SUMMARY OF ELEMENTS UNDER STUDY

How will flood waters be controlled gestions made by citizens at public along the Salt and Gila Rivers? How meetings or through correspondence will Central Project (CAP) with the two agencies. waters be stored for distribution in central Arizona? Solutions to these To date, the Bureau and Corps have terns will be evaluated using techni­ two critical water problems are being identified a number of structural and cal and environmental criteria. The sought by the Central Arizona Water nonstructural actions that singly or in systems that are determined to be Control Study (formerly known as the combination could provide for flood most acceptable will be studied at an Study of Alternatives for Salt-Gila control and CAP storage. These "ele­ increased !eve! of detail until a pre­ Flood Control and Regulation of CAP ments" were studied in Phase I of the ferred plan or plans can be recom­ Waters) . The U.S. Bbrnau- of Recla­ study and will be studied further in mended. Plans are combinations of mation, with assistance from the U.S. Phase II, along with additional ele systems with the addition of neces­ Army Corps of Engineers, is con­ ments that were added as a result of sary financial, institutional and oper­ ducting the study, with considerable public comment. ational arrangements. At each deci­ involvement of the public in helping sion point the public will be actively develop solutions to the problems. During Phase II, the elements will be involved. The following diagram Many of the ideas discussed in this combined into sys1ems that achieve shows the sequence of the planning summary are a direct result of sug- the goals of the study, and the sys- process.

Process Fo "PI •i g Plans For Flood Cont AP Storage ELEMENTS SYSTEMS PLANS PREFERRED -(Phase Ila) (Phase llb) (Phase Ill) Plans - - - The most technically feasible environmentally compatible, - The most acceptable The most acceptable and publicly acceptable elements will be combined systems will De studied in plans will be selected for CAP - into systems further detail as plans storage and flood control CENTRAL ARIZONA WATER CONTROL STUDY

Special Edition 1

SUITE 666, SECURITY CENTER 234 N. CENTRAL AVENUE PHOENIX, ARIZONA 85004 TELEPHONE (602) 271-0915 r·---·

1

·------·-·-·-·-·-·-·-~---·~! ••••••• LEVE ES UNDER STUDY I -----• CHANNEL CLEARING UNDER STUDY 1/ CHANNELIZATION UNDER STUDY 'tt.~~ j ;:I- ,-r,,~ NEW WADDELL SITE 7 ~~ ii: AGUA FRIA DAM SITE - if \ ,1/ "': ~ ------t>:: ,-~-...... ,:rl / CALDERWOOD t NEW ' t I .., •.,, BUTTE DAM~ RIVER DAM J I ~ I "'••AQUEDUCT (l.NDEA CONSl'RUCTIONI r ~

~HANDLER l) WILLIAMS A F 8- GJLA RIVER !NOIAN RESERVAl'lON I

COOLIDGE DAM­ (OFF THE MAP)

FLORENCE~./

0 COOLIDGE I q,GILA.8!!ND / I I I l __ i . . ~--. ---·-·-: ------·-·---·------·-·-·-·-·-·-·---·-· mTERSTATE 8 .\ !I !I Central Arizona ! I Water Control Study Areas !I I\ TAT MOMOLIKOT DAM . \

\\,_/,..-\\ ~/ J ! I ~------·--~-~~~------·- ---·- \ \ 2 3 ness in controlling flood waters . A systems, and finally plans will be con­ ical sites. Though further geological greater flood control. Construction of Project water storage facility, cannot Analyzing The preliminary cost-benefit analysis con­ structed. The elements range from studies are required, initial investi­ the dam could affect bald eagle and be easily modified, but a new and Elements stituted the economic evaluation proposed physical structures such gations indicate that enlargement of other wildlife habitats. Further study higher dam could be built down­ as and levees, to institutional Horseshoe Dam is feasible. is needed on the archaeological, so­ stream. The larger created cial, and historical impacts. Though would be used primarily for flood con­ Most of the eleme'lts have been stud­ During Phase 11, feasibility studies will measures such as water exchanges Recommendation: A further feasibility further geological studies are re­ trol with some water storage. Bald ied by the Bureau and the Corps in be performed for most of the remain­ and floodplain regulations. In various study is warranted. quired, preliminary investigations in­ eagle and other wildlife habitat could Phase I at an initial level of study. This ing elements Feasibility studies will ways, they provide for flood control dicate that this is a suitable dam site. be disturbed. The archaeological, level includes include: and/or CAP regulatory storage. Ide­ 1. More detailed analysis of water ally, an individual element would help Cliff Dam historical. and social impacts have solve both CAP regulatory storage Recommendation: A further feasibility not been fully assessed. Preliminary 1. Preliminary analysis of the ele­ supply or flood control capabil­ Cliff Dam would be constructed on and flood control problems. However, study is warranted. geological investigations indicate that ment's effectiveness for flood ities of the element the , immediately up­ most elements offer only partial so­ this is a SU1table dam site. control or supply of CAP water stream from Bartlett Reservoir. Cliff 2. Drilling program to determine lutions to these problems and must Dam would provide limited control of 2. Relationship between dam geological conditions below the be combined with other elements to Verde River flood flows but could be New Bartlett Dam Recommendation: A further feasibility height and reservoir capacity surface provide both storage capacity and combined with other elements for The existing Bartlett Dam, a study is warranted. flood control capability. 3. Literature review of geological 3 Site-specific engineering de­ information sign and cost estimates All of the elements that have been evaluated to date are described in the 4 Preliminary cost estimates 4. Studies of environmental, social, following sections of the brochure. A Salt River confluence of the Black and White neither flood control nor regulatory economic, demographic, and map showing the locations of all the Rivers near Alkali Canyon and east of storage needs. 5. Review by geologists and engi- other relevant non-engineering currently viable structural elements Sites to be considered for dam con­ Roosevelt Lake. The dam would im­ neers in the field factors may be found on page 2. At the end struction along the Salt River are pri­ pound flows of poor quality water Klondike Buttes Dam of the description of the elements. a marily suited for flood control, except thereby improving the quality of water Klondike Buttes Dam would be con­ Based on this initial level of study, Elements that have been recently table may be found that shows the for the sites at the confluence of the in downstream segments of the Salt structed on the Salt River just above some elements were recommended added at the suggestion of the public function of each element and the rec­ Salt and Verde Rivers and at Granite River. The dam would allow for the Roosevelt Lake, and its primary pur­ for further study, while other elements will receive initial study and, if war­ ommendations concerning further Reef. At this site, regulatory storage diversion of water to the to pose would be flood control of the were eliminated. The recommenda­ ranted, feasibility study. study. can also be provided. Additional auament the natural inflow to the San upper portion of the river It would not tions were based on three main fac­ water conservation may exist at other Carlos Reservoir. Carrizo Creek Dam be suitable for CAP storage. A dam tors: ( 1) geotechnical considerations, Your comments on any of the ele­ 1 sites through the use of water ex­ would be too far upstream to offer ef­ ' and reservoir at this site would impact (2) site location, and (3) economics. ments described or the issues dis­ changes between CAP and the Salt fective flood control for the Phoenix vegetation along the stream and Geotechnical considerations focused cussed may be added to the tear River Project. area, and it cannot be used for reg­ What Are The would encroach upon a proposed on foundation preparation, particu­ sheet at the back of the brochure. ulatory storage needs. larly the prevention of seepage at "Wild and Scenic Rivers" area. A dam Elements? This tear sheet can be detached and Carrizo Creek Dam the dam sites Sites were evaluated mailed. If you have no comments, you at this site would not control Tonto for their proximity to the CAP aque­ As the diagram of the planning pro­ may wish to return the card and have Carrizo Creek Dam would be con­ Recommendation: No further study is Creek, a major tributary to Roosevelt duct system or for their location in the cess shows on page 1, the elements your name added to the Central Ari­ structed on the Salt River below the warranted because the site meets watershed, and thus their effective- are the building blocks out of which zona Water Control Study mailing list.

deep under the dam site. At this time Verde River Verde River Area THEODORE no feasible method is known of effec­ ROOSEVELT The four elements that have been tively controlling these springs. Foun­ LAKE considered on the Verde River are dation material underlying the pro­ posed left abutment is unsuitable, dams that would be built primarily for IENLARGEDI flood control. These structures could and treatment is not economically FORT McDOWELL SALT RIVER INDIAN RESERVATION _/J _ r also be used for CAP storage through feasible. i1 ~ v'v ,, the use of water exchanges between APACHE LAKE the CAP and the Salt River Project. HORSESHOE DAM Recommendation: No further study is KLONDIKE BUTTES DAM SITE (RE CONSTRUCTED! warranted because of geotechnical SAGUARO LAKE problems. Tangle Creek Dam --COON BLUFF DAM SITE CARRIZO CREEK DAM SITE (OFF THE MAP) '------\\ . Tangle Creek Dam would be con­ __,,,. - structed on the Verde River seven Modified Horseshoe Dam "\ CONFLUENCE DAM SITE miles upstream from the present The existing Horseshoe Dam, a Salt ~ GRANITE REEF DAM SITE Horseshoe Reservoir. This dam River Project water storage facility, is would provide limited control over BARTLETT RESERVOIR located on the Verde River down­ ™';;;,v eJ\ Verde River flood flows, but greater stream of the Tangle Creek Dam site. flood control could be obtained in Enlarging the existing structure could Salt River Area combination with other elements. provide both flood control and water D '-, s Geological investigations, including storage. This modification of Horse­ BUCKHORN aerial photographs, indicate the site shoe Dam could adversely impact \ contains serious geotechnical prob­ bald eagle habitat (i.e., living and \ lems. Hot springs have been found nesting areas) as well as archaeolog- 4 5 Lake, thus leaving a large uncon­ nical problems have been found at the confluence of the Salt and Verde Agua Fria Dam trolled drainage area. the site. The foundation consists of Rivers, providing a large amount of Agua Fria Dam would be constructed highly permeable materials, and ef­ CAP storage capacity in addition to . New River, five and one-half miles downstream Recommendation: No further study is forts to reduce seepage ar·e not prac­ flood control. This dam would require Skunk Creek and Cave Creek Areas of the existing Waddell Dam where warranted because the site meets tical because of local topography. twice the length needed at the conflu­ the Granite Reef Aqueduct crosses neither flood control nor regulatory ence site, and similar environmental the Agua Fria River. This site, consid­ storage needs Recommendation: No further study is and social impacts would result from warranted because of the geotechni­ ered primarily for CAP storage, would its construction. In particular, the wild­ have a long, narrow basin limiting cal problems. life habitats and flowing stream rec­ Modified Roosevelt Dam storage capacity. Environmental im­ reation opportunities would be af­ The existing Roosevelt Dam, a Salt pacts are expected to be minimal, but fected. Portions of the surrounding several archaeological sites would be River Project multi-purpose water hy­ Confluence Site (Orme Dam) Indian reservations would be flooded. drogeneration and recreation facility, affected. Extensive foundation treat­ could be enlarged primarily for flood A dam built at the confluence of the ment would be necessary. Severe Salt and Verde Rivers would provide Recommendation: A further feasibility control, although increased storage study is warranted. seepage losses from the reservoir for CAP water is also possible. Dam CAP storage and flood control for area to the ground-water basin are height could be increased up to a both rivers. The reservoir created by likely, since no bedrock separation maximum of 20 additional feet without the dam would affect wildlife and Rio Salado Low Dams between the Agua Fria River and New requ1r1ng major design changes. bald eagle habitats, flowing stream Rrver has been found. Rio Salado Low Dams would consist Some archaeological sites would be recreation, archaeological and histor­ of three earthen structures on the Salt adversely affected by a larger reser­ ical sites, and would flood significant Recommendation: No further study is River between Mesa and Phoenix and voir Roosevelt Dam is on the National portions of the Fort McDowell and Salt warranted because of geotechnical CAVE BUTTES could provide minimal CAP storage. Register of Historic Places. This site River Indian Reservations. Smaller problems. DAM SITE These sites have serious geological has no identified geological problems. structures at this site will also be studied. Some adverse impacts problems and would require lining the Recommendation· A further feasibility could be reduced by construction of to prevent seepage. Sur­ face regulatory storage does not ap­ Calderwood Butte study is warranted. a smaller dam, but a loss in flood con­ SURPRISE pear to be feasible since these dams trol capacity wouid also result. It is Calderwood Butte Dam would be a themselves may require upstream possible for a smaller structure to be mile-long earthen dam constructed protection from flooding and si lting. Coon Bluff Dam used in combination with other ele­ about three miles downstream from No archaeological, environmental, ments to achieve flood protection. the Granite Reef Aqueduct on the Coon Bluff Dam would be con­ or historical impacts have been I.IJKE A F.B Agua Fria River. This site would be z structed on the Salt River one mile Recommendation: A further feasibility identified. ~ a: 0 primarily used for CAP storage. ~~~a:-> upstream from its confluence with the study is warranted. □ a: Pumping would be necessary to re­ ~~w Verde River. The site has been ana­ Recommendation- No further study < Cl) is Cl) UJ lyzed only for regulatory storage, but warranted because of geotechnical turn reservoir water to the aqueduct. a: Granite Reef Dam No serious environmental impacts flood control could be an alternative problems and because the sites n use if there were no technical con­ Granite Reef Dam would be con­ meet neither flood control nor regu­ have been identified, although sev­ straints. However, serious geotech- structed four miles downstream from latory storage needs. eral archaeological sites would be affected. The depth of bedrock would require extensive foundation prepa­ dams to store CAP water has been dams could also impact archaeolog­ ration, and the reservoir area would suggested, but the topographical ical sites New River and Phoenix City Streams Recommendation: A further feasibility require lining to prevent massive conditions at these sites would pre­ Agua Fria River, Project. Sites along the Agua Fria study is warranted. seepage losses. No significant flood clude the larger reservoirs. If con­ Recommendation: No further study is New River, Skunk River, New River, Skunk Creek, and control for the study area would be verted to regulatory storage, these warranted because of conflicting re­ Cave Creek were therefore evaluated provided. dams would lose their flood control quirements between regulatory stor­ Creek, and Cave primarily as regulatory storage sites. effectiveness. Conversion of the age and flood control. New Waddell Dam would be con­ Recommendation: No further study is Creek Lake Pleasant Storage structed on the Agua Fria River im­ warranted because of geotechnical mediately downstream from the exist­ problems. Hydrological studies indicate that Lake Pleasant is located on the Agua ing Waddell Dam which impounds Coolidge Dam flood flows from the Agua Fria River Fria River behind Waddell Dam. Lake Pleasant. The primary purpose Gila River and contribute only a small portion to the Enough vacant space is available be­ of this earthen dam and reservoir en ­ Santa Rosa Wash Coolidge Dam is located on the Gila total flood waters on the Gila River. hind the existing dam for CAP storage largement would be to provide addi­ North Phoenix Flood Control Dams River within the San Carlos Indian Therefore, Agua Fria sites have not during years when Agua Fria River tional space for CAP storage. The (for CAP) Reservation about 60 miles east of been analyzed for single-purpose runoff is low. A canal would be reservoir would be directly connected The proposed elements along these the town of Florence. Historically, San flood control. Since Granite Reef Aq­ needed to connect the CAP Granite to the Granite Reef Aqueduct by The Army Corps of Engineers is cur­ streams have received limited atten­ Carlos Reservoir behind Coolidge ueduct crosses these four drainage Reef Aqueduct with Lake Pleasant. means of a canal and pumping plant. rently constructing three dams: Cave tion. They were added to the study at Dam has rarely filled and space has channels close to existing and pro­ Waddell Dam was constructed in Geological investigations are cur­ Buttes Dam on Cave Creek, New the suggestion of the public and will been available. However, to use this posed flood control structures, the 1928 by the Maricopa County Munic­ rently under way to determine the River Dam on New River, and Adobe be evaluated for CAP storage. They space would require a sixty-mile construction of multi-purpose struc­ ipal Water Conservation District No. most feasible dam and spillway lo­ Dam on Skunk Creek. These dams have no potential for flood control in pipeline and a series of pumping tures has been analyzed. Planning 1. Since this dam is not a Bureau of cations and to determine if seepage will protect much of Phoenix from the Phoenix area. These elements, plants to connect the reservoir with and construction are currently under Reclamation structure, it would have from the reservoir is a problem. floods on these streams, but they will with the exception of Coolidge Dam the Salt-Gila Aqueduct. Construction way to provide flood control on New to be carefully analyzed to determine not offer flood protection on the Salt and Painted Rock Reservoir (see be­ of such a pipeline would be difficult, River, Skunk Creek, and Cave Creek if it would meet Reclamation criteria Recommendation: A further feasibility and Gi la Rivers. Neither will they pro­ low), will receive an initial level of and the costs would be prohibitive. by way of the Corps of Engineers' and standards for water storage. study is warranted. vide water storage. Enlarging these study. 6 7 thorized CAP feature to be located converted to regulatory storage, this seven miles upstream from the Flor­ dam would lose its flood control ef ence Dam site. A canal would be re­ fectiveness Environmental impacts quired to connect the Salt-Gila Aq­ are expected to be minimal since the ["] CASHION ueduct with Buttes Reservoir tor CAP Santa Rosa Wash Is dry HOLLY ACRES '{ \",\'1~{'. regulatory storage Impacts to min eral resources and wildlife habitat Recommendation More initial study ' D along the river could result. Some is warranted. ""~ C1 GUJ\DJ\LUPE water exchanges may be possible in connection with Suites Reservoir and Painted Rock Dam and Reservoir San Carlos Reservoir behind Coo­ lidge Dam. Painted Rock Dam and Reservoir are Wll.l IAMS A F B located on the Gila River near the GILA RIVEn INDIAN ReSERVATION Recommendation: More initial study town of Gila Bend. It has been pro­ is warranted. posed that flood waters stored in L 1 Painted Rock Reservoir be put to ben­ Tat Momolikot eficial uses in other parts of Arizona. COOLIDGE DAM __ Unfortunately, the Reservoir's down­ (OFF THE MAP) Tat Momolikot Dam is an existing stream location creates a problem in flood control structure located on delivering the water to the major ag­ Santa Rosa Wash on the Papago In­ ricultural and metropolitan area. dian Reservation CAP water storage could be provided by constructing a Recommendation: No further study is thirty-mile feeder canal from the Salt­ warranted because the site meets Gila Aqueduct to Tat Momolikot. How­ neither flood control nor regulatory ever, seepage of water out of the res­ storage needs in the Phoenix metro­ FLORENCE DAM SITE ervoir basin is a major concern. If politan area. D~ORENCE

PAINTED ROCK 0 COOLIDGE I ·------because of a lack of economic RESERVOIR Channels justification. (OFF THE MAP) 1 Channelization of portions of the Salt I and Gila Rivers has been proposed r.ASA GRANDE Levees f I to reduce flooding. Flows would be confined in relative deep, narrow Levees are embankments along a 0 l_._i channels constructed ·rn the riverbed. river that contain flows. They gener­ A Phase I cost-benefit analysis on ally provide a wider floodway than -~----·-·-·---: channelization showed that a contin­ channels and are constructed of INTERSTATE B ------~ uous system of channels between earthen materials. A continuous sys­ \ Granite Reef Dam and Gillespie Dam tem of flood control levees along the I is not justified. Specifically, the sec­ Salt and Gila Rivers has been ana­ tions between Granite Reef Dam and lyzed and found to be economically l Country Club Road and between 35th unjustified as a solution to the flood Gila River Area Avenue and Gillespie Dam do not in­ problem. However, further feasibility I cur enough flood damages to dem­ studies are warranted locally in two r onstrate a need for channels. The sections. the Salt River from Country section between Country Club Road Club Road to 35th Avenue and the T~OMOLIKO~"'DAJM \ and 35th Avenue does incur enough Gila River from the Salt-Gila conflu­ i damages to warrant further study of ence to Gillespie Dam. I I ,,.- \ \ I I "'~// channels. I \ /' ;/ l Recommendations: I \ - Recommendations: ----~~------~------·- \ 1 . Granite Reef Diversion Dam to 1. Granite Reef Diversion Dam to Country Club Road: No further Country Club Road. No further study is warranted because of Recommendation. No further study is and six miles east of the town of Flor­ dam and reservoir at the Florence site seepage losses from the storage study is warranted because of a lack of economic justification. warranted because this site meets ence. If Florence Dam were con­ would provide no downstream flood pool could occur. Additional geologi­ a lack of economic justification. neither flood control nor regulatory structed, the Ashurst-Hayden struc­ control on the Gila River. Environmen­ cal analysis is needed. storage needs. ture would be inundated, thus tal impacts along the river may be lim­ 2. Country Club Road to 35th 2. Country Club Road to 35th Av­ Avenue. A further feasibility backing up water to the proposed ited since the site is partially located Recommendation: More initial study Florence Dam Buttes Dam. CAP water would have on a dry wash. However, four prehis­ enue: A further feasibility study study for two-sided levees is is warranted. warranted. warranted Florence Dam would be constructed to be pumped from the Salt-Gila Aq­ toric sites would be affected. The ge­ is on the Gila River about four miles be­ ueduct to the reservoir for regulatory ology of the area is a problem and Buttes Dam 3. 35th Avenue to Gillespie Dam: 3. 35th Avenue to Salt-Gila River low Ashurst-Hayden Diversion Dam storage. As presently envisioned, a Buttes Dam and Reservoir is an au- No further study is warranted 8 9 . RESPONSE FORM

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a) Criteria used to eliminate several elements.

b) Potential impacts of remaining elements.

c) Other elements that should be considered.

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STREET CITY ------ORGANIZATIONAL AFFILIATION AREA OF INTEREST - Please Circle a. Biology g. Historical resources n. Rio Salado b. Geology/Soils h. Land use o. Agriculture c. Water Resources i. Recreation p. Wildlife d. Air quality j. Social q. Indians e. Acoustics I. Economic/Demographic r. Other (Specify) ___ f. Archaeology m. Public involvement Element Purpose Further Study Flood CAP Regulatory Warranted Unwarranted Reduction Storage Initial Feasibility • • • • ♦ LEVE ES UNDER STUDY LUKE A.F.8 VERDE RIVER --- CHANNEL CLEARING '-- UNDER STUDY (?=i SALT RIVER INDIAN RtSERVATIO~ Tangle Creek •-•-• CHANNEllZIITION UNDER STUDY • • • Modified Horseshoe • • • Cliff Site • • • New Bartlett • • • SALT RIVER Carrizo Creek • • Klondike Buttes • • RIO SALADO Modified Roosevelt LOW DAMS Coon Bluff • • • AREA ~HANDLER - • • Confluence • • • GILA RIVER INOIAN RESERVATION Granite Reef • • • Rio Salado Low Dams • • Confluence: No further study is AGUA FRIA RIVER AND TRIBUTARIES warranted because of a lack of Water Exchanges Operation of Salt economic justification. Lake Pleasant Water exchanges would involve River Project • • New Waddell 4. Salt-Gila Confluence to Gillespie agreements between the Bureau of (SRP) for Flood • • Dam: A further feasibility study Reclamation and responsible water Agua Fria Siphon is warranted for a single-sided agencies for the exchange of quan­ Control Calderwood Butte • • levee along the north side of the tities of CAP water for quantities of • • The Salt River Project (SRP) operates North Phoenix Flood Control Dams (for CAP) river. watershed-derived water controlled by these agencies. Three agencies under federal charter its system of • • with surface water sources and stor­ dams and reservoirs on the Salt and GILA RIVER AND SANTA ROSA WASH age reservoirs in central Arizona Verde Rivers, primarily for water stor­ Coolidge could be involved in water ex­ age and hydropower. The SRP Res­ • • Channel Clearing Florence changes: the Salt River Project on the ervoir system could be operated so • Salt and Verde Rivers, the San Carlos as to gain additional flood control. Buttes • The overgrowth of salt cedar and Project on the Gila River, and the Mar­ One or more of the following items .. • other such long-rooted vegetation Tat Momolikot • could be included in increasing has obstructed the river channel in icopa County Municipal Water Con­ • • servation District No. 1 on the Agua SRP's flood control capabilities: Painted Rock Reservoir parts of the Salt and Gila Rivers from Fria River (Lake Pleasant). • • 91st Avenue to Gillespie Dam. Clear­ 1. Sophisticated runoff forecasting CHANNELS ing a swath through this growth (channel clearing) has been sug­ The exchanges could be accom­ 2. Improved monitoring of water­ Granite Reef Diversion to Country Club Road plished as follows: • gested as a means to allow flood shed conditions Country Club Road to 35th Avenue • flows a path to follow. Several meth­ • 35th Avenue to Gillespie Dam • ods could be used to accomplish the 1. Vacant storage in a reservoir 3. Designated flood control space • clearing. would be made available for in existing reservoirs, which • CAP storage at the time this could vary according to season LEVEES storage is needed The Maricopa County Flood Control and watershed conditions Granite Reef Diversion to Country Club Road • District is presently investigating a Country Club Road to 35th Avenue • plan to provide a 1,000-foot-wide 2. The exchanging organization 4. Additional water outlets to the • • clear channel from 91 st Avenue to would agree to trade its water existing system. 35th Avenue to Salt-Gila Confluence • • Gillespie Dam. In addition, the Corps for an equal amount of CAP Salt-Gila Confluence to Gillespie Dam Use of these capabilities would de­ of Engineers has an authorized, but water • • crease downstream releases of water not funded, flood control project from the system, lessen flood dam­ CHANNEL CLEARING (1957 Survey for Flood Control, Gita • • 3. The exchanging organization ages, and increase utilization of the and Salt Rivers, Gillespie Dam to WATER EXCHANGE McDowell Dam Site, Arizona) which would later trade the exchanged Salt River floodplain. Impacts on flood • • water in partial satisfaction of its includes clearing the riverbed to cre­ control, water conservation, hydro­ SALT RIVER PROJECT CAP allotment or deliver on de­ ate a 2,000-foot floodway from Gilles­ power generation, recreation, and OPERATION AND FLOOD CONTROL • • mand the exchanged water to fish and wildlife habitat must be pie Dam to Granite Reef Dam. the CAP aqueduct system. evaluated. FLOODPLAIN MANAGEMENT • • Recommendation: A further feasibility Recommendation: A further feasibility Recommendation: A further feasibility GROUNDWATER RECHARGE • • • study is warranted. study is warranted. study is warranted. NO ACTION ,.- • 12 Floodplain 5. Bridge construction - con­ The type of information needed to struction of bridges of sufficient analyze groundwater recharge and Management capacity to pass flood flows, recovery in the study area is quite lim­ thereby reducing traffic delay ited. Also, conflicts over water own­ Measures costs during floods ership could arise unless provisions are made for such a scheme under Measures for flood plain protection Arizona's groundwater laws. include the following: Groundwater Recharge Recommendation: Further feasibility 1. Floodproofing - alteration of study is warranted. existing and future development Subsurface storaqe of water has by such means as floodwails, been suggested in connection with small levees, temporary clo­ both flood control and CAP regulatory No Action sures on openings, raised storage. Water could be controlled Alternative structures, and removal of upstream and infiltrated into the structures and/or their contents ground to raise the water table, thus The "no action·· alternative assumes storing surplus water for later use. In that none of the study elements would 2. Floodplain acquisition - pur­ order for this concept to be used for be implemented. However, any exist­ chase and removal of existing flood control, water must be taken out ing or presently authorized flood con­ structures from the floodplain of an aboveground reservoir during trol and related structures (i.e., dams, the winter season and placed under­ Indian Bend Wash, bridges) and the ground. This underground water stor­ 3. Floodplain regulation - use of CAP Aqueduct and Buttes Dam and age could be used in exchange for regulations to lessen flood Reservoir will be included in this ele­ space behind existing dams during damage ment. No additional water storage or the times of flooding. Pumping would federally funded flood protection fa­ be required to recover the ground­ cilities will be studied. Future devel­ 4. Flood warning techniques - water when it is needed. For CAP pur­ opment of the Salt River floodplain use of advance warning of im­ poses, proposals have been made would be limited under the "no ac­ pending flooding to evacuate that surplus River water be tion" alternative in accordance with people and damageable stored underground for recovery at a Federal Insurance Administration property later time. regulations.

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