154 DOCUMENTARY HISTORY OF THE FLORIDA CANAL

 DOCUMENT NO. 8 (FILES OF THE DEPARTMENT OF INTERIOR),
 AUGUST 26, 19M
 COMMuNICATON FBox HamaT SL&TrrTz PlasoNAL ASSISTANT Yo THr
 SBcmrAr OFc TH IWNTrBz R, TO faSnTATIV J. HARDIN


 Under date of August 26, 1935, Harry Slattery, personal assistant
 to the Secretary of the Interior, addressed the following communi-
 cation to Representative J. Hardin Peterson. Reference should be
 made to the letter of Senator Fletcher to the Secretary of the Interior
 under date of February 13, 1936 (see Doc. 111), and to the reply of
 the Secretary to Senator Fletcher under date of February 18, 1936
 (see Doc. 112):
 AowUST 26, 1985.
 Hon. J. B An Prrnaosn,
 Bose of Representatives.
 MT Drua Ms. Pmzsou: 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 18-B, crossing the
 State from the mouth of the Withlacoochee River on the Gulf of Mexico through
 Marion County, thence along the 8t. Johns River to the Atlantic at Mayport:
 "The proposed canal, for 40 miles or more, would be in effect a huge drainage
ditch eat deeply into the Ocala limestone. This formation is in large part a
soft chalky limetone containing many solution cavities and channels through
which water circulates freely. It is one of the principal sources of water sup-
ply 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,
alproximately 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 30 feet below ea level would cut into this porous water-
bearing limetone 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 diffcultles that appear to be practically in-
surmountable, it would inveitably drain enromous quantities of water from the
limestone, would lower the water level in it, and might even divert the water
that now riss 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 lock 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,
 HBAEn SLATThY,
 Personal Assistant to the Seoretary.