far as the heads of both bays, it bears almost no relation to the ocean tides, but is caused by the wind banking the water to leeward at one end or the other.
From the limited amount of both time and money allotted to the survey, no prolonged tidal observations could be made; but an examination of the records kept at the one tide-gauge established gives, as a mean of twenty-six observations, a rise and fall of 1.04 foet at a point about one-eighth of a mile inside the inlet.
During an easterly storm, driving the water into the inlet and across the beach itself, the high-water recorded 1.88, or 0.84 above mean high-water. But, the storm continuing, the greatest high-water was obtained two days later, when the wind, shifting to to the west, and blowing hard, returned the water previously accumulated in the upper part of the bays, and gave a high-water on the gauge of 2.28, or 1.24 above the average.
The low-waters were affected by the wind in a similar manner. The highest lowwater was obtained after a light northeast wind on a flood tide had given a highwater of 1.58 on the gauge. Shifting to the north west on the ebb tide and blowing hard, the wind drove the water down the bays faster than it could be discharged, and gave a low-water 0.88 above the average.
Westerly winds continuing for several days so reduced the level that the low-water recorded 0.62 below the mean, and the flood current was represented by only a slight swelling on the gange of from four-tenths to six-tenths of a foot.
A comparison was attempted between this gauge and the standard one on the gov. ernment pier in the Breakwater Harbor, 16 miles north of the inlet. But the local causes just mentioned so largely affected the Indian River levels that no comparisons of any value could be made.
The rise and fall on the standard gauge at the breakwater is 4.06 feet, and this is useful as giving the probable rise and fall in the ocean outside of Indian River Bar.
Were the inlet fixed in position and of favorable depth, with a straight channel and no bars, a certain proportion of this rise and fall would be imparted to the surfaces of Indian River and Rehoboth bays, and the mouths of their tributaries, a tidal area of about 20 square miles, and the scouring effect of the largely increased discharge would tend to maintain a permanently improved depth of entrance.
Indian River and Rehoboth bays and their tributaries drain an area of about 25 square miles, over which an aunual rainfall of about 38 inches may be assumed from the average given by the United States Signal Service for Philadelphia for the last six years.
Allowing 40 per cent. for absorption and evaporation, there will be an average of 32,635,000 cubic feet of fresh water draiuing into Indian River and Rehoboth bays aily. The current of these bodies of water being sluggish, the expanse considerable
and the depth comparatively small, there will be a large surface evaporation, which
The average area affected by the tide is about 20 square miles. If a mean depth of
Tabulating these results:
Total contents tidal prisin...
139, 392, 000
154, 392 000
Assuming the average velocity of the ebb-tide to be 3 miles per hour, this discharge
The channel to the inlet is estimated for a width of 150 feet and a mean depth of
hour, maintained for a variable length of time, depending on the wind.
Observations of the direction of the flood-tide were made on April 5, the weather
Total A, 520 feet, at $8 per foot..
COMMERCIAL STATISTICS INDIAN RIVER, DELAWARE.