photography and bathymetric surveys show it as approximately 2,000 ft wide. If Pass 

 Cavallo were to close, the discharge through the MSC would increase, and the channel 

 would further scour until the equiUbrium cross-sectional area was reached. 



The MSC was authorized by Congress in 1958 for a channel 36 ft deep (mlt) (38 ft 

 deep on the outer bar) and 300 ft wide. WES conducted a study in a fixed-bed movable 

 model under the sponsorship of the Galveston District to determine the hydrodynamic 

 properties and consequences of alternative locations for the cut in Matagorda Peninsula. 

 In support of the Federal study, measurements of the water level and current in the bay 

 were made in the late 1950s by the main local interest, the Aluminum Company of 

 America (ALCOA). ALCOA is stiU a major user of the MSC, which approaches its plant 

 at Point Comfort, as well as Port Lavaca, in Lavaca Bay. The physical model study is 

 documented in a comprehensive report prepared by Simmons and Rhodes (1966), and 

 additional aspects of the project are described by Galveston District persoimel (Rhodes 

 and Boland 1962; Weiser and Armstrong 1962). 



Figure 7. Matagorda Ship Channel, January 1995 



Inlet dredging through Matagorda Peninsula and the associated jetty construction was 

 initiated in 1962, with the land cut opened in September 1963. The deep-draft MSC was 

 placed 18,000 ft northeast of Delcros Point at Pass Cavallo. As predicted in the physical 

 model, the current was strong and within a few months after opening, the entrance 

 channel had scoured below the design depth. The entrance was revetted in a bottleneck 

 shape (Figure 7) and is 800 ft wide in the neck and 2,000 ft wide at the gulfward jetty 

 section. Presently, depth in the channel entrance runs from more than 100 ft just north of 

 the neck, decreasing to between 50 and 60 ft for more than a mile gulfward of the 



Chapter 1 Background and Problem Statement 



