CIF 
mum STATES 
1 EPARTi-7:17 OF TIM MITT= 
TOLOGICAL SURVEY 
cIshington 25, 5. G. 
Additional 'Alter Peveloprent on St. Tharas, V. I. 
with on Addendum on St. Croix 
By 
C. L. YeGuinness 
rzy 1951 
A new public Irater—sunply system has been developed for Charlotte 
[zone, Et. ?horns, under the Cirection of a unit of the Federal '.corks 
Agency (later General :7,ervices 2.dninistration), now a part of the Office of 
Territories, repartment of the In 
The syster as it is to be operated 
is based on the use of existing publicly owned rainfall catchments and storage 
reservoirs in Charlotte f,Lnlie, on catchment areas and storage reservoirs at 
Dou:one 2ield and the former submarLne base, and on an infiltration callery, 
storage tank, and treatment plant at Bourne Field. 
The writer has data on only the latter project (the gallery, tanks, and 
water nlant at 3ourne Field), which was developed with the assistance of the 
Geological Survey and the consulting firm of R. L. Kenan and Pissociates, 
bntgonery, Ala. Kowever, the total storage capacity of the public system 
is f-. .)]mated conservative7.7 at about 16 million gallons, including 5 pillion 
for the estimated Ifni /71 ground storage at Bourne Field as utilized by means 
of the infiltration gallery° This is the amount which, starting with all 
storage facilities full at the end of a wet season, would be available for 
use in the following dry season. It does not, of course:represent the 
annual total, for each storage facility will receive rore than one complete 
charge of water per year. Sane of the tanks nay be filled several times 
during nn average year, and even those having the greatest storage capacity 
per square foot of catchment area will receive a total cyantity amounting to 
rare than a full charge even in the driest years. 
The maximum storafT capacity of the ground' at Bourne Field, and the 
number of tires a year that it may be possible to fill it, are not known and 
can be determined only by experience under careful and intelligent operation. 
The system as a whole:if operated properly and assuming the avoidance 
of waste and of improper use of potable water, uill provide a modest supply 
adequate to meet the ninimum needs of the present population. Ilowever, the 
anticipated growth of the tourist industry, together with the improved 
standards of living and greater industrial activity that will accompany that 
growth, will inevitably result in demands for water far beyond the capacity 
of the present system. The demand was in excess of supply during the latter 
part of the present tourist season; however, the shortage was due in part to 
the fact that the system was rot yet being utilized fully. 
It is therefore apparent that development of additional water supplies 
on St. Thomas is needed. There are several possibilities, each of which 
should. be studied carefully. These include the following: 
1. Additional storage at bourne Field.--One possibility for Leveloping 
an additional supply immediately is the construction of additional storage 
at Bourne Field. The airport catchment surface has an area of about 1 million 
square feet. rurinr, the driest year it should yield at least 2 feet of water, 
or at least 15 million gallons in all. During an average year it should yield 
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at least '3 feet of water, or at least 2:2.5 million p,allors. The grouncl­
qtorae cnraeit7 is estinated by the urithr at not less than, but perhaps 
not I ach core 1har, 5 rillien 
The storage-capacity figure recomended in the rovenber 1936 (Johnson) 
renort of be nureau of Reclamation is 10 -allons for each osuare foot of 
catchment w'nerc 
su-ply is used rainly in the dry season. On that basis 
the storage capacity at 7ourre Field should bc at least 10 nill-7 on 
The rau-water tank has o capacity of 1 million and the treate''-uater tci*, 
1 million -allons. Eol:ey(r, the full ,-;:lacity si:ould not be counted az a 
part of the total storage fifxrc because a part of -L:c tanks' capacity ilust, 
be reserved for receiving and nixing uatar fro-2 various sources in the proper 
opercttion of the systen, s.; discussed in the writer's leUcr of April 3 to 
Governor de Castro. There 'or. 
it appears that additional storage capacity 
could be usecl, and the feasibility of construci'-c it should be weighed in 
relation to other means of developing additional 1:ater. A study should be 
made by a competent consultant ;rho should have, or should be given opportunity 
:Lo obtain, an aclec.uate backgroune, of kno:/ledce of the complex water-supply 
conditions on St. Thomas. 
Tt should be pointed out that the present storage racilities at the 
airport are not underdesigne0; they uere the maximum that could be prov!.dad 
withavailable 
The gallery 7roject, In partiviler, constitutes by far 
the cheapest storage t:: at could be obtained for the snail sum expendcd. 
2, 'Tells in basin of Turpentine RImIllitu Va212y1.--As pointod out in 
the 'miter's memorandum of Alpril 26:1951, entiticd 1:!cmorandum concerning 
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yerologic stuf'ics needed in 
Vlrcin 7s]ands," there lc a nossIbility 
of eltIinin7 some 
frarl 
mils in the 'casin of Turportf.ne nun. 
Though the rrospects are not highly nronisin7, they are sulTiciently good 
o justify sys;;anatic tent drIllinr and pumping. as urns should ho 
drilled al.° Dur.pe'l at selected sites. Also, records of runoff shoule. he 
collected s7steriat1c(Illy rrd continuously to help in deterrining the 
perenri-ii riclel of the basin. The conditions for tmpourdin surface .rater 
are poor, as pointed out in 
Pirnie (1945) and Johnson (1936) rn,,orts; 
the ,roblor of siltnt:cn is Cr.° of thr roct inportant unfavorable features, 
though it is rot eiscusscd at length in the t-Jo resorts 7entioned. revolopnent 
of ground .rat-,r, if fcasible„ uould tc lou-cost substitute for surfacc-unter 
developnent. 
The hydrologic stue'ies should be made by tho Geological Survey. After 
the facts are in, corpotont consultants should consi:cr thc 11racticability of 
a e-rourC-vater emelopment. 
3. Ground :later in 1urnr L- to ,valley.--,.s pointed out as early as in 
1915 by Pro Viggo Chri:I'Lci:se::, in a Parish resort translated and incluecd as 
an exhibit in the Johnson re7ort of 1936k there is considcrCole ground water 
in uet periods in the alluviun of the co-called Sugar ?state or Long 7,aiy valley 
southeast of Charlotte Analie, Infiltration L-allerles and 
1y the 
'!:-st India Co. surnlcrent that corpanyts rairlall-catchnent area. 
water supply is dininished rreatly in dry periods, especially in lore 
Pevertheless, it is possible that a useful supply could 're developed in uet 
periods and drawer on ;roll into the dry scason to suppleront other sources. 
Careful invest:r7nUen involvirq ':est drillirr and purnirrt and other studies, 
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should be rec'e by the Geolo7icol Survey to eittlire the T)ossibilities, after 
uhich n consultant shculf.7 corTare this potential source uith others, 
curel areas.--A recernaissance ehoule be rade by the Geological 
Sc7vey to locate are[qs where construction of uells or de.c.cleirlent of springs 
nay provic1e useful lou-cest sources of crater in rural areas. 
Addeo in: St Crei.x 
Bets public water supplies for Christinnsted anr rrederiksted hare been 
developed free uells located du.ring recent studies by the Geological Survey 
in cooperation uith the Federal Worhs kency (General SC-277-1CCS Administration) 
and R. L. Kenan and Acrie.,4n4."^ 
The sunplies nt rresent arc adequate for
....•6) 
the rather snall initial derands, but their adccuacy ureer heavy draft renalrs 
to be detorrined by analysis of carefully gathered operational data, Aloe. the 
valley north of the airport has teen chitin, by the studies of Cedierstrara in 1939 
and by subsequent drilling, to have a substantial crater sunnly uhich appears to 
be only partially developed at present, and studies to determine its cafe yield 
are needed. 
St. Croix,'rich Its larger drainage areas and more extensive and productive 
water-bearing forratins„ has a larger natural Crater supply then either St, 7hemas 
co St. John. It is the uriter's oplInion that the ounni:yr -till never prove to be 
enough for large-scale irrigation or in7Tt7strial use, revortheless!the 
prospecte e2 ;T' clop 
usefrl Era-pi:103 for smaller-scale lases in addition to 
eater supply, including supplamentary irri7ation, are sch as to 17arran:: 
carefta study, The st&ics should incll,.6o detailed f;round-cmter imrestigations, 
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test drilling, and punpinr: tests to evaluate favorabln areas other thar those 
now 0,:rieloped for nnhlic no° pChrist-Td rvcdf%ri7:stc 
t711r, a4rpert 
Detbleham sugar factory. Additional stu:7­les of these areas are needed also, oZ 
course, as stated previously 
In a4Mition, systoratla -receres of surface runoff fren the largest drainage 
areas should be gathnred, in order to pornit evaluating the feasibility of 
surface-storage projects. The si/tation probe:~ should be studied carefully, 
both (1) as a liElting factor in reorvoir developrent and (2) with an eye 
toward reduction of erosion 
rrthods of watershed treatrent that uill rcsiat 
in the arcllest possible reduction in surface runoff. 
The graurC-11a.7Jcl, and. suTfce-runofP studies should be nade by the Geolog-Ical 
Survey. 'The studies related to sedinentation. and watershed treatrent should be 
made cooperatively by the Agriculture Department and the Geological Survey. 
The writer knows of no substantial new water projects Vint could or should 
be unertaken on St. CrOi:: on the basis of existin data; that is, adequate 
studies should precede any such new developrents. 
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