g the Mobile Bay Channel.
Furthermore, the Pontchartrain route is not exposed to such strong
cross currents.

The Gulfport Channel is dredged through very soft material, a
grayish-blue mud of oozy consistency, into which the sounding pole
penetrates six feet with very little exertion. On top, a small amount
of sand is found, but practically none in the lower stratum. The
material is considerably softer than any encountered on the
Pontchartrain route, except for one small stretch. Yet the shoaling is
not great. Where the shoaling is heaviest, between the end of the pier
and Beacon 10, only about 700,000 cubic yards a mile has to be dredged
out every year to maintain the channel. From Beacon 10 out, the average
annual maintenance is less than 200,000 cubic yards a mile. Except for
the four-mile stretch west of the inner entrance to the Cat Island
Channel, the bottom, on the Pontchartrain route, is harder than that of
the Gulfport Channel. Therefore, it is reasonable to conclude that the
maintenance of the Pontchartrain Channel would not average as high as
the outer portion of the Gulfport Channel.

The Atchafalaya Bay Ship Channel, extending from the mouth of the
Atchafalaya River across the shoal waters of Atchafalaya Bay, to about
the 20-foot contour of the Gulf, a distance of fifteen miles, is
through a material of slushy mud, with occasional thin pockets of sand.
The shoaling runs from 540,000 to 1,680,000 cubic yards a mile a year.
The highest rate is obtained in shallow water. Except in the stretch
mentioned, the material on the Pontchartrain route is not as soft as on
the Atchafalaya, nor are the depths as shoal, nor is there the exposure
to cross currents.

In the Houston Ship Channel, the material is composed of soft mud with
a small amount of sand. A two-mile stretch through Red Fish Reef is
practically self-maintaining. For the remainder of the channel, during
the six years from 1915 to 1920, a total excavation of 13,574,000 cubic
yards was necessary to maintain the depth. This is equivalent to
100,000 cubic yards a mile a year.

In summary, then:

1. The Lake Pontchartrain route is practically unexposed to cross
currents, as is the case with the Mobile Bay, Gulfport, Atchafalaya,
and, to a certain extent, the outer portion of the Houston Ship
Channels.

2. The material along and on the sides of the Pontchartrain route is,
with the exception of a small stretch, more tenacious, and contains, in
general,