MlkWli^^i^^Hi'i!'i;ii;^';'fi^ state of california deparhjimt of public VDRKS FRA^IK F. liffiRK[AI\!, Governor EARL LEE KELLY, Director of Public Woiks DIVISION OF WATER RESOURCES BULLETIN NO. 48-A SAN L U !_ S HEY H I. V E R " i N V E S T !_ G A T I_ N 1926 DepartiTB nt seal Sacramento , 1937 rlil *■■■■ T.\BLE OF CONTENTS Page ACKNOWLEDCSvIEMT 'v-lii' ORGMIZATION ix FOuEWCnD X CHAPTER I INTRODUCTION, SIB-MXRY AND CONCLUSIONS 1 SUJM.VRY ___ -. 2 Water supply ------------------ 2 Yieli of reservoirs -------------- 3 Storage reservoirs --------------- 4 Bonsall ian anl reserve ir ----------- 4 Costs of Bonsall reservoirs ---------- 5 Monseratc iam ani reservoir ---------- 6 ■ Flood control ----------------- 7 CONCLUSIONS 7 CH.-iPTER II HYDROGRAPHY 9 Full natural flcr? _-_ -___---- 9 Available flew ----------------- n Flocl flows -__-_--_--_ ____ 17 CH.1PTK; III CONSERV..TION :M) FLOOD CONTROL -__--. 13 Present level oprsnt -----------_-__ 13 Reservoir sites --------_--_--_- 2C Ill T.iBLE OF CONTENTS, Continued. Page Evaporation ------------------- 28 Yields 28 Flooi Centre 1 — __-_-_ __-__,__ 31 CIL'JT^ER 17 BONSALL DAM AND RESERVO r^ 33 Geology — _-_------_-_-_----- 33 Excavati on------------------- 34 Materials for construction --------- — 39 Dam ani reservoir ---------------- 3S CHx-iPTER V MONSERATE T):M AND RESERVOIR 46 Geolo^^y --------------------- 46 Excavation -------------- — --- 47 Comparison of Monserate --ni Bonsall -am sites - - 47 ;LPPS^JDIX A TOPOaRAPHY 0? BONSALL DM SITE ..ND RESERVOIR Appendix A consists of ei^t tracings t'jcnty-ei.jht inches by forty inches in size. T'.tc she -.t the topography .f the Bonsall C.aa site at a scale of one inch equals one hunlreci feet with five foot contours ani the location of the various exploratory workings. One shows profiles f the various cxpl^.r at ions and the classifications of the materials encountered. Five show the topography cf the Bonsall reservoir at a scale of one inch equals four hundred feet with a contour interval .f ten feet. IV Since these tr^cin^s were sc lar^e :^Td since their value Jepends tc a lar^e extent en the size cf the scale, they have n.:t been re-^roiucei fcr :;eneral listributicn. Black line tricinTs frcn which reprcJiucticns can be :r.ade have been filed with each f the cc operative agencies; the Works Pre :ress .lininistraticn in San Die x , the Ccunty of San Dic.gc , the City of Oceansi.e, ani the Carlsbad Mutual '..ater CcLipany. .\PPZNDIX B. TOPOaR.iPHY 0? MCNSERAT2 DAM SITE AND RESE^^VOI^^ Appendix B consists ^f four tracinjs twen ty-ei :;h t inches by forty inches in size. One shows the topo'iraphy .f the Hcnserate daa site at a scale cf one inch equals one hundred feet v.'ith five feet con- tours onl the profiles cf the explorations vrith a classification :.f the naterials encountered. Throe show the topOi^raphy of the Monseratc reser- voir at a scale cf one inch equals four hundrel feet with a contour interval cf ten feet. Since these tricin^s vverc so lar^e and since their value depends to a larje entent on the size cf the scale, they have net been reproduced for general distribution. Black lino tracings frcn V7hich reproductions can be :ade have been f ile 1 \7ith each .f the cooperative agencies; the ",.crks Prcsress Ainini strati en in San Dic^c, the County cf San Die JO , the City of Oceansile, and the Carlsbad Mutual '..ater Company. LIST OF TABLES Table Chapter II - Hydrography Page 1. Full natural flow cf San Luis Rey River, origi- r^ting between Henshaw Dani md gaging station near Bonsall — _________________ 12 2. Estimated runoff of San Luis Rey River at gaging station near Bonsall had present diversions beai made in the past. ----------------- 14 3. Probable size and frequaicy of flood flows on the San Luis Rey River at Oceanside f ran the drain- age basin belc77 Henshaw Dan --- — _-____- 17 Chapter III - Conservation and flood control 4. Areas and capacities of Bonsall reservoir — _ - - 23 5. Areas and capacities of Monserate reservoir - - - - 24 6. Con pari son of flooded areas and capacities of Bonsall and Mcnserate reservoirs --------- 25 7. Yields of Bens all reservoir — -- 28 Chapter IV - Bens all dam and reservoir 8. Logs of ;7ells drilled at Bonsall dam site ----- 35 9. Costs of Bonsall r eservoi r - 100 foot dxi — - - - 41 10, Costs cf Bonsall reservoir - l-iO foot dam- - - - - 43 Chapter V - Monserate dam 2nd reservoir 11. Logs of Trells drilled at Monserate dam site - - - - 48 vi LIST OF PUTSS Finite Page Chester II - Hydro :^raphy Drainage basin of the San Luis Rey River in Sen Die.^o County - — _________________ lo Chipter III - Ccnservaticn anJ flood control II Areas and capacities of Bccsall reservoir ------ 21 III Areas and capacities cf Mcnserate reservoir — _ - - 22 'IV Operation cf Bcnsall reservoir on San Luis Rey River ___-- _ ____.___- jc V Effect of Bonsai 1 reservoir en flood discharge - - - - 32 Chapter IV - Bonsai 1 dan and reservoir VI Bonsall dan on San Luis Rey River ---------- 41 Appendix A - TopO;p:aphy of Bonsall dansite and reservoir. 23 inch by 40 inch tracin^-s filed with sponsoring agencies I-A Topc^raphy cf Bonsall dan site - sheet 1 II-A Topography of Bonsall dan site - sheet 2 III-A Exploration of Bousall reservoir IV-A Topography of Bonsall reservoir - sheet 1 V-A Topo2ra;hy of Bonsall reservoir - sheet 2 VI-A Topography cf Bcnsall reservoir - sheet 3 VII-A Topography of Bcnsall reservoir - sh^et 4 VIII-A Topography cf Bonsall reservoir - sheet 5 Appendix B - Topography of Mcnserate dan site and reservoir. 28 inch by 4Q inch tracings filed with sponscrir^j ajer^jies I-B Topograjdiy and Exploration of Mcnserate dan site. vn LIST OF PLATES, Ccr.tiiiied Plate II-D Tcpc.£-raphy cf "IcriseratG.reser'vo ir - sheet 1 III-3 Topogrc^^hy cf Hcnserate resorvcir - sheet 2 IV-3 TopcT?a-;hy of Mens era te reservoir - sheet 3 Vlll ACKNOV.'LEDGEIvlSNT This bulletin has been ^^reparc-i by the Divisicn cf V/ater Resources of the Departnent of Public Works cf the State ct Cal.ifcrnia in cooperation r/ith the Feier-il Govcrnnent vVorks Prepress Aininistratic n, the Ccunty of San Die V , the Citj'- cf OceansL'ie, ani the C-irlsbal Mutual \latoT Ccnpany. The respective snares of each cf the cocperatin-^ a'^enciss in the financinj of this investi.'^ation were as follows: Vorks Prcc;ross A-fciinititr-.ticn $ 22, COO. 00 Division of Water Resources 2,500.0J County cf San Diejo 1,000*00 City cf OcGonside 750,00 Carlsba^ Mutual Water Coupany 750.00 $ 27,000.00 Additional viluablo ail .las fumishcl the investi 'Ration as follows: By Messors. Ernest Ronsse, B. a. S'./cet, ani R. M. ■iYidenhani, the oMnors of the Bcns.-ill isni site and by Llr. Cterles E. Cocper, the c\mer of tho Monscrate dan site. By the City of Oceansi'.c, in furnishi:i~- free cf charge, office space, li pt anl t clcphono f acilities. By the County of San Die :c, in the transpcration cf equipncnt to and frcri the ta. rk. By the Carlsbad Mutual '..'ater Cci.ipnny, the City cf San Diep anl ether divic ajoncies, public officials and private individufils, thrcu:h the loan cf equipment and the furnish in--^ data aid valuable assistance. The Division cf '..'ater Resources v/ishes tc express its appreciation of the cooperaticn furnished by all the rienbers of the icrks Pre -^ress Adnini- straticn b.th in the fiell and in its San Dic3o office. The morale .f the worker assigned to the project v/as at all tines hi'^h and their interest in the invosti :aticn and desire tc help tcv,ards a wcrth-whilc result were always apparent. ORa:VNIZ..TION STATE ? C .. L I ? R N I A IX Frmk F. Mtrri'in Earl Loe Kelly- Edward Hy-itt Governor Director of Public Works State Engineer This bulletin w";s pr^pcirod under the direction of ^. D. Edmonston, Dopuly St.itc Engineer by ROBERT L. V/INJ, .issociato Hydraulic Engin'^er ..iS;jisted by P. H, Von Etten, Senior Hyd.-aulic SngLn^er, -fiho acted in an advisory capacity in the prolimin-a'y stcges of the invectigation Chester Marliavo J. L. Jamos Engineer - Geologist Delineator J. J. HJ-ey, Jr., .administrative Assist. .nt WORKS PROGRESS ;. D :i I N I '' T R A T _I N Frank Y. l"!GLaughli.i Ralph ".Yadsvrorth George B. V.hite R, M. Gregory E. L. Fre^^land .idministrator Deputy .drainistrator DISTRICT NO. 12 Director Chief Engineer Supervisor, Division of Operations ..ssi St 'Jits J. II. Graves, Field Super intend :int Byron Johnson, Trans itrcaxi. C. Li. V.'atson, Topcgrzphcr Roland Curran, Delineator Thos . II. Hye, General Foreman. Lee ^irbuckle , Topo._^rapher Harold Clark, Topographer D -all as Kime, Delineator FOREWORD In 1935, the Division of Water Resources, Department of Public Works, State of California, published Bulletin No. 48, "San Diego County Investigation". In that Bulletin were presontcd "detailed data and infor- mation on the water supplies and agricultural lands of San Diego County; the present status of irrigation and domestic and municipal water supply developments; the utilization of water supplies from surf ice and under- ground sources; the irrigable I'Sids and uater requirements and the domes- tic and municip:;l water requirements of the metropolitan area; the flood flows of the principal streams and probable frequency of occurrence". The San Luis Rey River was included with the other San Diego County streams, in that bulletin. The data and information presented, however, was gene- ral in character and no detailed plans of development or estiimtos of cost were made. This report presents the data and infoimation obtiincd from an investigation of the San Luis ReyrRiver Basin which covered a revision of the estimates of runoff given in Bulletin No. 48; the amount of storage available in reservoir sites at Bon sail and above Monserate Narrows; the probable yields available fror. the Sixn Luis Rey River; the results of geologic investigations of the damsites including surface explorations, tunnels and T7ells; and the probable costs of developing the reservoirs. CHAPTER I INTRODUCTION, SIMVL'^Y AND CONCLUSIONS In 1933-34 the Division of Water Resources m-ide a study of the hydrology of Son Diego CoiKity. The results of this study were presented to th^ public in Bulletin No. 48, "Snn Diego County Investigation". Analyses of the probable full natural flo'.vs of the various strear.is, the probable sizes and frequencies of the floods which might be expected to occur en these streaids, the n^ed of the county for additional water sup- plies, and a plan for the full development of the San Diego River for conservation and flood control purposes ;7cre presented in that bulletin. In 1935 the City of Ocoanside, the Carlsbad Mutual Water Company, and the County of S^n Diego, realizing th:it the present draft on the San Luis Rey River, the source of water supply of the City and the Water Com- pany, was approaching the nnximum safe yield cf that stre.,m without addi- tional development, requested the State Division of Water Resources to sponsor an investigation of the San Luis Rey River by the Works Progress Administration of the Federal Goverrjcent . Accordingly, the Division filed an application for such .an investigation with the Works Progress \drair.i- stration on September 3, 1935. This application was approved by the Federal officials Decanber 3B , 1935 and woric was commenced March 11, 1936. The Division cf V/ater Resources, acting for the sponsoring agencies, agreed to fumi^ technical supervision, the well drilling rig, and office sup- plies. The V/orks Progress Administration agreed to supply all labor, both common and technical, and the materiels to bo used in the field. Hov/ever, the Works Progress Administration had difficulty in finding qualified technical workers both in the field and in the office and consequently it bec-ane necessary to modify the original plan of operation. More mcney was spent on the geological exploration of the dam sites Tid on topo- graphic surveying and less on analyses of the data obtained than v/oull have been the case had adequats technical help bo.^n available. All the analyses have been nude by the onployes of the Division of u'ater Rasoiirces» The field v/ork of this investigation included geological -xplo- rations of tTC dar. sitos on ttie San Luis Roy River; one, tTro miles V7est of Bons?J.l at the State Highway crossing , the o th^r , at the Monserate Narrows four miles r/est of Pala; and topogr:.phic surveys of both dan sites and of the corresponiing reservoir basins. The office analyses consisted of cstirr.ting the runoff avail ble for conservation, the capaciti s of the reservoirs, tiie probable yield for consumptive use, and the costs of such a vrater supply, Vrater Supply The San Luis Rey River drains a basin of some 565 square miles in extait. The Henshaw DaT. at the lower end cf the V,'arner Valley controls the floTT from the upper 206 square miles of this basin. The Escondidc Mutual Water Company diverts v;ater out of the basin.. The Rincon and Pala Indians and numerous other private cv.-nv^rs pump v;ator from the river bed for the irrigation of the overlying river bottans. Had the present upstream diversions b^en in effect during the 48-year period from 1887 to 1935, the mean seasonal flow past the Bonsall dam site would have been 23,170 acre-f ^ct. This flc:;, as shcv/n in the folloTTing table, varied frcm seascn to season, bet:7een ■:Tidc limits. S3..S0NAL RUNOFF OF S.J\f LUI? REY HWEH AT BON^.iL DM SITE WITH EXI-^TING UPSTRS.iI D VERSIONS Runorr, : Runcf x" , Runoff; : 1 Siv-ison in So '-.son : in ' Scis.i: '• in .i.cro-f cut ■ ;crc-f ^-jt .xr;-i'.;ct '• ' 1887-88 13,690 1903-04 : 2,670 : 1919-20 9,400 : • 1888-89 27,340 1904-05 : 22,390 1920-21 2,240 : • 1389-90 43,930 1905 -C 6 : 56,133 1921-22 56,530 ' • 1890-91 26,890 1905-07 : -13,330 1922-23 : 14, 580 : ' 1891-92 17,750 19C7-08 : 13, 750 1925-24 : 3,520 : • 1892-93 21,500 1908-09 : 25,750 1934-25 4, 150 ■ 1893-94 '7,410 . 1909-10 : 25,460 . 1925-2 6 : 16,060 : • 1894-95 88,260 1910-11 : IB, 020 : 1926-27 75,680 : •1895-96 5,020 . 1911-12 : 6,530 • 1927-26 7-, 100 : '• 1896-97 14,200 : 1912-13 : 3,180 : 1923-29 : 7,230 : •1897-96 2,920 : 1913-14 : 19,740 : 1929-30 10 , 930 : • 1898-99 1,350 . 1914-15 : 76,120 : 1930-31 : 4,610 : •1899-00 1,550 : 1915- 16 : 160,970 : 1931-32 47 , 100 : • 1900-01 8,520 : 191^17 : 21,940 : 1932-33 : 9,410 : '• 1901-02 5,630 • 1017-18 : 15,250 i' 1933-34 : 3,410 : •1902-03 7,450 : 1918-19 : 8,340 : 1934-3 5 10,190 : ;-i8-yo^,ir (li 387-1935) m- 'i: scso nal runci'f 23,170 In the season 1898-1899 only 1,350 acre-foot ..f water -.Tould havG passed the d:m site v/hile in the soiac n 1915-16 there vzt uld have been a flcw :f 160,970 acre-fv^et. This variation is pericdic as /ell as seasonal, as is shv.:;ri by a compari sen of the seven-ye^T means for the periods 1897- 190-x, 4,300 acre-feet and 1913-1920, 44,540 acrc-fcet, .;hich shov;s that the 77et peri^-d pr^uced cvex 10 timos aa much runoff .s thj dry period. , Yield of Roservoirs A. large amount of storage space is needed tc ccnserve surplus water fro;a wet periods for use in dry periods. Studios f the .peration of the Bon sail reservoir f c r c nservati-.n sh.ii th.t a reservoir capable of storing 49,170 acre-foot -f water in the B-nsall basin, vruuld pr.duce a net safe yield :.f 6,020 acr.,-feet; that v7ith a reserve, ir f 95,780 acre- feet capacity the liot safe yield cm be increased t^ 8,530 -crc-feet; and that 162,610 acrc-foet .f stcrf^e Trill provide a not safe yield :f 12,730 acrc-feot p^r scr.an cr, accoptiag a 25 per ccut deficiency during -cho I'tst fcur years f the cxcupticnally dry period 1895-1905, a sjas^.nal yield •;f 14,130 acrc-fcct. In additicn tc the stc rago g) aco prc\-idcd by a r^jscrvcir in the B^-nsall basin, tlxrci is also 'jvail_blc sane 12,300 acrc-fcct cf underground storage space iL. the Mission b.iSin bot'.Teen the Bonsall d'lm site aiad Oceansidc M-hich should yield an additional 2,000 acre-feet cf v/ater p>2r season. Storage Reserve irs -i reconn.aissance survey ef tho Sa.-; Luis Hey River basin from Oceanside tc Rincon was irp.dc in search', f possible reservoir an3 d :n sites. This survey indicated that the mc st favor ?,ble dxi sites "ere in the Bonsall Narrows at the State Highway crossing, storing r/ater in the Bonsall basin and r.t the Moiiserato Narr: -.vs , storirg water in the Pala Basin, Both of these sites have been expl. red :jnd the topogr.phy inippod. Bonsall Dam 2r.d Hosorv.. ir The exploration and geological investig :tion ■ f the Bonsall dam site sho -.7 that an adequate found xticn for an earth fill dani could be pre- pared with only a fov/ feet of cxci-vation en the abutnEnts and with a r.iaxi- raum excavation cf about 55 feet in the river bed. The topographic surveys v,f the reservoir site sh^u that a dain providing an 80 foot depth cf -.is.tjr wcvild st^re 49,170 acre-feet, a 100 foot depth v;^ uld store 95,780 acre-feet, -jid a 120 foct depth -.XJuld atcre 162,610 aero feet. The preliminary design of an earth fill dar^. f i r this lociti^n provided for a twenty-fcot free board bot,;een the spillvrij' lip and the crest of tho dom; an upstream sl-.po of 2,5:1; a crest width :f 50 f Jot; a down stream slcpe -f 2,5:1 fcr the top 40- feet -f height and :f 3:1 for the remaining distance; an upstream impervious section 7d.th a ton foot crest 49,170 162,610 100 140 6,020 12,730 14,180 8,020 14,730 16,180 5 width, a down stream slope of 1:1, and an upstream slope of 2.5:1 faced with a concrete paving* Excavation in the river bed extended to bedrock under the impervious section but only throu.eh about two feet of stripping under the pervious section. The capital and annual costs of such a dam for heights of 100 and 140 feet pre shown in the follov;ing table: COSTS OF 30NSALL RESERVOIRS Storage Capacity, in acre-feet Height of dam, in feet *Seasonal yield with no deficiency, in acre-feet *Seasonal yield with 25 per cent deficiency, in acre-feet *Seasonal yield including Mission Basin with no deficiency, in acre-feet *Seasonal yield including Mission Basin with 25 per cent deficiency. In acre-feet *Increase in seasonal yield including Mission Basin v;ith no deficiency over present yield of 5,900 acre-feet, in acre-feet 2,180 8,830 *Increase in seasonal yield including Mission Basin with 25 per cent deficiency over present yield of 5,900 acre-feet, in acre-feet 10,280 CAPITAL COSTS - TOTALS #3,759,000 $5,316,000 Per acre-foot of storage 76.40 32.70 Per acre-foot of seasonal yield with no deficiency 624.00 418.00 Per acre-foot of seasonal yield with 25 per cent deficiency 375.00 Per acre-foot of seasonal yield including Mission Basin with no deficiency 469.00 361.00 Per acre-foot of seasonal yield including Mission Basin with 25 per cent deficiency 329.00 •The small safe yields as oomparod rrith resorvolr capacities are caused by the extremely dry period I857-I904 in which the averaee runoff was only 4,3P0 acre-feet. They do not include any possible savings of present natural losses by transpiration from the vegeta- tion \Thich would be cleared fron the reservoir basin. for acrc-fcat cf. increase in seasonal yield including Missicn Basin with nc deficiency 1,640.00 602.00 Per acre-foot of increase in seasonal yield including Missicn Bv.sin mth 25 pea* cent deficiency 517.00 .-iNNUAL COSTS - TOT.lLS $233,000.00 $331,000.00 Per acrc-fcot of storage 4«74 2«04 Per acre-foot of seasonal yi-eld with nc deficiency 38,70 26.00 Per icro-fcot of seasonal yield with 25 per cent deficiency 23.30 Per acre-foot of seasonal yield includi ng Missicn Basin with no deficioncy 29,10 22. 5C Per acre-foot of se .sonal yield including Mission Basin with 25 par cent deficiency 20.50 Per acre-foot of increase in seasonal yield including Mission Basin with nc deficiency 109,90 37.50 Per acre-foot of increase in seasonal yield including Mission B-sin with 25 per cent deficiency 32.20 The anaiual costs per acre-foot cf yield listed in the above table are based en the assurapticn that the water users would pay the full costs cf the dam and reservoir v/ith interest charges at five per cent per annum and a forty year amortization period, .jiy grants frcn the Federal government for the flood a:)ntrol provided ^r any reduction in the interest rate through Federal financing my reduce these ccsts materially, Monserato Dam and Reservoir The exploration cf the Monserate dnm site sh^ v/ed that an excava- tion cf abcut 100 feet in depth v/culd be necessaly over several hundred feet of stream bed and that the right abutment was so fractured and disintegrated that a water ti git facing would be required over the reservoir face of the ridge. A preliminary comparison of the costs c f the Bonsall and M-nserate dams \iB.s xnade. This shovred that the Bonsall dam vrould probably be much less costly than the Honserate daLu Consequently, no detailed studies have been made of the costs of storage or of seasonal yields from the Monserate site. Flood C ontrol The operation of the 162,610 acre-foot reservoir at Bonsall for a seasonal yield of 14, 180 aorc-f oct vrould so regiraent the flow of the river that uncontrolled flows vrould pass the daiii only in seasons of major floods. The crest flows of these floods would be very materially reduced in pass- ing through the spillway^ An analysis of the estimated oncc-in'-250 year flood sho'ws that the passage of that flood through the spillway vrould have reduced its crest flow from 80,500 sccond-fcet to 53,100 second-foot, or about 34 per cent. The reductions in the crest flovrs of more frequent floods would be oven greater. CONCLUSIONS The principal conclusions of this investigation may be summarized as follo^/iTs: 1, Based on the period 1887-1935, the mean seasonal runoff from the area between rienshav/ Dam and the Bonsall daxn. site is 23,170 acre-feet. The rimoff from the drainage basin between the dara site and Oceanside is given in Bulletin lie, 48 as 3,370 acre-feet. The total mean seasonal runoff avail- able at Oceanside is 26,540 acre-feet, 2, The present draft of approximately 5,900 aorc-foet is approaching the maximum yield which may be obtained vri. th reasonable safety, 3, A reservoir storing 162,610 acrc-foct of vra.tcr in the Bonsall basin could have been operated during the period 1887-1935 to produce a seasonal yield of 14,180 aorc-f cet by taking a twenty-five per cent deficiency in the driest years. Probably 2,000 acre-feet per season of the inflow bolow the reservoir could have been conserved by underground storage in the Mission Basin. The total yield from the stream for the period would have been about 16,180 acre-feet per season. This would have provided a reasonably safe yield of 10,280 acre-feet in addition to the present draft, 4, Satisfactory foundations may be prepared at the Bonsall dam site Tri-th only a few feet of e::cavation on the abutments and a maximum of about 55 feet of excavation in the stream bed, 5. A reservoir storing 162,610 acre-feet of water in the Bonsall basin could be forTned by the construction of a dam 120 feet in height from stream bed to spillvray lip. Under present conditions an earth dam with a freeboard of twenty feet above the spillviray lip and the necessary reservoir lands would cost about 05,316,000, The annual cost would be about 0331,000 or C20.50 per acre-foot of reasonably safe yield or 032.20 per acre-foot of increase in yield over present draft, 6« The spillvrciy of the Bonsall dam can be so designed that the smaller floods nay be reduced to purely nominal flovfs and that a major flood such as might be e::pected to occur at an interval once in 250 years could be reduced more than one-third. 7, The Monscrate dam site is unsatisfactory because of the ex- cessive depth of river fill in the stream bed and of the permeable nature of the ridge forming the riglit abutment vMch vrould require an expensive impervious blanket on the reservoir side. The preliminary analyses of this investigation have estab- lished the suitability of the Bonsall site for the construction of an earth dam and have determined vathin reasonable liioits of error the pro- bable r\inoff vriiich vrould have been available for conservation during the period 1889-1935. However, the lack of sufficient technical help pre- vented the necessary additional analyses of reservoir operation and de- tailed estimates of costs vAiich if made might show increased yields and 8t. reduced costs per acre-foot of additional yield. Further analyses oould include, among others, the follovj-ing: 1. Estimate of the present losses from the underground basins through transpiration by natural vegetation in the river bed and the in- crease in yield vrhich could be obtained by the elimination or reduction of these losses, 2. Estimate of the increase in yield v/hich might be obtained by the reduction of the estimated evaporation losses through utilization of storage in the Bonsall o-nd Pala underground basins* 3. Estimate of the costs of spreading vrorks designed to increase percolation into the underground basins and of pumping plants strategic- ally located to utilize more nearly the full capacities of the underground basins. chapti;r II HYDROGRAPHY The San Luis Rey River is the most northerly of the San Diego County streams whose drainage basins lie almost wholly within the boundaries of San Diego County. Rising in the ?/arner Mountains at an elevation of about 5,000 feet above sea level, the river flows in a southwesterly direc- tion across the Warner Valley, skirts the southerly base of Palomar Moun- tain in a deep, narrow gorge and thence flo-,7s in a general westerly direction, through a series of valleys and narrows, to its point of discharge into the Pacific Ocean at Ocoanside. Its major tributaries are Pauma Creek, which drains the western slope of Palomar Mountain and enters the river several miles east of Pala, and Keys and Moosa Canyons, which drain the mesa lands south of the river and enter from the south between Monserate Mountain and Bonsall. The drainage basin above Oceanside, shovm on Plate I, "Drainage Basin of San Luis Rey River", has an area of 565 square miles, is about 56 miles long and has an average v;idth of 10 miles. The construction of Honsha^ Dam, which has created a reservoir of 203,600 acre-feet capacity at the lorrcr end of the Warner Valley, has effectively controlled the flo.; from the upper 206 square miles of the San Luis Rey River drainage basin. Only in the wettest years will any imcontrolled flows pass the Hcnshav? Dam. The lor/er 359 square miles of drainage basin, including the western slope of palomar Mountain nhich rises to an elevation of over 6,000 feet above sea level comprise one of the largest sources of undeveloped water in San Diego County. Full Natural Flow Estimates of the full natural florrs of the San Luis Rey River from the drainage basins above Henshaw Dam, between Henshaw Dam and "near PLATE X PLATE X R2E. R.4E. T.9S. 11. Bonsall", and between "near Bonsall" and Oceanside were presented in Bulletin No, 48. These estimates were based on all the available stream flow measure- ments and data on the use of water for irrigation and other purposes whl(5h v,'ere obtainable at the time those estimates were made. Ho'^evcr, an irrigated area survey, made in 1934-35, indicated that the irrigation uses in the area below Henshaw Dam had been underestimated in the preparation of Bulletin No, 48. For this reason, it has been necessary to revise the estimates therein presented. The revised estimates of full natural flow are presented in Table 1, Tull Natural Flow of San Luis Hey River". A comparison with the esti- mates presented in Bulletin No. 48 shows that this revision increased the estimated mean seasonal full natural runoff by 2;460 acre-feet. Available FIo tv All of the full natural flow, however, is not available for con- servation at downstream points. The Escondido Mutual Water Company, the Rincon and Pala Indian Reservations and numerous private irrigators have prior rights to the floT7 in the stream. The Rincon Indians also have a prior right to water from above the Henshaw Dam, which, when exercised, increases the doT7nstream flow by the amount of the return flows fron their irrigation. The Rincon Indians right, conceded by the upstream divertors, is to the first three second feet originating above their reservation. 11. Bonsall", and between "near Bonsall" and Oceanside were presented in Bulletin No, 48. These estimates were based on all the available stream flow measure- ments and data on the use of water for irrigation and other purposes whlcih vrere obtainable at the time those estimates were made. However, an irrigated atea survey, made in 1934-35, indicated that the irrigation uses in the area below Henshaw Dam had been underestimated in the preparation of Bulletin No, 48. For this reason, it has been necessary to revise the estimates therein presented. The revised estimates of full natural flow are presented in Tabic 1, Tull Natural Flow of San Luis Rey River". A comparison with the esti- mates presented in Bulletin No, 48 shows that this revision increased the estimated mean seasonal full natural runoff by 2;46C acre-feet. Available Flo ":? All of the full natural flow, however, is not available for con- servation at downstream points. The Escondido Mutual Water Company, the Rincon and Pala Indian Reservations and numerous private irrigators have prior rights to the flo"^ in the stream. The Rincon Indians also have a prior right to water from above the Henshaw Dam, which, when exercised, increases the downstream flow by the amount of the return flows from their irrigation* The Rincon Indians right, conceded by the upstream divertors, is to the first three second feet originating above their reservdvion. 12 TABLE 1 FULL NATURAL TLC'l 0? S'M LUIS KEY RIVER ORIGINATING BETft'EEN H!iI^ISH.•!.W D.M /JTO GaGING ST.'iTION NE J^ BONS.iLL Area cf Drainage Basin - 312 Square Miles : ?nll ■■ ' • Full Full ; Season • natural • Seascn natur al • • Seas, n n:::tural ' : flfW;i:i : flow- in • • f lev/, in ' • acre-feet , '• ■ acre-feet ' ' acro-feet • 1387-38 16, 720 : : 1903-04 6,380 : : 1919-20 : 14,600 : 1388-89 35 , 550 : : 1904-05 28,390 : : 1920-21 : 4,510 : 1889-90 51,200 : : 1905-06 65,790 : : 1921-22 : 72,9oC 1890-91 47,750 : •• 1906-07 51,460 : : 1922-23 13,890 : 1891-92 22,820 : : 1907-08 18,310 ' : 1923-2 4 : 11,430 : 1892-93 25,210 : •• 1908-09 32, 640 : : 1924-25 : 6, 120 : 1893-94 10 , 620 : • 1909-10 31,040 : : 192 5-26 : 20,170 : 1894-95 100,000 : : 1910-11 23,090 : : 1926-27 : 82 , 490 : 1895-96 7 , 180 : : 1911-12 : 9,320 : : 1927-28 10,280 : 1896-97 19 , 380 : : 1912-13 • 5,5.i0 : : 1928-29 : 10 , 580 : 1897-98 5, 850 : : 1915-14 24,840 : : 1929-30 15,410 : 1898-99 4,790 : : 1914-15 38,250 : : 1930-31 : 6,430 : 1899-00 4, 520 : : 1915-16 172,660 : : 1931-:;:2 : 56 , 430 : 1900-01 12,750 : : 1916-17 23,570 : : 193 2-. :3 12,760 : 1901-02 8,500 : : 1917-18 19,060 : : 1933-31- 4,910 1902-03 : 11,680 : : 1918-19 10,290 : : 193i-Jo 14, 330 : xB-year (1£ 587-1935) mean seas, nal ful] L natur i 1 ru n.rf - 2b, xc ; 13 In addition to its righis tc -./ator from abrvo Hensh^v/ D-^a, the Escondid. "utual Water Conpany :ilso nay divert the full cipacity :f itc canal, 70 second feet, vjhen available, from the water .rigimting botv/^en Honshaw Dan and the Esccndidc Intake. Based on the irrigated areas fcund in the 1934-35 census ^ind a consuraptivo use cf 1.5 acrc-fect per acre, private diversions fr.'m thj river ab've the head cf the propcsed Bonsail reservoir probably anount t; -.bcut 4,000 acre-feet per season. This estimate includes the l-mJs irri'^^ted by the Rincon Indians under their 3 second-f e-t right. The releases frcn Henshaw tc the Rinccn Indi Jis and the divorsicns by tho Eocondide LIutual V.'ater C.:upany xo depcnient on the surface runoff :f the river and vary therewith. ?r .c tic -'illy all the diversions by private irrigat.rs, hjTrcver, ai'e rn^-de by puraping frcn the river sunds and gravels and consequently :.iay draw .n the st-rage therein during dry seasons. In estimating the probable yield frcr.i a rcsei-v ir .t Bonsail under present crnditions all these factors must be c:.nsidcre^. C nsoquantly, the full natural flov/s presented in Table 1 have been adjust-d t c rif-rn to these conditions. The adjustnents for the Rinc n releases and Zsc-ndido diversions were based on the available reccrds f laily f lc.;s at the Honshaw dan site. The adjustzaents for liversicns by private irrigat rs T^ero cased on a full diversion cf 4,000 acre-feet every seascn. The adjusted fl:-..s at the gaging station near Bonsail are prosontei in Tabic 2, "Zstinated Hlin Off cf San Luis Roy River near B:nsall". These values represent the fJL"■^7S -.t. ich would have occur sjd had the present upstrean liversicns been nale during the peri d for which values are presented. Any additicnal develcpncnt increas- ing upstrean. diversions fr^n tho river will decrease the an.nnts avsilatle for use downstream. 14 TABLE 2 ESTIMATED RUNOl-F OF SAN LUIS RLY RIVER BGNS^IX DAI.: SITE Had present diversions been made in the past. Area of drainage basin - 312 square miles ■ Month Runoff, in acre-f 'eet 1887-88 1888-89 1839-90 1820-91 1891-92 1892-93 1893-94 : : Oct. 50 = : C : C : C G : : Nov. 390 '• 240 : 190 : 20 : ■• : Dec. 2,320 1,090 ■ 25,170 : 590 420 1,730 : : Jan. 3,390 2,270 • 9,000 280 : 680 : 1,330 1 , 050 '■ : Feb. 2,820 2,580 ■ 6,730 i 28,430 : 5,510 1,170 2,550 « : Mar. 4,370 14,960 '■ 2,300 : 6,400 2,570 : 16,440 1,620 • : Apr. 370 4,760 '• 490 : 2,370 3,940 2,060 460 = : May 1,140 = : 990 3,360 : 6C C '• : Jim. 470 ■ 420 830 : C ' : Jul. 50 '■ : 80 : ', '• : Aug. ' : C : ' ; Sep. ' • : 9 : : ' : Total ■ 13,690 27 , 340 : 45,930 ! 38,890 .17,750 . 21,500 : 7,410 • ' Month ] 1894-95 1895-96 ; 1896-97 ; 1897-98 ; 1898-C9 • ir'^.Q-oc ; 19CC-C1 '. jOct. : . ': : : C : • : ! Nov . : : C : : : : iDec. : 2,420 : G : : : .' Jan. 68,430 • 2,010 : : : C : : ^ ' ! Feb . 8,790 840 • 4,200 :1,600 : : : 6,18C. : ; Mar . 5,560 2,000 : 9,270 •;l,o9o : 570 : C : 1,240 : ! Apr. 2,720 170 : 730 : 230 : 770 : 770 730 : JMey 280 : : : : 10 : 780 : 370 : ! Jun. 60 : : : : : ; : ; Jul. : : : : : : JAug. : : : : : : .' Sep . ! Total 88,260 5,020 : ' 14, 200 i 2,920 ': 1,350 ': 1,550 ': 8,520 : 1 \BL2 2 (Coitinucl) 15 : Mcnth RU!Kfl , in -cr;- r.j..,t : ig:i-02 ; 1902-03 ; 19C3-04 ; 1904-05 ; 1905- -'6 ; 19:6-.. 7 ; 10u7-.j3 : .' :^ct. • : : : .: : : : :n-v. • : : : : : 10. : 300 : ;d..g. ■ : > ^ 4 C : .: 390 : 2,650 : 72. ; J ,r. . • : •: : .: c350 : •.13,^30 : 2 , 460 ; ; Fob , • 70 : 330 ; : 4,. --.00 : 1,000 : 4,320 : 6,411. '. :.rar. 1 r)-\ 2,790 ; 300 • 12,310 : 33,920 : 10 , 370 • 2,3.0 ; .' -Vpr . ; i,;7o ^ 3,930 ; 1,710 2,030 3,670 : 4,G20 ' 790 ; " i.^-v 70 400 470 ; 2,730 4,330 : 1,610 '■ 270 ; . JU!.. ; 0. 190 : 520 : 1,56: : 430 ; ". Jul . ; 300 : ; ." .vU,-? . • ! : 50 : '.Soy, ; ; ^ ' v.: : \J iTctal •. 5,530 • 7 , 450 • 2,670 ; 22,390 : 56,120 43,330 13,75. ; '.Mcnth 19C3-U9 ; 1909-10 • 191v:-ll ; 1911-12 : 1912-13 1913-1-1 • 191 .-15 ; :'oct. • ^1 ^ V , JN.v. 210 '. '- s^ :Doc. 3,650 720 ! : vO u ; Jan. 6,790 . 15,5o0 . 1,840 ! : 960 ; 12, 57; : •Feb. : 10,910 ; 2,100 : 6, 1'io • 50 : 65o : 9 , 350 ; 35,310 ; jl^Iar. 4, 55v. '. 2,450 1 6,570 ! 2,970 : l,74w : 5, 530 • 10,300 ; i-Pr- : 2, 3v0 ; l,5cO ; 2,3c0 '. 1,070 : 790 : 1,70^ : 3,960 ; r^^-y : 700 100 160 .' 2, 440 : : 1,570 : ^,^^^ : ; Jun . . ; ; : '• 3o ■7 1 ,■ ^ ' ":Jul. [ : : ; 700 :--u-' . ; ; : : • c [ •S J. . ; ; : : ! ^ • .'Total . 25,750 .'25,460 ; 16,020 ; 6,530 : 3,130 : 19,740 ; 76,12.0 ; '.Month 1915-16 = 1916-17 • lC17-ld ; 191 -- 19 : 1919-20 : 1920-21 : 1921-21 5 ;cct. • ■ 1,370 : : Q • ^ ^ ;n:v. • : 1,32: : 390 = 1,290 : -J : "^ : : ;D':-c. ; 910 : 1,370 : 1,130 = 1,990 ': 3 : 15, 310 • ;jr.n. • 131 , 210 : 4,250 : 1,6:;0 = 1,300 : 1,16: ; : 8,7i0 : ."Feb. • 14,540 : 6,750 : 590 '• 1,650 : 1,7- i 300 : 6,0;0 '• ':{T. '■ 6,990 : 2,L10 ' 9,310 ■ 1,270 : 1,1^0 : 560 : 15,300 : '. -'^P" ■ 2 , 510 : 1,150 : 670 ' 660 . 2,920 '; 6'iC : 7,02: '■ .'M".y 1,240 : 1,6X : 670 '■ ISO .' 2,390 ; ^xO : 1,7:? : \ Jun . 1,350 •• 1,100 : 310 '•■ ': 1^ • c : 1,1-xJ ' ;jui. 1,130 : 1-40 : • : : 320 : ■ \\X-! . 590 : : : -Q : :' 2 • <- * •Sov. ] 5!y0 : : : : ;Tctal "160,970 = 21,940 5^5,250 = G,340 : 9,400 : 2,24v : 56, 530 '• T.3LE 8 1« (C atinu-i) : Month Runoff , in aero-] fcCt : 1922-23 192 3-24 1924-25 1925-2 6 1926-27 1 • ■ ■ . - ■■ ■ ■■ 1928-29 icot. : : : : N:v . : 520 : .0 : : : : Doc. : 3,120 : 1,350 : 1,050 : 880 210 : 640 : Jar*. ; 2,180 1,340 : 1,090 : 910 • 780 : 1,640 o50 :Fob. 3,980 : 710 : VX) : 1,500 70,450 2,510 1,620 : :r.ir. : 2 , 240 : 2,320 660 : 870 2,650 : 1,350 2,010 : .T-pr. : 2,030 : 2, i40 620 : 11,350 • 1,130 590 : 2,100 :I-My -450 : 350 : 470 390 : 370 : 350 : Juiic 60 : 10 : 80 : 70 : : July ; : o' : : Aug . : : : : :Scp. : : : : Total l-i,5£0 : 8,520 .4,J.50 : 16,060 75,680 : 7,100 : 7,223 '. Mcnth 1929-30 1920-31 1931-32 * . 1932-33 1933- ;si ; 193 -.-3 5 . Lloan .'Oct. ; !kcv. ; ■^ ^ ; !dcc. ! 2,420 ; 1,030 430 30 . Jon . 1,460 1,230 . 1,980 . : 2,790 750 ' . 2,720 JFc-b. ! 1,090 2,050 ; 33,990 ■ ; 2,010 940 : 4,070 !:.i-r. ! 2,210 640 '. 5,750 ; i,2oc. 7cO ! i,d60 .Apr. . 830 380 ! i,a.iO ; 920 320 .' 1,110 '.Uzy '. 4,360 230 '. 830 ; 1,25C 16C . 330 '. Jun . : 390 30 ! 290 ; 160 !ju1. ": 30 : .' \ ! 10 .Aug. : -40 .' ! ; ; 60 .Sep, I ; ! : ^ ; ; ! Total : 10,980 4 , 610 47 , IJO : 9,410 : 3,410 :_i:,190 : 23,170 17 Flood FlcTie An analysis ^f the probable flocu flc-,7S en San Diegc Ccunty streams was presented in Bulletin No. 48. This analysis inclut'.ed the S n Luis Rey River oiiJ. inlicatci probable flood flc.vs as listed in Table 3, "Probable Size send Frequency ^f Flood Flev/s n the Son Luis Rey River at Oceans id c. " TABLE 3 PROBABLE SIZE AND FRSQUSIICY OF FLOOD FLOV.'S ON THE SAN LUIS REY RIVER AT OCSANSIDE FROM 'IHE DRAINA.GE BASIN BELOV/ HENSH.IW BiM. Area of drainage basin - 359 square nilcs . Frequency v;ith T^hich ; floods nay be expected to cccur Mean daily fir", in seci^nd feet '■ Crest flov;, in SaCi-n-.".-f :;t-t : Once in 2 5 years 17,000 ' 2b, 600 : Once in 50 years 24,900 ■ 41,800 : Once in 100 years : 31,500 ; 58,000 Once in 250 years 47 , 900 ; ac,5oo 18 CHAPTER III COIISEKVATIOIT I^llD FLOOD CONTROL Present Development The San Luis Rey River in its course from Rincon to the ocean passes tlirough a series of br^sins which liave been filled -with sand and gravel to depths ranging from 50 to over 100 feet. These basins all provide under- ground storage v;hich may be utilized to supplement the natural flov; of the stream during dry periods. There are three major basins: the Pala Basin from Rincon to Honserate Narrows; the Bonsall Basin from Monserate Narrov;s to Bon- sall Narrows and the llission Basin from Bonsall Narrovrs to Oceanside, An independent study of the available undergroimd storage in these basins vras not made in this investigation. However, the United States Geological Sur- vey mo.de such a study * in 1914 and 1915 and a reconnaisance survey vras made by the Division of "".Yater Resources during the San Diego County Investigation reported in Bulletin No. 48. From these studies it seems probable that the underground storage in the Pala Basin is at least 20,000 acre-feet, in the Bonsall Basin 21,000 acre-feet, and in the l/Ession Basin 12,300 acre-feet. The 1934-35 crop survey p\\blished in Bulletin No, 48 shov;s that at that time 1360 acres vrero irrigated from the Pala Basin. With a consiunp- tive use of 1,5 acre-feet per acre the present draft on the Pala Basin vrould be 2,040 acre-feet per season. 1,233 acres of orchard, vineyard, truck crops and alfalfa and 1,580 acres of field crops were irrigated in the Bonsall Basin. With consumptive uses of 1.6 aore-feet for the former and 0.5 acre-feet per acre for the latter, the seasonal draft on the Bonsall Basin v/ov.ld be 2,765 acre-feet. 1,499 acres were irrigated from the Mission Basin. With a consumptive use of 1.6 acre-feet per acre the irrigation *1. United States Geological Survey, Vfater^Supply Paper 446, Geology and Ground waters of the V/estern Part of San Diego County, California by Arthur J, Ellis and Charles H. Lee, 1919, 19 draft at present ^ould be 2400 acre feet per season. There are also the drafts of the City of Oceanside and the Carlsbad Mutual ^"toter Company rhich in their maximum years have amounted to 1200 and 2300 acre-feet respectively. The present seasonal draft on the Mission Basin therefore TTOuld be about 5,900 acre- feet. This draft, 5,900 acre-feet, from the Mission Basin, is about the safe yield from the 12,300 acre-feet of storage in that basin. The total flow past Bonsall during the dry period, 1897-1900, is given in Tcble 2 as 5,S20 acre-feet. The corresponding flor; from local drainage is given in Bulletin No, 48 as 1,200 acre-fcct. Assuming the basin full at the start of the period the total rater available \rould have been 19,320 acre-feet. Under present conditions the draft during the three year period would have been 17,700 acre-feet, leaving a surplus of only 1,620 Gcre-feet to flow into the ocean and prevent salt v/ater intrusion in the gravel beds. The total underground storage in the three basins is estimated as about 53,300 acre-feet. During the dry period 1895-1904 the total runoff at Bonsall is given in Table 2 as 49,300 acre- feet. The runoff from the area below Bonsall is given in Bulletin No, 48 as 7,400 acro-feet. Under present conditions, assuming the basins full at the start of the period it is estirar.ted ttat an average seasonal flow of 12,200 acre-feet yrculd have been available. The mean seasonal flo-.r at the Bonsnll dam site as shOTHi in Table 2, based on the 48 year period 1887-1935 is 23,170 acre-feet. Therefore, it is apparent thrit full conservation of the flood floTv-s Trill require the provision of additional storage space. Under present conditions each user pumps from the underground basins \7henever he wishes and locitos his pumps vdiere ever it iKiy be most convenient. At present, replenishment is from the uncontrolled flov: of the stream and 20 even in dry years much water is wasted into the ocean. The full utilization of the underground storage will require adequate spreading; works to obtiin the naxinum possible recharge fror.i the flow of the stroan and an orderly Aistri- bution cf pumping plants so that all portions of the underground reservoir r.;ay be used. Reservoir Sites The analyses presented in Bulletin No, 48, Table 2C , indicated that approxinately 133,00^^ acre-feet cf storage c.ipacity would be needed to conserve the flo" cf the San Luis Rey River belov; Henshaw Dan. A reconnaiscnce cf the drainage basin showed that this amount of stora-^c could probably bo most easily obtained by reservoirs either in the Bcnsall basin, above a da:i built near the present State highway crossinf^, or in the Pala Basin above a dam built in the. Monserate Narrows above the San Luis Roy Ranch. Other dam and reservoir sites Tjere fcunl cu Paur.ia Creek ;and on Mcosa Canyon. This investigation provided for surveys cf both the Bcnsall and Mcn- serate Reservoirs. These surveys wore nadti by plane table at a scale cf cne inch equal tc 4C0 feet with 1j f c ^t contours bein;^ drawn in. The resultant tcpoGraphical iiaps are shc7»n in Appeniix :>., "Topography of Bcnsall Dansite and Reservoir" an:, in Appeniix B, "Topography cf Monserate Dnnsite ani Reservoir". Area and capacity curv..s for the Bcnsall reservoir are sh^Tvn on Plate II, "Areas and Capacities cf Bonsall Reservoir" and for the Mcnserate Reservoir en Plate III, "Areas aid Capacities of Mcnserate Reservoir". The areas and capacities at 10 root intervals fcr each reservoir are listed in Tabic i, "Areas and Capacities of Bcnsall Reservoir" and Table 5, "Areas and Capacities .f Mcn- serate Rcservcir". A c laparison c f the .\ata in Tables 4 and 5 is presented in Table 6, "C'^Tjarison cf Flooded Areas and Capacities .f -^cnsall and Mcnserate Reservoirs". This comparison sirws that any .^ven ancunt ^f stt-ra^c in excess of 43,000 acre- feet ray be obtained at Bonsall with a lower dam than -.xull bo required fcr the sane a:ncunt cf stcra:e at Monserate, PLATE H to O) u u OJ i 1 ! CO — \ Lu cr V PACIT ERVO \\ o o _ \ \ \ \ ND CA OF L RES — o \ \ — \ N — - \ \ \ \ < ^ — ~ \ \ % < ^ LJ O - \ \ \ \ v — k- ^ \ q: do _ o — \ \ < ^ o \ \ o \ * 1 [ — — — t\ 1\ — •A ^A C;\ \ ■y\ ci\ — — ^ \ — o o o\ \ o \ \ CM — 1 \ N \ \ V — \ \ \ \ \ \ \ O \ \ %. o N \ — \ \ \ \ \ — ^ k \ — s N — ^, I ^ , — ~ 1 1 — 1 — 1 f— ,^1.- 21. o o o cS o o o -♦-' o CD o 0) U) ^- Q) t_ (-> (^ o o (^ o o o o o cT o f>4 o o o 00 o o o ULiniBp cqcn 'P^i ui aDi2;jnsJ3^eM jO uoaeAa)^ PLATE HE T.IBLS 4 ;jRKiS :m) capacities 0? 30NSALL RESERVOIR 23 Eli-vaticu cf Area of Ca;acity cf water surface, water surf jlcc. ' reserve ir, [ in in in \ feet 1 acres 1 acre-feet *U.S.G.S. Datun ' 120 '• • 13^: 35 181 • ; 14C 133 ' 923 • 150 278 • 2,951 • • 16o • 456 ■ 6,592 • • 17C 771 ; 12,612 ; • IdO 1,026 ' 21 , VC ' • 19, '• 1,3 41 ■ 33, S-iO * • 20. ' 1,830 • -^9,170 \ • 210 2,329 ' 69 , 997 * 220 ' 2,3X • 95,734 • • 230 ' 3,342 ' 126,691 ; ■ 240 ' 3,840 • 162,605 ; 250 4,346 ■ 203,515 ; • 26:' ' 4,879 ' 249,636 T.-iBLE 5 ARE:iS .iIID CAPACITIES OF MONSER'.TE RESERVOIR 84 : Eiev.-'.ti.n cf : Area c f Ca::'icity .f • : water surface, : water surf ice, reserve! r, • ; in i irx in ' : -feat ! acres ! acre-feet , * : U.S.G.S. Datun ; 273 ! : 230 : 6 6 : ! 290 : i4i ! 737 ; ! 300 ! 306 2,960 : 310 \ 491 6,919 : 320 ! 603 ! 12, 307 ; 33: 735 19,294 : 340 ; 972 23, 1^8 i 350 ! 1,139 33,630 : ! 360 ! 1,413 51,379 : 370 ', 1,676 ! 66,365 : '. 380 1,966 2,179 35,069 : ; 39C 105,793 : 400 2,473 ; 129,053 : •iio 2,723 ! 155, 04S : ! 420 2,962 133,433 J 43 J ; 3,192 214 , 263 : ! 440 3,414 247,294 : 45; . 3,621 • 232,437 .' E5 T.\BLE 6 COMPARISON OF FLOODED ARE.iS AND CAPACITIES OF BONSALL AM) MONSERATE RESERVOIRS Depth of water Flcodei area, Capacity, . in in acres in acre-feet . feet Bonsai 1 • Monserate Bens all Mcnserate : . reservoir reserve ir reservo ix reservoir t 10 35 : 114 131 479 ;- 20 ; 133 27C 923 2,385 : 30 278 452 2,951 5,976 : 40 453 573 6,592 11,212 : 50 771 746 12,612 17,763 : 60 1,02 6 92G 21,7v,o 26,193 70 1,341 1,099 33, 34 . 36,393 ao 1,830 1,361 49,170 4:;,6JC : 90 2,329 1,624 69,997 63,566 : 100 2,338 1,910 95,784 31,194 : no 3,342 2,129 026,691 1.1,485 : lao 3,840 2,413 162,6:5 124,166 : IX 4,34^ 2,674 203,515 149 ,652 140 4,379 2,915 ■ 249,635 177,615 1** • — •<-■.-■—- 26. ki \': ^Tl 09 O fc» rH r^ □C M -H -r^ H « d ^ KM « U §K SO » P. 55 cn -p ^ M C CO a hJ a < 0) V Q SS +> -P ij CO CO e :) » • -a > s 27. Hf \^ Vd > C 3 I 28 Evaporation In determining the probable safe yield which nay be obtained by storage of excess -aater in surface reservoirs one of the major factors is the probable loss by evaporation from the water surface. This subject was discussed quite fully in Bulletin 48 and consequently \rill not be re-dis- cussed here. In estimating the evaporation from the water surface of the Bonsall resei-voir, the sar,ie rate of gross evaporation, 60 inches per sea- son, was used as vms used in Bulletin 48 for the I/Iission Gorge Reservoir on the San Diego River, Both reservoirs lie in much the same position in relation to the ocean and the moxintains. The rainfall v/as based on smaly- ses of the records at Oceanside, Vista, smd Fallbrook, Yields Analyses of the probable safe yields v;hich might have been ob- tained frrm the San Luis Hey River during the 48-year period 1887-1935 ■under present conditions of upstreaia development by the construction of reservoirs in the Bonsall basin storing 49,170, 95,780, and 162,610 acre- feet have been ms.de. These analyses v:ere made on a monthly basis by the methods described in Bulletin No, 48, The results of these studies are shown in Table 7, "Yields of Bonsall Reservoir on San Luis Rey River". TABLE 7 YIELDS OF BOhSALL RESERVOIR ON S:JI LUIS REY RIVER "Capacity of Reservoir, in acre-feet 49,170 95,780 162,610 : Safe Yield, : in : acre-feet Yield vdth 25^ Deficiency in ; acre-feet : 6,020 : 8,530 : 12,730 14,180 29 An cjialysis v.as also made of the yield -.vhich could be obtained from the 162,610 acre-foot reservoir by taking a doficicncy of 25 per cent in the seasonal draft Trhenevcr the storage in the reservoir ras loss than 30,000 acre-feet on May 1st, The yield indicated by this analysis, also sho'.Tn in Table 7, and the operation of the reservoir during the 41-year period, 1894-1935, is shov.n graphically on Plate IV, "Operation of Bonsall Reser- voir on San Luis Key River". Of the total inflo" during the period analyzed, 941,650 acre-feet, only 94,180 acre-feet or 10,0 per cent, were xrasted through the spillway; 361,500 acrc-fcet, 38.4 per cent, rere lost by eva- poration and 485,970 acrc-foet, 51.6 per cent, T.-cre conserved for benefi- cial use. At present the entire drr:ft, 5,900 acre-feet, from the San Luis Rey River bclov; the Bonsall dam is made by vrells in the Mission basin. Should the Bonsall dam be constructed, the City of Oceanside and the Carls- bad llutual '^ater Co. might connect their distribution systems directly to the reservoir thus utilizing the head provided to reduce their pumping lifts. Or the Bonsall reservoir might be used as an equalizing reservoir releasing ^ater to replace that pumped from the Mission Basin. Under the latter method of operation vatcr levels in the Mission Basin could be held comparatively lo.; during the vzintor season, thus providing space for the conservation of the runoff from the area belov; the Bonsall dam. In Bulletin No. 48 this is estimated to amount to some 3,370 acre-feet per season on the average v/ith a seasonal variation of from to over 19,000 acre-feet. By utilizing the 12,300 acre- feet of space in the Mission Basin for the storage of this flow an additional yiold of about 2,000 acre- feet could probably be obtained. The Mission basin would be filled from the Bonsall PLATE 12: PLATE IZ 160,000 140,000 120,000 loaooo ■ 80,000 ■ 60,000 40,000 20,000 LEGEND Usable run- off 1915-16 68,990 Acre-feet Wasted run.off['''-'' ''■''° ^'''-'''' ^ Draft Evaporation VS/ Stored water -" — L Usable draft plus evaporation Acre -feet CAPACITY OF RESERVOIR 162,610 SEASONAL YIELD- 14, 180 DEFICIENCIES 1901-02 2,120 1902-03---- 3,540 1903-04 3,540 1904-05 3,620 1905-06 1,170 WASTED WATER f^m OPERATION OF BONSALL RESERVOIR ON SAN LUIS REY RIVER STORED WATER • USABLE RUN-OFF EVAPORATION w$M \mmmm^mm^^i^::m: II Mm ' '*T'it;vi*i*^' ^ :-;i;:::.';lt;v:'i:-v:^-; ^J:^S^■^:.!Ii:-l; ^^^:i::v^t::;.;^t' 31 rcscr-^-oir each spring oStor vho wjitor rmoff had occurred thus mcUcing souc saving in evaporation losses. Because of the lack of sufficient technically trained help, no further detailed ajialyses have been made. It is probable that oji in- crease in yield could be sho\-m by doteraining the savin:;s in prcsoirt transpiration and evaporation losr^cs fron the reservoir areas vmich would bo flooded by the reservoir and from the surface areas of the under- ground basins if the rrater tables therein should be lowered. Flood Control Should the 140 foot dc^:i be built, the operation of the reservoir to yield 14,180 acrc-fect seasonally vrould autonatically store the vrr.ters of all but Kiajor floods. The operation studies sho->T that spill past the dan vrould have occurred in only txrc seasons, 1S94-S5 and 1915-16, in the period from 1894-1955. In the first of these seasons only 25,000 acre-foct u'erc spilled and in the second 69,000 acre-feet vrcre spilled. The flood of January 27, 1916, the largest of v.-hich flov: records arc available, vrould have passed through the spillvreiy vdth a laaxiimm f levr of only 16, 900 second- feet, about thirty-seven per cont of the maximum f lov/ which vrould have occurred under present conditions of upstream development. Assuming the reservoir filled prior to the occurrence of the flood the crest of the estimated cnce-in-250-year flood would be reduced more than one-third in pasci'ig tlirough the spillvra.y. The reductions in crest flov; caused by the passage of these t\TO floods tlirough the spillv/ay are shewn graphically on Plate V, "Effect of Bonsall Reservoir on Flood Discharge". 31 reservoir each spring oStor the vr^ntov rmoff had occurred thus rarJcing soiAc saving in evaporation losses, Booause of the lacl: of sufficient tochnica?.ly trained help, no further detailed analyses have been made. It is probable that an in- crease in yield could bo sliovm bv determning the savings in prcsoirt transpiration and evaporation losnes from the reservoir areas uhich v/ould be flooded by the reservoir and from the surface areas of the under- ground basins if the vratcr tables therein sl.ould bo lorrored. Flood Control Should the 14-0 foot dojTi be built, the operation of the reservoir to yield 14,180 acre-fcct seasoiialiy vrov.ld automatically store the vnr.ters of all but major floods. The operation studios shov: that spill past the dan vrould have occurred in only tiro seasons, 1894-95 and 1915-16, in the period from 1894-1955, In the first of these seasons only 25,000 acrc-foct i?erc spilled cind in the second 69,000 acre-fcct iverc spilled. The flood of January 27, 1916, the largest of v;hich flov: records arc available, vrould have passed through the spill'.my vath a laaxirauiu flow of only 16,900 second- feet, about thirty-seven per cent of the naxianiun flo^v v/hich vrould have occurred under present conditions of upstream development. Assuming the reser-zoir filled prior to the occurrence of the flood the crest of the estimated once-in-250-year flood vrould be reduced more than one-third in pasGi>-i^ tlirough the spillvray. The reductions in crest flov; caused by the passage of these tvro floods tlirough the spilliray are shewn graphically on Plate V, "Effect of Bonsall Reservoir on Flood Discharge", PLATE 3Z:32. 80,000 36 48 Time in hours ESTIMATED ONCE IN 250 YEAR FLOOD Reservoir full at start of flood I c o u CD o 40,000 20,000 Crest flow 46,200 'Sec;fi Natural flow Reduction in flow 29.300 Sec.-ft. 637o of natural flow Crest discharge' 16300 Spillway/ discharge 12 48 24 36 Time in hours FLOOD OF JANUARY 27, 1916 With deductions for present diversions, Operated for conservation of 14,180 acre-feet per season EFFECT OF BONSALL RESERVOIR ON FLOOD DISCHARGE STORAGE 162,610 ACRE- FEET u<,l CHAPTER IV BONS.MI. DA'I AND RESERVOIR The Bonsall Rosorvcir site is loc.tcl in Soction 4 and 5, T 11 S, R 3 U; in Soction 12, Li, 15, 16, 19, 20, 21, 26, 27, 23, 29, 30, 31, 32 ani 33, T 10 S, R 3 W, S. B. B. ani M, ; and in the Monser&te Grant. The main lai site is in the SW^ cf Section 31 and an auxiliary :lTr.i is i n the M^ of the 3ar:e sGcticn. TopOj^ra^ic surveys anl raps of the dan sit uS have been r.iaic at a scale of ono inch equals one hundred feet with a contour interval of five f uet. These LEps arc di.wn in Appendix "A" Topc,-;raphy of Bonsall Daiu Site and Reservoir. Geology A f^eolcgic stuiy of the dam site -jas malu during this invjstir3ati."n. In the ocursG of this study filrut 1553 lineal feet rf trendies 2.5 foet 'rale by fron f ive tc fifteen feet in depth c.tlI 6 test pits six by six by from 10 to 12 feet deep were lug; 298 lineal feet . f thi-oo inch lu "or holes were bored in 13 hies; a six by six focttunncl 3o feet Ion: vis lu - in the ri^ht abulnent anl 4 t-jelvo-inch. wells were dr-'Mol -"n thj riTir bcl to depths of fron 27 to 58 foot, .i tctil .f 177, L fyct cf .Toll -./ere drilled. The locations of thoso varicus wcrkiivis are slrirn en the topographic nap of th-. dan sites in Appenrlix A. Profiles s\- •- "rr- -n . .-L-Iissifi cations -f the materials frund are also sh. wn in Appei.^- i-c A. The B.nsall dai site is located ,;n the Sun Luis Rey Rivor at a point whore the stream has cut its channel thru^. t; e :: rthwestern end of a snail ran^e kn-rvn as the San Marcos Kjuntains. Gv^hjr Cur.ycn T/hich drains the northeasterly slopes cf tiicse mountains and enters the reservoir basin ab:ut one half mile upstream frcn the dxi site is the only depression cf any size between the dan site and Bonsall tvK iiilos upstream. Active faulting has not been recorded in this area but i±.cl:s from distant 3-1 I faulting arc often felt throu-^out northern. San Dioy County. The courses cf Gcphor Cinycn and the sr;tiller canyon opposi te nay havo been lotcmined by a local fnult. Another r^ay run down the laft si-\o .cky cuter, js in the vicinity of the dai.i site but t.: st cf the area is ccvorci with about a foot cf soil uni su;ports a Ti *crcus- ^^rowth cf brush. A-.7ay fpj'r.: the stoepor silus jf the river canyon, the rolling hills alon^ both sides cf the river bank are cultivated. The -granite is rather poor in quality arU en the sui-fcce it often exiiibits spheroiial \7eatherin;j. In this type of weatherin{j there is much iisintei^'r-'tici. arouni harl ncdules of reck cf varyin- size. The ri 3ht siie cf the river in tiij vicinity cf the -lori site shcvfs nurierous weathered rock uutcrops, end at the axis f the d;iia site there are scnc hard bouliery nasses strewn along the hillsides. The left sidu :f the rivor in the vici- nity .f the lec.i site sh- t;s but few harl rock outcr:;s alonj its upper v^rtion, but there is quite a caitinuous outcro,; or har'. r. cl-: OTterdin^ beyond the linits of the da.a site belcv, the elevation of thu p.-e-sent hiihinay. S xcavr-ticn At the j.c;..i site the river be.; is -b, ut fi^-f hundred foot wile, a comparatively level bod .f sand and, except for a 'ihrrov lew v;ater channel, over-iv-Tn Tlth 77illo\/s. The lino of joi^ctdca of b.i-'lsi'-- an^ river bed is ^;70ll naikcd b, th by tcpo^ra-jhy and by vc-etal c- '-r, / . ^J l3 vrore ■rilled in the river bed. The lo ;s cf theso v/olls are ;iv-jr. ...••. : \\\o 3, "L. js -f Wolls Drilled at Bens all Da-. Site". Those Ic:^ ir lo. h^rd -ranitc shcul.: be encountered at an olev-ti.-n f -.Dcut -^o Toe. -ocve sc- level, ab;.ut 50 feet bel.TT the low p>.int in the present river chv.i-xol nnd th^it the old channel is pr. bri)ly ccntly rounlo: r-.ithGr tkm a sh irp "V- shaped .-cr^e. 35 CO g 1-3 EH S3 O Eh p to O CO o 1^ (U ■p • rt c 0) rj ■P Jh r-t •H ho To TJ '"H U3 c d P< 0) C (AJ rf t< hfl 10 c • r-i I/! tm O Pi o '« ft hfl ^ • t< rH a > » O XI l-H ■J > .t3 cd o p. r-H rH •H B rH 0) c; iS W « m lO o « te -i-> • • • • • . CD o rH ro f~- LO ^ 0) a ,£2 a Td • 1) > > o o u o r-l •H n o o ri la w « rt 0) m rH i-H OJ £5 KO U3 KN -P • k m • • - Q) o o J- in CO ^ 0) J- Lr^ LT. :r^ +J tH P. 0) c tt -^ rH 0} •H o C d C OJ rf (-> rf CM rH U) M> hfl • • u u o > 0) HI -S Iz; 0) t> +^ r-{ •rH d c3 rH H K > K rH .. +5 •H § Pi r-f M 0) 3> ■p X} > x! •H rH -*- d a 0) c "Kj a u 10 w CO • rH o tiS O u u o ft O hO ^ • u u S TJ > Q) -p o =" b ,-H r-i • H 03 OJ 5 ^ (U W « 1= Q m X !3 ■p r^=" . 0) UD CVJ CO ^ ^ Xl sD r^ ft CM C\J OJ CM CM 0) C .. a -H • • • • .. .. " .. .. Tho cstinatcd bei iv ck liuc is 3hc77n .n the prcfilc in Appom be .1. The laterials of tho valloy fill aro 1 or ;'ely riv'.T tian's -ind jravols i?hich ccul". be o-?.sily oxcivat d. The rijht .ibutroent cf thu dau is locatcl un a ariall hill rising tc an elevation of 2i ;■ feet ab ov.j sea level ^iiich in olijhtly hi jbor than the rest of the lew rid^^e whi ± fwTus the ri ^t bank . f tho ri;sarvoir . The tovo:;^a";'hy is rourklod and tht' slopes are oven Mith n. sudden breaks. The s\irf,.ce sh^ss nurierous .-;;ranite bculders, the ;_jrcduct ;.f spherL/idal ■:7eatherin,- . The trenches, test pits, ^r.l tuimel ;7hich sjore du..; in this abutucsnt show an averaje ..f about one fe.t jf soil r.j..;idly chan.jiaj to a coarse disintcjrited granite in place. The di sinto -.ration is rather deep. S •hcrcii'.al bculders in .:lace were encountered in the ri ^ht imt.ient tunnel but very little l:ar^ reck was fi.und in the ri^ht abut ..cnt exploratory trench. The disintcsratel bed rock, hcwever, conscliiates quite r;,pidly and at deptiis of about four feet the original structure f the r^ck in quLto api-a- rent . This hill provides a satisfactory abutiaent f c r an earth dai. The top foot cf scil which supports a nederately heavy growth -.f brush shcull be stripped and wasted. Under the irnpa-vicus section cf the daa excavation should extend through an additional three feet. The naterial which will be excavated is suit dale for use in the ±>m stre.xi section cf the dara and may be suitable for use in tho inpervious section. The left abutii^nt is a small rounded hill stan..in: out alaic as a tcpcsra;hic feature. It is unifcmly rounded on all side.-; with no den breaks in the slopes. The foot of this hill sbuTO an almost continue outcroppinj of lar. isr=-. nite which appears in the left bai.k of the river bei upstreari f rcn the daa as a gently sloyin j shelf o:vere.. with a shallow layer of soil. The u..por part of the hill is deeply weathered an\ sh .ws n. .ut- crcps cr boulders en the surfac. Bedr ck is exposed alo^- the entire length SU-- ;us 37 cf the present highway cut :n the left abutmont. Most c f the bed r. ck is soft and decomposed but there is onu- z ne of hard dark cc Icrod t^ranite crossing the road cut *ich so ens tc line up with the hard rcck found in the exploratory tunnel en the ri iit ±utn.ant of the dara site. On the left abutHEnt stiippin-; should be carried t."^ n depth ^f cno foot and the excavation uncler the iiapervioUs section of the dam dioild bo carried about three foet deeper. The spillway fbr the dam r.H y ;sss thro vrja. the j''>p rtiich separates this hill from the nain boiy cf the ran::3. This pass crests at an oldvati;a of db cat 225 feet «bcvu sea level. Tost Pit No. 7 which was dug in the lew porticn of the 3 cp showed a soil depth ^f abvitt dciht feet. Trench N . 5, however, shoTred that a relatively narrcYi depression in the bed rock separa- ted the left abutnait knoll fronthe main hills. At this p^int the soil depth reached a mximun of 16 feet. The alluviur'. in this itpressicn con- tained sono water worn naterial indi eating that an eld stri!';U channel nay have been eroded alon^ this possible failt line whi cli iras previously su-^- gested OS laving passed, through the spillwai' site. At the bottcm cf the trench the r~ck was fairly hard and seemed tL be continuous. From the evideice exposed in the tra.ch, it is believed that a satisfactory founda- tion fcr an Cgee spillway will be fo Lxd at a depth a" from ten tc fifteen feet below tlie present surface* For a distance cf approximately three-quarters r.f a nil£ upstroaa from the main d xi site the rieht bank cf tho roservoir is fcicod by a lew chain of hills varying in elevation frcn 25C to 275 foet above sea level. Cpposite aophcr Canyon this low ra3--:e turns away from the river and forms the western bank cf a snail canyon, the course of rhich -ay have been deter- mined by the local fault ;reviously su^i-osted. Alon;2 this c anyon the ridge cro::s in two places t. elevations .f dJout 21. feet abrve sea level. Any reservoir which takes advant^e .f the full heifjat of the abutrsnts at the 30 nain dan site will require auxiliary iacs alcE/, this rid-o. Tho ni.:o is unifcmly rcundcd and rolitivoly steep on the river side but slopes 3ently away on the side opposite the river. The crest ani j^ntly ro llin3 si ;:o3 have be^n clearer', aal a lar 30 .rart cf the cleared area is -^ipci fcr irri/3ation. The character cf the raaterials in the rid^e anl on the \butnent3 cf the auxiliary dxi sites has been explcred vdth 13 au^^I^ hclcs and c ne test pit. The Iccatione of these borings, shrwn en the topographic na ; f the dxi site, an:i a profile cf the rid^e shosrini the natcrials enccuntcxeJ in the au^ur borings ani Test Pit ^c, oareshcvai in Api«nd ix A. The soil Icpths alon- the crest of the ridje average frcn three to five feet ani overlay deposition cf residual naterial comprised ncstly cf nicacecus sand approtxi- niatcly ten feet in lepth. Dea^nposei granite is encountered at iepths -f f roH fi ftsen to twenty-five feet. Strippin- for the axKiliary It-^ alone this rid je should average about two feet in depth and the oxc-avatiun under the inpervious sections -f the fills should ewora^e ton fcut .eeper. The evcavated naterials, however, c on b c r ewoike d anl enbclied in tiio pervious portions cf the fills. One cf the proposed auxiliary Ions cuts acr: ss a deporession to neet the hills on the north rather tha n to neander up the Ion-- extension of the rid'^c. The bed cf this depression is obc ut 2^0 feet .vide and is fillci with deixjsits -f T;atcr T/om gravel, send, and silt. Strippin: across the bctton ahculd reach tro feet below the surf-.cc, anl doocnpcsed granite ShouLl be found -bcut twenty feet deeper, x.lcr.: the si les cf the dopraes- ion bed rock should be encountered at a nuch diallor/er depth. Under all lans a concrete cutoff vlcr. • the inpervicus portion cf the fill should extend bela; the excavation to scur.l :rjnite r int:. naterial that will safely resist underground percolation. 30 Materials frr Cccstructicn The necessary excavation in the bed of the Sar. Luis Rey Rivor nill provide sufficient s.:2id anl ;ravel cf suitable quality f c r ccncrote. Sufficient ::atcrial '.(-ith Aich tc a nstruct the inpervicus sec- tions cf the r.^iin eurth fill an^ the auxiliary structures vTas ftunl ibzut ^na- half nile upstrcon in the SEJ of the N^- ^i Suction 31 where the ores ion cf sr.iall chinnols tc depths cf ten tc fifteen feet has expcsei a dei", csit ^f rol claj'' alluviun vrhich is believel to be satisf actciy , The pervicus cLo -.tds treau portion cf the fill r.ay be nale frcn the excav'.t ions in the river bed end the spillv/ay channel and frcn the diffinto jrated jranitc cf the siorrounlin - hills. Dcu'ii and Reservoir It is pr?batle thit either an earth fill, reck fill cr c.ncreto Ian could bo built at this point. Hcvrever since there are no extensive cutcrcps cf reck close by which ■.. culd be suit±)le for a reck fill an ^ since a concrete structure would require extensive excavation i n be th atu tr.ei: t s , an e-arth fill type cf :". an has been desi3ned for this structure. Estirates have been m de cf the cc st s cf reservoirs with rollei earth fill duras with crests at elcvaticns 22- and 26^ feet above sea level. In m-3kin3 these estimates both :.ain dens were designed with an inpervious section wit h a cr.st wilth cf ten feet and slopes cf 2.5:1 upstrean and 1:1 iownstroon., faced with a concrete pavinj 12 inches thick, n.rnal to the sl^pe. The i^wn- strean pervious section was ^ivoi a crest width cf 40fect and a dcwnstroara slope of 2,5:1 to a point io feet bdow the crest vrhere it -.Tas f]attenel to 3:1. The inpervicus section was extended t. bed reck but the porvicus section onitl at the stripping line, A concrete cutoff 2.5 feet wile was placed at the upstrcan toe and uxtecded 15 feet below the line of excavation. The spillway consistod cf a concrete 0-_iee sccticn Tithcut -ates and -TiVr. crest 2: feet below the top cf tho Iji. It t;-ls i4: feet Icn; anl wcull lischar > .:. ,5.. cubic foct -or seccn.;, the crest fl.v.- .1" a or^ce-in-SEC -year flo:l, ^zith thu :7ator surface 5.5 foet belcv; thu crest f the i.Tiin .la... The channel ^asslr. • thrcu i. the .:a7 betTvccn tho left „tu1nent ani the :.ain i^n-s f hills T7as ccncrotc lined tl"Tci'3h ut. Durin.: the c nstructicn cf the : ai tho 3 trea.'i fl "./ -.tcuII bo by-pcssci thr-u^h a 2 ' tunnol unicr the left abut-.cnt. Tnis tunnel v.cuil to concrete lineJ". thr-ix;h:ut anl after c>- istructio:. wcull be plu",red at thij up^^er eni -m-l isci as -.i ccn.luit fcr the cutlet pipe* V.'atcr '•-■^ul". enter the pi'.;e through 2. circuliiT concrete tcwer "Jith -ate vdlvos c^ ntr.ll;'.^. fi\,:ia "-ite hi_u3e en the t^p of the tOTrer. The fl^T? through the cutlet pipe .tc uLl be ccntrollol by a neeile valve -^.t the .c-.7nstreaa aii uf the tunnel ani an ener -ency slilo jate ycull be placel i:-x.- liat ely balcw the tunnel ^.lu,.-. The auiiliary liis were uesi^nei sinilarly tc tho :aii: di:; exce .t that the total crest v.llths •,7crc only i^ feet. The valuation cf tho reservoir lan-s, all invrivte .■:iiership, which it wculi bo necessary to acquire hjs been base! on the 1,36 tax re lis .f 3in Diejc County. The assussel value s q re siil t. be Jo.ut fifty per cent .-f tho true value. In e sti :.iat i n j the cost f icquirin- these l3i.ls, however, a f i jure three ti xs the assessed vduativ^n h'.s been uso^. As previously statc.l cstiriitos f c^ st -;ere .T.ic f > r res^rv irs created by a-aiis T/ith crests at -^levati.ns ZZ lil 26. feet above sea level. Soiiwhat letailei cstiirmtes of tho c -pita 1 ani annual c;' st s f the tw ■ lars are jiven in Tables ani 1^ respectively. The layout or. 1 cr.- ss sectior.s cf tho rsxin la.": anl spillway for tlie lar:er reservoir are shewn en Plate VI "B^ns 11 Daia oa Sar. Luis Ray Biver. " r^ L_/-\ I (_ 41. Spillway~ Channel i Dep-thof lining 18" 22 S pillw ay crest Elev 240' ^luJ*^^'^ 100 Length in feet ISO 200 i5\P%^ 300 to -o CO 200 C 100 o > LU TYPICAL SECTION OF SPILLWAY Showing OGEE SECTION AND LINED CHANNEL 6500 BONSALL DAM ON SAN LUIS REY RIVER IN SAN DIEGO COUNTY 1936 PLATE 5 3000 Length in feet PROFILE OF OGEE SPILLWAY, MAIN AND AUXILIARY DAMS BONSALL DAM ON SAN LUIS REY RIVER SAN DIEGO COUNTY 1936 CCST C? BCNS.ILL RrJSSnVOIK Crost c-f Dai.i ElcViti^n - 22... feet Caiacity .f H^serv>.ir t, s^ illv.-ay ii. U.S.G.S. Daturi 49,17*:, icro-ffcet ^rest cf S.iir.7ay- Elevctioit 2„jfeet Capacity tf Spillwoy nc:i jLt cr Dxi - 1^^ feet ■.^,5ITAL CCST r ar.s ( ..iui n .ul Aur i 1 iary ) Sxcavciticn Saiil on I gravel Earth ani soft reck Strippir-3 Cut cf f tronch Fill Iripervicus Pervious^ excavation us a I bcrrcT.; Ccncrete f-icin- & cut >-i'f S";illv;ay Zxcavaticn Scft K ck Hari reck C.ncrete O^ee section LiniH;^ 295, 7o- cu. yls. at 63,70u cu. y s. at 36,00. cu. yls. at 3,0&L cu. yls. -.t 67i,2Cl cu. y".s. at 24:3, 7v J cu, yls. at IC. , C'O cu, y\ s. at ..5: 2. . .•■:. ^.35 13,02^ cu. yis. at 12. jC 226, 3C: cu. y'.s. at C.5; 114, 33o cu. yls. at 1 .7C S,2CJ cu, yl s, jX, 7.5 14,90.. cu. yls. at 12.,. •147 , 63,7-u 72, JCC 6, ICO 271, 7 DC 12,2.0 35, DjG 167,000 ",775,500 113,i-.0 7, , .jOO 69,000 17;,30C i-il,L< By Pass onl Outlets ixcavaticn Harl reck Scft reck Concrete Tunnel linin ; Tiinnel plu^^ Outlet tc'.ver Steel Pil.e 30" Gates incluain: tra^racks etc. ITeeile valve 30" Sliie Gate 2.5 ft. x 2.5 ft. 45, oco cu. yls. at 7.50 26, vjCO cu. yis. it 0,70 10,1.!0 cu. yls, at 20.00 , . S50 cu, yis. at 7.50 I 6v cu. yls, at 7,50 ( 140 cU. yis. at 25,00 1,1.. feet at 1.50 5 1 at 6,0o0. 1 at 3,.0v 313 ,500 2^ f Oc \j 2^3, 6^ J 7 , lo^ 50 J 3,500 2,^ Co 6, \J'\J-- sub-tct al 2, j61, Iw^ TABLE 9 (Continue!) 43 Ainini strati en anil Ermine erin 3 C-^ntin.^encifc s Inter '^st iuriiig c ons true ti 01: 10>t of sub tc tal 15^;J cf sub total 5% rate 13 mcnths 236,100 429,210 132,400 TOTAL C,\PIT.-L COST 3,753, 30 <. .iNNIIVL COST Interest Doi^reciat iv;n JuTicrtizaticn-sinkini furd O;:or::tion & main ten oi'.c e . TOT-JL AIJNU.\L COST 5' ;rer c ent ,ur annun 0,35 ;:er cait en da;?. ^nJy 40 year 5 ;er cent annual paynieints a. 15 ,;er cent cr -^riuun 1 37 , 90: 3,3J0 31,1J0 5,600 232,900 I T;iBii; 10 003T OF BONSiiLL FfflSEKVOIR Crest cf Don, El ovation 2 6: f oct U.S.G.S. Datun Crc^st ^f SpillT/ay, Elev^ti.n 2-iO feet Hr:!i:^.t cf D-3r., 14 feet Capicity of Reservoir tc s: illvray lip 162, 61C Gcro-f eet Ccpicity .^f Sri 11 '.jay 30,500 aocc iL-feot CAPITAL COST Earth and scf t re d£ Dcir.s .(:.n Son! ana i^ravel Main lara Aux. ian Strippin.^ Cut off trench Fill Inper virus PcrvicuG, Excavation usod C-;ncreto fader; on- cutcff SpillT.ay Sxcavat ion HltI r;ck Soft rock Concrete; 0336 secticn Lir tnj^ By Pass ani Out lots Excavation Scft rcck Hard re ck C'.ncreto Tunnel lininj Tunnel plu"!; Outlet tcwsr S^eel Steel :i-:e '.2" Gate valves i:.cl. trashracks, 42" needle vilvc 3.5 ft. X 3.5 ft. slilc -ite j Reservoir Land & in;:rcve^onts Relocaticn .f reals Clearinj lani sub-tctal 507,100 cu, y^ls. at 0.50 ^ 253,300 4J, .00 cu. yds. at 1.0'J 40,;':0 272,5: cu. yds. at 0,50 136, 3:0 99,100 cu. y'.s. at 2.00 193,2:: 5,50^. cu. yls. at 2.? ll,::i 1,347,60.' cu. y;.3. at 0.10 73:,:>J0 725,200 cu. yds. at 0,35 36,3:C 100,00. cu. yds, at C,35 35,030 33,5 J. cu. yds. \t :i2 , 43,0^0 cu» yis. at ..70 143,40^ cu. yis. at v.. 5 10,5-i_ cu. yds, at 7.0. 12, 1^^' cu, yds. at 12,:: i:2, :.: 1,^51, i.o 33, 6 -v 71,7, ■• 7y,., 145,2 329,50 J 26 , 3-: ^ 45,30. cu. cu. yis .at 0.7v. yds. at 7.5l 13 , :Xi w 313,500 10,13: , 950 ( 60 ( 2s: cu. cu. cu. cu. yis. at 2C . : y:.s, at 7.&. yis. at 7,50 Tl s . at 2? . : 2s-3,6jO 5,5J0 .i,2c: etc. 7 1 1 feet at 6,0^ at 7.500. at 5,6.0. 7,300 4,X0 7,50. 5, 6 :o 6:4,100 601,3:0 6 9,700 ni. at 36,000. ni. at 20, 000. acres at 20. 216, -00 ISO, 000 194,000 1 ,261,200 4 046,200 «& TABLE 10 (Ccntimtl) A in in is t ration in;' En ;in serin ~ IO5C of sub to t^jQ. 4>i,60C Jontin ;encie s 15^ r^f 3ub total 606, JOO Interest Iurir.3 Construction S^b rato 1.. m-nth i:eilcxil 253,200 IDIkL C..Pn:»L COST b,315,9>.J ANNU.iL COST Interest 5 por cent ;?or -ymun 265,300 Dc;r£;CiL:ti>.n 0.35 per ctnt ;cr annuri, (-n 'la-i only 12, XO .\i.iortizaticn - sinking fund -iO year 5 ;or ccjt anuuil i^ij'rjDnts 1-4,000 0-;eraticn anl rAinteacnce 0.15 -^t cont ;er ai-nvLi .5,X''0 TOT.vL .il^WJ.'i COST 33-, 6:0 » 46 CHkPTlT? V j:onss:iat2 d.a:." a; 2 iiestswdir The Moiiserato roservcir aitc is loc'ito: in Sccticra 21, 22, 26, 27, 28, 29, 3:, 31, 32, 33, 34 an: 35, T. C S. , R 2 •„. Gnl i:. S.ction3 5, 6, 7 '.mi C, T. 10 S., R 2 V7., S. 3. 3. & M. The dci sito is 1 cato': lii the N rth- •.7ost one-quarter of Ssction 6. A tL-p.::-r:i..iiic survoy ond niiip of the- Ian sito, shc.Ti in A-.cn.lix "B", has been nc ic at a seals of one inch cqur.ls cno hunircl fcot with -; c .^ntcur interval of five feet. gccl^.j-y A jeclo^ic stuly f the a.-a sitt. ttcs ...^ .o iurin.: thi3 i.;vesti.::'.tion. In the cciirse of this stuuy ^39 lineal fu..t .f tr:;nch 2»5 feet wide by ^ibout 5 f.jct deep, 4 test ,its 6 feet by 6 foot by ab ut 10 feet lecp, and ab. ut 27 surfc^co -;its nna benches fren 3 to 5 feet deep -.vcre ±i~', a six by six f - ot tunnel 14= foet Ion- w^.s du;: i n the ri.;ht abutri;nt; an.l thro.; -.veils t-taliii:; 270 feet in iepthv/ero drilled in the river bed. The Ire ti.. n.^ ef the various .vcrkin^s rare shown en the topo.:^raphic ra:; of the Ian site in .-i,,; jn'.ix "B". Prcfiles 3hj!7in' the classific^.ticn of the ir.tcri JLs oiccunterod r-.re alsc shnm en th is mp .. The Monsorate '■ i.; site is Iccito'". en the San Luis Rey River at a -_.oint where the river has cut i cc ripar atively narr.w ;-. r :e betv/eeii riorseratc anl Lancastar Mount.ains. Tw ■ c Jay ns 77hich ir^in th^- e ..st-arly slopes :f the- tv.'o nountains join the- river frcn tl-je Nrthcnl Scut!-, i -t :o li at cl y abc ve tho da-a site. The left abutirent is fomod by a hard -:rTinit'.3 ic.o risin-; abru;7tly fr...n the river bed '.vhich f.:rr.iS the n rthern spar f Lncastcr nountiin, Tho ri ^ht abutnent is forr^ied by a lo77cr rid ^e jut tin .ut to the 3>-utl-.eaat fr^r. Mcnserate Mountain. The ,3ranitcs in the ri:ht abutrisnt rii-e aro deeply •.•eathcrcl and extrer.ely variable in type.. There are a few utcicppin;3 ;f har,. :ranito but much cf Uio mterial is disiatoirutocl and bally fractured. It is probable that a fault runs down the canyen thrc ujh the dan site. The 47 river bed betTreen the tvro abutnents is a level sandy plain about 800 feet vri.de supporting a grovrt-h of grass and Cottonvroods along the bank of the narro\v surface chrjmel vjhich lies under the steep bluff of the left abutment. Excavation The left abutment dome vri.ll require only shallovr surface stripping under the dovm streajn portion of the dam. Under the upstream portion, hovrever, doming cracks vri.ll probably require the removal of considerable hard blocky material in the preparation of a foundation for the impervious section of the dam. The three v/ells drilled in the stream bed indicated that over 400 feet of this channel v^culd have to be excavated to depths of from 80 to 100 feet belov; the present surface. The explorations on the right abutment indicated that it v/ould be necessary to excavate about 8 feet of material under the upstream portion of the dam with a further depth of 20 feet for a oorev/all and that, to insure the v/ater tightness of this abutment, it vrould be advisable to cover a large area on its upstream face either vrith gunite or with an impervious clay blanket. Comparison of Ilon serate and Bonsall D am Sites The left abutment at Monserate vdll require about 5 feet of excava- tion v:hile that at Eonsall requires about 1 foot of stripping and 3 feet of excavation, a total of 4 feet. The river bed at Bonsall is about 500 feet vride and requires a majci- mum excavation of about 55 feet in depth over a vri.dth of 130 feet v^le the river bed at Ilonserate is about 800 feet vdde and vrill require a r.aximum ex- cavation of fron 80 to 100 feet in depth over a vridth of about 400 feet. The right abutment at Bonsall vrill require a total depth of 4 feet in excavation vrith a 15 foot corevreill v/hile the right abutment at Monserate vri.ll require not only an S foot excavation vrith a 20 foot coreimll but also a 4.-3 lit ; 4 gravel ; rf4 > & CJ fcj ■*» C tifl c o ^ rH .H .rl U) rH rH O C ti O -P 0) t. 0) j3 cs ri -rc i; c t^ Q t3 O C t> (U > -PWO;Ct:+' a > ei ^ c a • to tJ c U -n (.. W -c >-. a ti o CO Ci w t tJ ,0(;D > cd -p psts* c r-\ O C > ID c-H flj tH •H rH d O a a U O -ri t= pq to K K pq V: P? O f! W -P - 4J o m LTN O rH lO W HJ CI ^ V£> UD r~- o P,, O rH (fl E; U C a rH O O rH O 0) rH c u o o > a; rH c ■ H c; -P o C! t. rH > +3 r-^ -P 7d C8 -H T) H (D 4J Elev. 28 Sand and Clay Water gr Clay wit growing Very hai granite Hard grs Extra h>- .2 - Q HJ tH o o J- VD O r^ ir> v^ rH rH -3- J- ~ ^3- Pi