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Mustang Island, 20 miles away. It was believed that the closing of this Pass was a necessary adjunct to the improvement of Aransas Pass. The head of Mustang Island had been wearing away and the Pass had been following it. The movement from 1868 to 1878 amounted to an average of 260 feet a year. The old charts
Fig. 1. Aransas Pass; Improvements Projected and Constructed to 1887 show that the light-house is about opposite the channel of 1853; it is now 6,000 feet north of the Pass.
The plan of Captain Howell was reviewed by a board, consisting of Colonels Tower and Newton and Lieutenant-Colonel Gillmore. The board was in favor of two jetties, carried out to the 18-foot contour to afford a 12-foot channel, with groins and a flooring of mattresses to protect Mustang Island, at a cost of $759,185. (Fig.
Shore line 1879
Colonel Newton proposed to dispense with the jetty from St. Joseph Island, retaining that from Mustang Island. He feared that the mere extension of the Pass by jetties might induce the closing of the channel, as by the consolidation of the drift sand about the jetties on both sides of the channel, the impediments to the water flowing in and out might be further increased and the closing of the Pass, if such tendency existed, accelerated. One jetty on the south side of the Pass might also suffice in connection with the north shoal to sustain the ebb currents. A wider opening would be left for the flood tide; and, finally, one jetty would be less costly than the two, and the other jetty, if from further experience it was considered necessary, could afterwards be constructed. The cost of this plan was $430,980. The single jetty idea was used by the engineers of the private company later, but as will be seen, it was placed on the opposite side of the channel. The jetties were to be constructed with a foundation of reed mats which were supposed to be teredo proof, weighted with small stone, and the upper and exposed surfaces paved with large stone or concrete blocks. Brush might be placed in the interior of the work where it was not exposed to the worm.
Work was carried on under this single jetty plan between 1880 and 1885. The jetty was constructed from Mustang Island on an east and west line to a point 2,352 feet from shore, near the wreck of the Morgan line steamer Mary, in 1876, where it curved to the north for a distance of 1,698 feet, the total length in water being 4,050 feet. It extended inward to the sand hills, a distance of 1,321 feet. (Fig. 1.) It was built to about 3 feet above mean low tide and about 12 feet above the bottom. This jetty was subsequently known as the old Government jetty, or the Mansfield Jetty, to distinguish it from jetties subsequently built in this locality, Major Mansfield being the officer in charge at the time the jetty was built. A storm in 1885 carried away the top works of the jetty and otherwise damaged it. The channel at the beginning of the work was to the east of the jetty,but it had swung to the south and crossed the outer end of the submerged jetty at a point 425 feet from its end. An examination in 1887 showed that the curved portion had disappeared and that the top of the straight portion was about 3 feet below mean low water. The money spent on this jetty amounted to $393,556.95, including $10,000 contributed by the citizens of Rockport and Corpus Christi in 1883, when it was
seen that the work would cease owing to lack of appropriations by the Government.
To protect Mustang Island from wearing away, a revetment had been constructed as follows: A breakwater had been constructed across the northwest end of the island and from this as a base seven groins had been run out. The work was composed of mattresses ballasted with very soft stone and natural concrete mixture of shell and sand. At the shore the crests of the jetty were at the water surface, and at the outer end they were from 5 to 15 feet below. In 1887, these works were about all gone. The brush had been eaten by the teredo and the revetment, built on dry land, was about 100 feet from shore and, though the rate of erosion had been held to about 70 feet per year, no further reliance could be placed on the revetment.
The curved jetty had been found open to numerous objections. Its action was uncertain and irregular. Being designed to stand in the way of water flowing at various velocities, it is difficult to determine what degree of curvature will obstruct the flow enough to excavate a channel without undermining the work. If adapted to one velocity it would not answer for another velocity. There would be excessive scouring and undermining at storms and no action at average tides. It is costly to build, difficult to maintain, and badly adapted to future extensions. An extension of 2,000 feet at Aransas Pass would bring it across the channel parallel to the shore. It can not be used with twin jetties.
A revision of the plan was made in 1887 by Major Ernst, the district officer. Comparing the various surveys, he found that the distances between the corresponding contours inside and out-ide the bar had remained about the same; and that the surface width at the gorge between St. Joseph and Mustang islands had varied from 2,810 feet in 1868 to 1,785 feet in 1887. From a comparison of the maximum depth, surface width, and area of the gorge cross section at various times, Major Ernst showed that if the width had been reduced to 2,000 feet (corresponding to a maximum depth of 30 feet) without any increase in depth, the reduction in area. would have been less than 8 per cent; that is, the velocity would have been increased at about that ratio. Hence, considering the leakage through the jetties there would be no undue contraction if they were placed 2,000 feet apart. A greater distance would fail to develop the full capacity of the entrance. The gorge being sheltered from the Gulf waves, it was not to be expected that the
full dimensions of the gorge could be carried out to deep water and maintained. If the width were preserved, the depth would be decreased. With a width between the jetties of 2,000 feet it was reasonable to expect a depth of 20 feet. The plan proposed by Major Ernst was to abandon the curved portion of the jetty already constructed and to carry it by the shortest line to the deep water; and to construct from St. Joseph Island a north jetty parallel to the existing jetty and 2,000 feet away from it. Both jetties were to be extended to the 20-foot contour; to be 12 feet wide on top at the inner end and 24 feet at the outer end; to be 5 feet above mean low water and to be entirely constructed of stone, the foundations being simply a broad base of ordinary riprap. (Fig. 1.)
The head of Mustang Island was to be revetted by covering the slope from high water to the bottom of the channel with a continuous riprap revetment, 18 inches thick; the width of the revetment to be 200 feet and the length about 2,500 feet. The cost of these two works was estimated at $1,668,500. With the funds available work was carried on between 1888 and 1889 on the revetment only, nothing being done on the jetties. The money spent on the revetment was $156,859.65. (Fig. 2.) It prevented any further erosion of Mustang Island.
IMPROVEMENT ON THE PLANS OF PRIVATE PARTIES
A board of engineer officers having been appointed in 1889 to select a deep water harbor on the northwest coast of the Gulf of Mexico, recommended Galveston, but commended Aransas Pass as worthy of great consideration. In view of the smallness of the appropriations by Congress for Aransas Pass and the belief among the citizens that any money hereafter appropriated would be for the benefit of Galveston, Congress, on May 12, 1890, granted certain rights to the Aransas Pass Harbor Co., a private concern, and the Government relinquished charge of the work. Many companies had previously been formed, under the laws of the State of Texas, to form channels within the bays and to improve the passes, etc., but no work had actually been done in this vicinity except by the Port Aransas or Port Ropes Co., in 1889 and 1890, their endeavors being to form a channel across Mustang Island 10 or 12 miles south of Aransas Pass, where the island is about 10,000 feet wide. The depth of water in the channel was to be 30 feet; what work was done lasted only a short time.
The Aransas Pass Harbor Co. was organized under the laws of the State of Texas, March 22, 1890, for the purpose of constructing necessary wharves, docks, etc. Congress, in 1890, gave this com
pany the right to build and own such constructions as would be necessary for improving Aransas Pass to give a 20-foot channel. The State of Texas granted the company the right to buy land at $2.00 per acre on Harbor Island and Mustang Island, provided the company secured 20 feet depth by 1899. The earlier plans of im