Pulling a car out from the mud after the flood of 1938.

The devastating floods in 1938 made it painfully clear that Riverside County government did not have an adequate program of flood protection. In June of 1944, as war continued to be waged in Europe and the South Pacific, the Riverside County Board of Supervisors decided to wage a war against flooding. What delayed action on this front between 1938 and 1944 is not clear. Perhaps it was the preoccupation with the war itself. San Bernardino County, with the creation of its flood control district in 1939 provided a blueprint that served as a guide for our County. The process in Riverside County began in June 1944 with each Supervisor appointing three representatives to what became known as "the Committee of 15". They were tasked with deciding how to best approach this local war on flooding.

Later in 1944 at one of their meetings, A. C. Fulmor, the County Surveyor, presented a comprehensive and visionary report. In that report he made the following observations:

1. As a general law county "The power of the Board of Supervisors to do work of this kind (flood control) is pitifully inadequate."

2. The County focus is on protecting roads and public property, not private property.

3. Water conservation is an absolute necessity.

4. The Federal Flood Control Act of 1938 provides funding through the Corps of Engineers (COE) that the County should pursue. The COE, however, finds it difficult to work with those counties not having a flood control district.

5. A flood control district will provide the opportunity to collect data and guide future planning.

Standing on the Mission Boulevard Bridge reviewing project plans for the Santa Ana River Levees, Riverside, are representatives of the State Water Resources Control Board, U.S. Army Corps of Engineers and Metropolitan Water District and State Engineer Hyatt, County Supervisor Pittman and (far right), the District's first Chief Engineer, Max Bookman.

Mr. Bookman emphasized the District's water conservation responsibilities. He instituted a groundwater level monitoring program and took over the San Jacinto River Spreading Grounds from Fruitvale Mutual Water Company. Whereas groundwater recharge at this site had been quite informal, the District improved the facility to enhance recharge and to measure quantities spread. Mr. Bookman also began a data gathering system of rain and streamflow gaging stations, and started bank erosion control using apricot tree cuttings placed between wire fences along the San Jacinto River.

Pigeon Pass Dam above Moreno Valley was completed in December 1957 and continues to protect this now highly developed area.

1957 By 1957, staff growth prompted a move from the courthouse to 2,300 square feet of rental space in the Schacker Building, a block away at 9th and Orange Streets. Also in 1957, the District became the first public agency to set up an in-house division of photogrammetry to produce maps using aerial photography. The average cost for contracted work had been $1,000 per square mile (per map) excluding ground control. The new division was able to produce one square mile of mapping, including ground control, for $355.

Slope Paving on Bautista Creek, June 1961.

1960 The State Division of Highways, in constructing Highway 60 through Riverside, severed about 15 acres off the north end of Fairmount Park golf course which became surplus property. The District purchased the parcel, bounded by Highway 60, Market Street and the Santa Ana River levee, for a modest $28,000. Armed with this choice land parcel, the District proceeded to design, and put out to contract, a 10,500 square foot office building at its present location. Thus the District was to have the first home of its own.

1961 District workloads increased substantially between 1957 and 1961, requiring a staff increase from 14 in 1957 to 55 in 1961, and the newly completed office building was occupied in February 1961.

1962 Completed in 1962, the San Jacinto River levee project was designed and constructed with Corps of Engineers funds and consisted of five miles of levee along Bautista Creek and the San Jacinto River in Zone 4. The District provided funds for right of way, utility relocations and bridges. These local costs were reimbursed to the District by the state.

In 1962 the District began using electronic distance measuring (EDM) devices to speed survey measuring. This, the "Electrotape", was one such device.

The District began using electronic distance measuring (EDM) devices in 1962, significantly speeding up survey distance measuring. An EDM could accurately measure one mile or 20 miles in just minutes. With conventional transit and steel tape, a like survey line would take hours, and if the line of sight needed clearing of brush and trees, it could take days.

1963 The District maintenance force was originally headquartered on County Road Department property in San Jacinto and much of its work in the early years was along the San Jacinto River in Zone 4. In 1963, a 50' x 100' concrete "tilt-up" building was erected at District headquarters in Riverside and the maintenance function moved there.

On October 18, 1963, Orange County Water District filed a lawsuit against virtually all Santa Ana River Basin water users upstream of Prado Dam, except the San Jacinto River Basin tributary to Lake Elsinore.

Placing rock "revetment" on the San Jacinto River Levee during its construction by the Corps of Engineers in 1961.

Exercising its authority and water conservation responsibilities, the District provided legal and engineering representation for more than 200 public and private water users within its boundaries. Also, the District established and supervised the "water defense office" in Riverside. It was the distribution center and repository for water suit data on behalf of all upper Santa Ana River basin defendants.

Four and a half years later, in February 1968, upper basin interests filed a cross complaint against Orange County water users, and on April 17, 1969, the suit was settled by "physical solution" providing for an annual minimum Santa Ana River flow through Prado Dam in terms of quantity and quality.

The Water Defense Office closed on June 30, 1969, with 4,149 parties, defendant and cross defendant, having been named and served. Thus was concluded the most massive lawsuit in California water history, with the District having played a significant role in defense of its area water interests.

The District's first computer, an IBM 1620, was put into use in 1964.

1964 Historically, all calculations for surveys, design, hydrology, etc., were performed using slide rules and mechanical calculators such as the "Frieden". These calculations are quite labor intensive, slow and tedious. Some design problems require multiple trial computations to arrive at the optimum engineering solution. Hydrologic and survey computations likewise are complex and require inordinate amounts of time to complete.

Faced with increasing workloads, the District purchased its first full fledged computer, an IBM 1620, in November, 1964. It had 20,000 bytes of mass storage. All major calculations in engineering and surveying were quickly shifted to the new machine. A water surface profile calculation which previously took about one week to complete, could now be done in less than a day. Two years later, the District bought its second digital computer, trading in the 1620 on an IBM 1130. The 1130 was faster and had more storage (100,000 bytes of mass storage) and cost less. Extensive engineering software was developed by District staff to do hydraulic, hydrologic and structural computations utilizing the 1130.

The Tahchevah Dam in Palm Springs (light area between the hills and the houses) is an earth fill dam constructed by the Army Corps of Engineers in 1964. The Tahchevah Dam protects the northern and downtown areas of Palm Springs.

During the March 1938 flood event, major flooding from Tahchevah Creek occurred through downtown Palm Springs. In 1964, Tahchevah Dam was constructed to control flood waters originating from the steep mountainous watershed above the city (see picture, left). The project, built by the Corps of Engineers, at a cost of $1.2 million, was partially funded by the District and the State, and is maintained by the District.

November 1965 flood. Highway 111 in Palm Springs was cut in two places disrupting traffic for several days.

Whitewater River at Indian Avenue as it appeared on March 23, 1965. Indian Avenue was destroyed by flood waters cutting back from a sand and gravel pit on the downstream side. The closing of Indian Avenue for 30 days added to the isolation of Palm Springs.

1965 In November of 1965, Southern California experienced the most signifigant rainfall flooding since 1938. The first storm occured from November 13 - 19, followed by another storm November 21 - 26. Because of the ground saturation from the earlier storm, the second storm caused significant runoff in streams in Riverside County and especially in the desert areas of the district.

Cottonwood Creek overflowed Interstate 10 east of Highway 111 junction and all traffic was stopped for several hours. The lack of all-weather bridges and flooding of major roads resulted in the cities of Desert Hot Springs and Palm Springs being isolated for a period of time. Access to other communities in the Coachella Valley was severely impaired. Several lives were lost as a result of people trying to drive across streams at "dry"-weather crossings. Cars were swept away, some with passengers trapped inside. Most District facilities were put to their first real test. For the most part, they performed well. The floods of 1965 did demonstrate the need for major flood control improvements throughout the district.

1967 By 1957, the topographic (contour) maps, produced by photogrammetry, were in such demand by private engineers involved in new land development that it was necessary to expand the division to keep up with the demand. In addition, the District's planning, design and subdivision processing requirements for topographic maps were increasing, and other County departments likewise were making increased use of District topographic maps.

Initially recommended by the U. S. Public Health Service in 1951 and subsequently by the Santa Ana Regional Water Pollution Control Board and the State Department of Water Resources, the non-reclaimable industrial wastewater line from the upper Santa Ana Basin area to the Pacific Ocean was investigated, planned and preliminarily designed by the District in the late 1960's. The pipeline carries away saline mineral wastewaters which would otherwise diminish groundwater quality. Though ultimately built by other agencies, the project is essentially as envisioned and planned by the District and has facilitated significant industrial development upstream from Prado Dam.

At its construction in 1968, Wide Canyon Dam east of Desert Hot Springs was the largest District dam.

1968 Wide Canyon Dam, east of Desert Hot Springs, was constructed to control flood flows from a large drainage area prone to producing flash floods. At the time of its construction in 1968, it was the largest of the nine flood control dams built by the District.

1969 Two storm periods in January and February of 1969 produced flood peaks in the Santa Ana River at Riverside greater than any in the previous 31 years.

The 10-day storm period, January 19-29, produced more than 7 inches of rainfall in Riverside. This was noteworthy as the annual average rainfall for the previous 89 years was eleven inches. Storm total precipitation at Lake Arrowhead was 42 inches, with 29 inches in the form of rain.

Flooding of the Brockton Arcade area of Riverside in February 1969.

Cabazon was in shambles and several hundred of the town's residents were evacuated by helicoptor in some of the flooded sections.

Aftermath of the storm of February 1969 flooding on Temescal Creek in Corona, Magnolia Avenue and the Pacific Electric Railroad tracks. This problem was corrected by the construction of Temescal Creek Channel.

Churning floodwaters of the Santa Ana River resemble ocean waves as they attack the Market Street bridge in the city of Riverside.

The resulting peak flow at Riverside Narrows was 41,000 cubic feet per second on January 25th. Prado Dam experienced a peak in-flow of 77,000 cfs on January 29th. Above normal rainfall occurred throughout western Riverside County causing significant flood damage. The northbound lane fill section of Van Buren Boulevard Bridge over the Santa Ana River washed out on January 28th. The Mira Loma area and the Temescal Creek area in Corona each suffered some $2,000,000 (in 1969 dollars) in damages. Included was complete severance of East 6th Street and the washout of 1,300 feet of Pacific Electric railway track in Corona.

The President of the United States declared Riverside County, along with 35 other California counties, a disaster area on January 26th.

The six District dams around the south and east sides of Riverside stored the greatest amount of flood waters since their construction and City of Riverside flood damage was reduced by virtue of the storm volume controlled by the dams. Other District facilities - dams, levees, storm drains and channels generally performed well and prevented much potential damage.

Following nearly 9 inches of January rainfall in Riverside, and some $15,000,000 in flood damage in the County, repair work proceeded in most areas. The Van Buren Boulevard fill section was restored to traffic use by mid-February, as was the East 6th Street crossing of Temescal Creek in Corona. Between February 5th and 23rd, the Santa Ana watershed soils, still draining January storm moisture, received yet another 3.6 inches of rainfall at Riverside and more than 25 inches at Big Bear Lake, typical of the upstream, higher elevation areas. Then 5.72 inches fell in Riverside February 24th through 26th, bringing the rainfall total at Riverside, for January and February, to 18.19 inches.

February storm flows caused much more damage than those of January. Antecedent (January) rainfall had rendered watersheds saturated and surface materials loose. This scenario encouraged damaging flows for longer periods and resulted in increased debris volumes.

Both southerly concrete spans of the Van Buren Boulevard bridge over the Santa Ana River collapsed. The river also washed out part of the River Road (Auburndale) bridge downstream. Temescal Creek again severed East Sixth Street, Corona, as well as Hamner Avenue and River Road near Hamner. Other flood damage areas included Oak Street Channel, Corona; San Jacinto River, Lakeview; Salt Creek at Goetz Road; Little San Gorgonio Creek at the spreading basins, Vineland Street and Cherry Valley Boulevard; Noble Creek at Cherry Valley Boulevard, Beaumont Avenue and 14th Street; San Gorgonio River at South Cabazon; Tahquitz Creek at Sunrise Way, Palm Springs; and Murrieta Creek, Temecula

The January-February 1969 storms resulted in $40,000,00 (1969 dollars) in damage to public and private property in Riverside County. The County suffered greater damage than 32 of the 35 "disaster" counties in California.

1970 The citizens of Zone One, having been dramatically awakened to the power of flood waters during the 1969 storms, approved by a strong majority, a $30,000,000 bond issue for flood control improvements in November 1970. The bond issue was the first in District history.

1971 Armed with the bond funds and higher tax revenues, the District forged ahead with design of major Zone One projects. Combined bond monies and pay-as-you-go funding was projected to be $38,000,000 for a 15-year program. In order to expedite the design work, staff increased to 100 and was supplemented by contracting with private engineering firms for additional design capability. As a result, early construction of several large projects was accomplished and considerable cost saving was achieved through avoidance of higher than anticipated inflation rates in the later years of the program.

The substantial increase in engineering design load required additional office space, and that was achieved through a 5,500 square foot addition, plus some interior remodeling to better utilize existing space.

The HP3000 system with its periodic upgrades stood the test of time. For 16 years all the District's engineering, surveying, accounting and maintenance scheduling computing was performed using the HP3000. Currently, most of the engineering and surveying computing has migrated to personal computers.

1974 By 1974, District staff grew to 110, and the combination of bond funds in Zone One and increased tax rates in all zones pushed the budget to an all time high of $28,550,000.

Computing capability was enhanced with the 1130 computer system being replaced by a Hewlett Packard Model 3000 computer. Having 320,000 bytes of memory storage and capable of handling 16 users, simultaneously at separate work stations, this system with periodic upgrades, became the mainstay of the District's all around engineering computational tools.

Purchase of an orthophoto stereoplotter in 1974, enabled the District to become first in the nation, and the world, to produce a digital topographic map in a production environment. Now it was possible to produce a three-dimensional drawing, by computer, to show how a proposed project would look upon completion.

The benefit of District computer utilization is demonstrated by the estimated 100 man years of engineering time saved, a total worth of approximately $2 million, during the short period 1973 through 1977.

Arlington Channel was a major construction project for the District. It was in the planning stages for many years until construction funds became available through the passage of the 1970 bond issue. With its completion, development in southwest Riverside was able to proceed.

1975 The District, since its inception in 1946, was a principal collector of basic hydrologic data. In the early 1960's it was using automatic devices to continuously record rainfall and stream flow at specific sites. However, in July 1975 a telemetered flood warning system was begun. Thirteen remote stream flow gages utilized radio equipment (some solar powered) to report storm flow events to District headquarters. In addition, flow recorders began to be used in improved District flood control channels.

1976 Acquisition of a flatbed graphics plotter in 1976 completed the District's automated mapping process, completely eliminating hand-drawn ground contours, a tedious and expensive activity. Visitors from Europe, U.S. Geological Survey, CIA, Caltrans, State Department of Water Resources, and others came to view the automated mapping process. The District's photogrammetrist was called upon to give system presentations in Washington, D.C., Little Rock,San Francisco, New York and Ottawa, Canada.

1977 The total expended for District constructed projects through 1977 was $42,000,000, with Zone One Bond issue projects being 70% completed in only 40% of the programmed construction period. Therefore, major flood protection facilities were in place sooner than anticipated and at a savings in cost due to the reduced impact of inflation. Two of these major projects in Riverside were Arlington Channel Stage 1 and Magnolia Center Storm Drain Stages 2 and 3.

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Woodcrest Dam Spillway. In February 1978 the dam filled to capacity, overflowing the emergency spillway, the only such event to occur to any District dam to date.

1978 In the Spring of 1978, John W. Bryant retired after serving 25 years as District Chief Engineer. During his tenure, staff grew from 14 to 110, and design and construction was completed on 9 dams and countless miles of channels, levees and underground storm drains. The first District office building, on District owned land, was constructed. The non-reclaimable industrial waste line to the Pacific Ocean was envisioned, planned and preliminarily designed. His appearances before Congressional committees in Washington resulted in receipt of nearly $13 million in Federal funds to assist in financing projects within the District.

Later in 1978, Assistant Chief Engineer, Kenneth L. Edwards, was appointed Chief Engineer. He had joined the District in January 1962 as its Planning Engineer, coming from the Los Angeles District office of Corps of Engineers.

In June 1978, the voters of the State of California approved Proposition 13, which amended the State Constitution to, in part, limit the maximum ad valorem property tax to one percent of the value of real property, and future bonded indebtedness was severely limited. The passage of Proposition 13 had an immediate impact upon local government financing. By virtue of the formula distributing the one percent property tax collected, the District suffered a 60 percent reduction in projected property tax revenue for Fiscal Year 1978-79. At the same time, Riverside County and the District experienced a most phenomenal growth period beginning in 1978. Such fast growth, coupled with the revenue limitation, placed a significant strain on the District to provide adequate service to the public. In order to cope with the demands of growth the County, urged by the District, levied fees on new development for flood control and drainage purposes.

Flooding in the vicinity of State Street (Highway 74) and Ramona Expressway, February 21, 1980, as a result of the breach of the San Jacinto River Levee.

The storms of February/March 1978 caused extensive damage throughout the District. Flood damage occurred at Wildomar, Winchester, Corona, Murrieta, Cherry Valley, Lakeview-Nuevo, Calimesa, San Jacinto-Hemet, Palm Springs and Desert Hot Springs. The Oak Street Channel in Corona experienced flooding similarly to 1969. Also in February 1978, the District's Woodcrest Dam, south of Riverside, filled and overflowed the emergency spillway. The overflow was relatively small and caused no damage, but the reservoir spilling was the first and only such event to occur at a District dam to date. Alessandro Dam, southeast of Riverside, filled but did not spill in 1969. Total flood damages in 1978 exceeded $9 million.

1979 A 1977 wild fire burned a significant portion of the Oak Street Channel watershed in Corona, generating a massive amount of sediment and debris during the 1978 Winter storms. Congress then authorized funding for a debris basin at the upper end of Oak Street Channel, and the District completed its construction in 1979 in cooperation with the Soil Conservation Service, at a cost of $1.5 million.

1980 February 1980 rainfall (following excess rain in January) was record breaking in many County areas. Eleven stations with 50 or more years of record accumulated their highest February totals in history. Valley stations were approximately 360 to 430% of normal, mountains and foothills 400 to 510% of normal and deserts 590 to 820% of normal. The District had in place a substantial system of flood control facilities which were severely tested during the 1980 floods. The Palm Canyon Levee, constructed in the 1950's, experienced heavy flows for several days.

The Oak Street Channel Debris Basin was put to its first test in February 1980. The dam and basin were constructed in 1979.

The flows undermined the concrete face toe protection and floodwaters briefly breached the levee on February 21, 1980, but rapid District response with heavy equipment closed the breach and contained the flood flows within the stream. The Smoke Tree Estates development and other commercial and residential properties along East Palm Canyon Drive, were protected from potential catastrophic damages.

Also on February 21, 1980, a section of the San Jacinto River Levee immediately downstream of the junction with Bautista Creek Channel collapsed. An estimated flow of 25,000 cubic feet per second had undermined the rock toe revetment and coursed its way through a mobile home park and portions of the City of San Jacinto, with floodwaters several feet deep and causing extensive damage. Other than these two levee failures, the District's facilities performed well and prevented millions of dollars in damages. The City of Riverside saw none of the damages and flooding experienced in 1969, due to protection the completed 1970 bond issue projects and other projects had provided. However, the floods of 1980 also demonstrated a need for additional flood control and drainage improvements throughout the District, where the widespread flooding in western Riverside county accounted for at least ten deaths, and in excess of $70 million in property damage.

Monroe Flood Retention Basin (Don Derr Park), Riverside. Built in 1982, it is one of several such joint-use District basins. Dry most of the time, basins such as this provide excellent sports and recreation facilities.

1982 Because of the reduced funding from property taxes brought on by Proposition 13 the District placed an issue on the November 1982 ballot for the voters to consider a flood control benefit assessment to fund critically needed projects in all of the zones. Only the voters in Zone 6 approved the assessment which would generate annual revenues for construction of new facilities and would sunset after 15 years. Over the period an additional 25 million dollars would be raised which, when added to available tax revenues, would provide for significant flood control project improvements in the Palm Springs, Cathedral City and Desert Hot Springs areas.

Retention basins are designed to take the "peak" off flood flows, as opposed to dams which can store the design flood for later release. Such basins are dry most of the time and, therefore, may be put to other uses between storms.

Constructed in 1982, the Monroe Retention Basin, better known locally as Don Derr Park, is used by the citizens of Riverside as they enjoy the soccer and baseball fields on the basin's floor. Restrooms and electrical equipment are on high ground while backstops and bleachers, designed to "get wet" occasionally, occupy basin bottom sites. A similar well used facility, the Anza Retention Basin ( Don Lorenzi Park), is also located in Riverside.

The Zeiss C120 Analytical Stereoplotter was a step closer to a totally automatic topographic mapping process. It was driven by an onboard computer and corrected for distortions in the aerial camera and film. The C120 combined each photo pair into a stereoscopic image and correlated the image to ground survey points to produce a digital topographic map.

1983 The booming development growth during the 1980's required substantial staff increases. As a result, mobile office units were moved onsite to provide additional work space in 1983.

1984 In 1984 the District initiated a sophisticated flood warning system known as Automated Local Evaluation In Real Time (ALERT). It consisted of fifteen rain and stream gages on the San Jacinto River and Murrieta Creek watersheds, which reported the occurrence of rain or stream flow to the Hydrology Storm Center at the office. This enabled rapid response by District staff to unusual storm events.

The digital process continued to facilitate engineering computer programming and mapping. In 1984, the first analytical stereo plotter was acquired. Driven by a computer and storing mapping data in digital form it allowed subsequent drawing on a graphics plotter. Fast and highly accurate, it changed District mapping for the better.

1985 In 1985, the Army Corps of Engineers completed a Reconnaissance Study of a project to improve the Lake Elsinore Outlet Channel. The project would reduce lake flooding levels such as occurred in 1980 and eliminate flooding along the outlet channel from the Lake to Temescal Wash near Riverside Drive. It was estimated that the non-Federal share of the project costs would be in excess of 4 million dollars of which the State would reimburse 70 percent.

Seven Oaks Dam on the Santa Ana River above Redlands. A major feature of the $1.4 billion Santa Ana River Mainstem Project.

1986 The District staff proposed to the Board of Supervisors a plan for eleven critically needed projects around Lake Elsinore including the outlet channel. A plan to issue 8 million dollars in bonds secured by a benefit assessment on all properties draining into the lake and benefitting from the projects was proposed. Supplemental funding from tax revenues was also a part of the plan. The Board of Supervisors and the Lake Elsinore City Council approved the plan and the issue was placed before the Zone 3 voters in November 1986, and a strong majority approved the assessment and the issuance of the bonds. Two years later, the Army Corps of Engineers completed a Detailed Project Report for the Lake Elsinore Outlet Channel and Corps Headquarters in Washington, D.C. approved the project and provided funding to commence construction plans.

Also in 1986 Congress authorized $1.4 billion for the Santa Ana River Mainstem Project, which provided for the construction of Seven Oaks Dam on the river near Redlands, Mill Creek Levee near Redlands, Oak Street Channel in Corona, raising Prado Dam, and Orange County Channel improvements for Santiago Creek and the river from Imperial Highway to the Ocean.

In 1986, the City of Palm Springs was brought totally within the District by annexation of eleven square miles of territory previously within the Coachella Valley Water District's stormwater unit.

Introduced in 1986, the "total station" survey instrument automatically measured distances and angles and stored data, thus enabling a digital computer to economically produce maps, cross sections, profiles and land boundries on a graphic plotter.

Surveying took another giant leap forward with the introduction of the Total Station in 1986. It combined theodolite, distance measurer and mini digital computer in a single, compact instrument. It measured distances and angles plus computed positions and elevations, while also storing the data. This instrument enabled the totally automated connection of points to produce maps, cross sections, profiles and land boundaries, all at a new level of cost effectiveness.

1987 By 1987, the District was ready to take the next logical efficiency step, the integrating of engineering, drafting, surveying and mapping. Purchase of a Computer Aided Design and Drafting (CADD) system made that integration possible. Also arriving on the scene at this time was the personal computer (PC). The District's first use of the PC was automating the drawing of record of survey maps, which proved to be a major time and cost saver. The combination of the PC and CADD provided a most powerful tool, augmented by a broad array of commercial and District developed software to support computer aided design and drafting directly on computer screens rather than on paper.

It was now possible to extract topography and cross sections from three dimensional "digital terrain models" (DTM's), and lay out proposed designs superimposed on screen electronically. Complex hydrologic, hydraulic, structural, survey and earthwork quantity computations were done in seconds, and evaluation of alternatives was accomplished with ease. Designs were finalized "on screen" and drafted on computer driven plotters, rendering hand drafting virtually obsolete.

The Temescal Creek Channel improvement project through Corona was completed in January 1987 at a cost of $7.5 million. District funding was augmented by Caltrans and Corona redevelopment monies.

The District's GPS continuously operating reference station (CORS) at Lake Mathews is managed jointly by the District and the Southern California Earthquake Center. The station utilizes satellites orbiting 12,000 miles above the earth to establish its precise ground position both horizontally and vertically.

1988 Historically, surveying had been based on ground monuments as fixed control points. Earthquakes, crustal motion, loss of fixed monuments, and the inability to feasibly replace or adjust monuments, required major change in survey ground control. In 1988, the District, along with the Riverside County Surveyor and with the support of the National Geodetic Survey, adopted the Global Positioning System (GPS), developed by the U.S. military. The system uses satellites 12,000 miles above the earth, in establishing precise ground position both horizontally and vertically.

Greater survey accuracy was achieved at a fraction of the cost by previous conventional means. Subsequently, the District joined the University Navstar Consortium and the California Institute of Technology, to do a GPS survey over a 7,000 square mile area.

1990 1990 saw the District attain an all time high of 196 employees. The design and construction of a new, more adequate, office building began at this time, with completion occurring in May 1991. A portion of the new 33,000 square foot building was leased to the Riverside County Waste Resources Management District.

Also in 1990, to implement the goals of the National Pollutant Discharge Elimination System (NPDES), instituted in the 1987 Clean Water Act, the District began monitoring the quality of stormwater runoff, especially during the critical initial phase of runoff. Automatic gages and samplers were situated in channels and underground storm drains to record storm runoff, in an effort to detect significant water quality problems

Two new office buildings, totaling 60,000 square feet, were completed in May 1991 and February 1993, on the existing site purchased in 1960. Location is Market Street at the 60 Freeway, Riverside.

1991 Tahquitz Creek, historically a flood threat to Palm Springs, was initially studied by the U.S. Army Corps of Engineers in the 1970's.. The Corps proposed a dam 40 feet high with a 400-acre-foot debris basin, plus 3.5 miles of concrete channel. Local environmental concerns and Agua Caliente Indian cultural objections caused the Corps to abandon the project and prompted the District to develop a modified plan. The concept was one of a more natural channel, a much lower dam with about 100 acre-feet of debris storage, a two mile reach of grass lined channel used as golf course, as well as bicycle and equestrian trails. The final project phase was completed in May 1991 at a cost of $12.2 million, of which $1 million was expended on recovery and documentation of Indian cultural resources.

1992 The District began the development of a Geographic Information System (GIS). This will be a spatially referenced set of data that can be retrieved and analyzed through desktop computers. It will be used to inventory and research existing and proposed facilities relative to underlying land characteristics such as property lines, ownerships, soil types, rainfall rates and environmental traits. The District's GIS will feature high positional accuracy, orthophoto backgrounds and scanned as built engineering drawings.

Significant rainfall during the first half of January 1993 that saturated the watershed, followed by a very intense storm on January 16, resulted in devastating flooding along Murrieta Creek. Flood damages in the cities of Murrieta and Temecula approached $10 million, with considerable damage downstream at Camp Pendleton Marine Base in San Diego County.

1993 During the two week period beginning January 5, 1993 over ten inches of rain fell on western Riverside county, resulting in seven deaths and causing more that $10 million in public property damage. Murrieta Creek flowing at a record 25,000 cubic feet per second (cfs), overflowed its banks and flooded Old Town Temecula at depths up to 5 feet resulting in $6 to 7 million in property damage. On February 3rd, the President declared the County a disaster area.

Aside from Murrieta Creek flooding in Temecula, other facilities throughout the District performed as designed, and prevented many millions of dollars in potential flood damage.

By February 1993, the second building of our new office complex was completed, adding another 27,000 square feet. About 30% of the normal cost to build comparable office quarters was saved by utilizing concrete "tilt-up" construction on both buildings.

1994 After several years of construction plan preparation, including re-reviews of the project feasibility, the Corps started construction of the Lake Elsinore Outlet Channel in 1993, which included enlargement and improvement of the outlet channel from the lake to Riverside Drive, five new bridges across the channel, and a debris basin and channel in Wasson Canyon, a major tributary to the Lake Outlet Channel. The project was completed and dedicated at a ceremony in Lake Elsinore in October 1994.

This project limits the 100 year lake flood elevation to 1263.3, which is 5.7 feet less than the pre-project condition and frees up about 207 acres of land for valuable lake front development.

Oak Street Channel, Corona, had its first stage of improvement in 1958 and its final project completion, as part of the Federal Santa Ana River Mainstem project in June 1994 at a cost of $23 million, of which the Corps of Engineers contributed $13 million.

Micro-tunneling is a concept first developed in Europe and first utilized in the United States in the mid to late 1980's to tunnel under existing operating structures through soft ground (not hard rock) with fairly shallow cover.

Construction inside the Oak Street Channel culvert under the 91 freeway at Corona.

The Oak Street Channel project involved crossing the 91 Freeway without interrupting traffic and the Day Creek Channel crossed the Union Pacific Railroad near the railroad overcrossing of the 60 Freeway without interrupting rail traffic. The only option initially available for both of these projects was "jacking" a very large concrete structure under the freeway and railroad. "Jacking" is a term for pushing a structure through the ground, excavating soil just ahead of the structure as it is being pushed. Because of the enormous forces and unknowns in pushing such a large structure, the District investigated and decided that micro-tunneling was a viable option and allowed the contractors to bid that method of construction for the Oak Street Channel crossing of the 91 Freeway and the Day Creek crossing of the Union Pacific Railroad. Our projects were the fourth or fifth time this method of tunneling was used in the United States. Both projects were successfully completed using micro-tunneling.

1995 Having ably served the District for 34 years, and as its Chief Engineer for 17 years, Kenneth L. Edwards retired in December of 1995. Under his guidance the District experienced phenomenal growth in staff and projects completed. Beginning his tenure concurrently with passage of Proposition 13 presented a real challenge. The District suffered a 60 percent reduction in projected property tax revenue for Fiscal Year 1978-79. In spite of this funding limitation the rapid rate of development expanded the tax base, and a schedule of fees levied on private developers plus special assessments provided monies to construct about $230 million in flood control facilities, during his term as Chief Engineer.

The District's inventory of constructed projects now includes 191 miles of channels, 42 miles of levees, 185 miles of underground storm drains, 16 flood control dams, 24 flood retention basins, 5 debris basins, 289 miles of access roads, 207 miles of chain link fencing, all on more than 5000 acres of project right of way.

Sediment from undeveloped areas upstream flows through the high velocity portions of University Channel only to settle in areas where the velocity slows. Maintenance personnel remove material to maintain channel capacity.

Maintenance procedures have progressed over the years to the point where a sophisticated computer program triggers periodic inspections and routine maintenance. The program also records maintenance activity on each project and the nature of the work accomplished along with associated costs. Mechanized equipment has seen many advances and yet much hand work is still required in such activities as trash collection, fence installation and rodent control. Weed control is a critical element of the maintenance program and relies on the use of highly effective chemicals which are much less toxic than those used in the past and are environmentally safe. The newest alternative method for weed control is mowing the growth areas with track mounted mowers when spraying is not a viable option.

1996 Twenty-seven years after joining the District staff, David P. Zappe was appointed Chief Engineer in March 1996. David is a prime example of one "rising through the ranks". His engineering and managerial talents have taken him from new college graduate and Junior Civil Engineer in 1969 to Principal Engineer in 1985, Assistant Chief Engineer in 1992 and Chief Engineer in 1996. He welcomes the challenge to keep the District at the forefront of technology in its efforts to safeguard the lives and property of its citizens.

Salt Creek Channel was designed with gentle slopes and a soft bottom to accommodate its use as a golf course, while maintaining the capacity to carry a hundred-year flood.

Increasing concern over environmental impacts of major flood control projects has led to implementation of comprehensive watershed planning to include multiple use features. Future projects will emphasize flood plain preservation and management in lieu of structural improvements, where possible, and incorporate water conservation, water quality enhancement and recreational features

More and more the influence on the surrounding environment is considered in the construction of open channels. Where once construction and future maintenance costs were among the driving forces behind channel configuration and composition, today the District is faced with balancing the cost to the public with the short and long term effects of concrete channels. Many channels are now designed and constructed for more than the single purpose of safely conveying flood waters. Channels are seen by many as the last foothold of many wetland loving species of plants and animals. Thus, the District works closely with the California Department of Fish and Game, Regional Water Quality Control Boards, the U.S. Army Corps of Engineers and others in the identification and preservation of the area's natural resources.

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