212 DOCUMENTARY HISTORY OF THE FLORIDA CANAL

 (The letter referred to is here printed in full as follows:)
 UNrirn STAmS DwPAxNM T or TH INTZq a,
 Washington, August 26, 1935.
Hon. J. HArDIN PMnaoN,
 Houe of Representatives.
 Mr DruA Ma. Pmuasow: Secretary Ickes has referred to me for reply your
letter of August 22 in which you request, at as early a date as is practicable, a
report on the views of the Geological Survey upon the possible effect on the
water supplies of Florida of a canal connecting the Atlantic and the Gulf across
the northern part of the peninsula.
 The Geological Survey reports as follows upon the effects to be expected if a
sea-level canal Is excavated along what is known as route 13-B, crossing the
State from the mouth of the Withlacoochee River on the Gulf of Mexico through
Marion County, thence along the St. John River to the Atlantic at Mayport:
 The proposed canal, for 40 miles or more, would be in effect a huge drainage
ditch cut deeply into the Ocala limesetone. This formation is in large part a
soft chalky limestone containing many solution cavities and channels through
which water circulates freely. It is one of the principal sources of water supply
In Florida. Its surface is pitted with sink holes; the rain sinks into it and Joins
the underground circulation. Large springs rise from it, and numerous wells
derive their supplies from it. Within a few miles of the proposed route of the
canal is Silver Spring, discharging about 500,000,000 gallons a day, appproxi-
mately the amount of water used by New York City. Silver Spring is the largest
spring in Florida. It issues from the Ocala limestone about 40 feet above sea
level. Blue Spring, almost as large, is not far away.
 A canal excavated 80 feet below sea level would cut into this porous water-
bearing limestone to a depth of about 70 feet below the present outlet of these
springs. Unless the canal could be effectively sealed throughout many miles of
its course, a procedure presenting difficulties that appear to be practically insur-
mountable, it would inevitably drain enormous quantities of water from the lime-
stone, would lower the water level in it, and might even divert the water that
now rises in many of the springs. The water that would thus be drained off now
circulates underground to considerable distances and is the source of important
municipal and domestic supplies.
 Moreover, after an unlined sea-level canal, with the passage of time, had
drained down the fresh water now in the limestone, ocean water, particularly
from the western end, would tend to enter the canal at high tide and to seep into
the limestone along the canal banks and thus to contaminate its fresh waters.
Furthermore, with the loss of head of fresh water, due to the drainage from the
upper part of the limestone along the zone of the canal, the salt water that is
already present in the lower part of the limestone would have a tendency to rise
and enter the wells.
 To summarize, there appears to be no reasonable doubt that serious adverse
effects will be produced upon the important underground water supplies of the
Ocala limestone in a wide zone extending outward from the canal line by the
construction of a sea-level canal along route 13-B.
 The particular dangers herein discussed apply to a sea-level canal only and
not to a look canal so constructed as to avoid deep cuts into the Ocala lime-
stone and thus to leave, undisturbed, the present water level in this important
water-bearing formation.
 Sincerely yours,
 HARBL SLATWrIY,
 Personal Assistant to the Becretart.
 Senator FLETCHE. Now, Mr. Chairman, in that connection I
 would like to ask the Secretary if it is not true that this board of
 review had before it reports of the Army engineers, reports of the
 P. W. A. engineers and Geological Survey, and all its data; this
 board of review had all of the material before them before they
 made their report to the President.
 Secretary ICes. That I do not know, Senator. I know it would
 have been available to them if they had wanted it, but what they
 had before them I do not know.
 Senator VANDENBERG. May I ask, if you please: Do you know,
 Mr. Secretary, whether or not it is a fact that the Board of Engineers