Santa Cruz County History - Disasters & Calamities

The History of Floods on the San Lorenzo River in the City of Santa Cruz
by Daniel McMahon

18 Floods on the San Lorenzo River in 10 Decades.

Aeriel Photo of 1955 Flood
From The Big Flood
by the California Disaster Office, 1956.

The downtown area of the City of Santa Cruz has been located in the floodplain of the San Lorenzo River since the 1860's. This has been made apparent to Santa Cruzans many times between 1862 and 1982, when the river has flooded or threatened to flood parts of the town. There were more than 18 incidents described as "floods" between 1862 and 1958, though these recorded floods have varied in severity from minor inconveniences to major disasters for the city. A table of the dates and levels of these floods is available, as is an article on flood control, and the bibliography of the sources for these articles.

Santa Cruz on Dec. 23, 1955, as the "Christmas Flood" of 1955 recedes. The Riverside Avenue bridge is in the upper right center, and Beach Hill is on the right. Note the sand island in the lower reach of the San Lorenzo River, removed during construction of the levees, 1958-59. Note also the trees lining the river channel, and the buildings on both banks where the levees are today.

Earliest Recorded History of Floods: Mission Santa Cruz, 1791-1799.

The San Lorenzo River was named by the Portola Expedition on Oct. 17, 1769, and was an important part of what made the future site of Santa Cruz attractive for the founding of a mission. The expedition of 1769 found the river to be two to three feet deep and "18 varas" or about 50 feet wide on that October day. The site was officially chosen for a mission in 1774, and the mission was established late in 1791. A temporary church and several other buildings were quickly built but, " was soon found that the new establishment was too near the river and had to be rebuilt on higher land." The cornerstone of a new church (the historically known mission chapel of 1793-1850's) was "laid on higher land" on Feb. 27, 1793. The exact site of that first, temporary church is unknown today, but to be threatened by the river, it must have been either close to the edge of Mission Hill, or below it. (An 1853 map of Santa Cruz shows the river channel almost striking the bluff, where North Pacific Ave. is today.)

But the Mission's troubles with the river did not end with relocation to higher ground in 1793. The new church and its outbuildings, such as the flour mill, were damaged by heavy rains in 1796, 1797 and 1799. But more importantly for this history, the lower lands between Mission Hill and Beach Hill, used by the mission for growing crops, were flooded by the river in early 1798. From the combination of rain and flood damage suffered by the mission in its first decade, Santa Cruz became known as a "hard luck" mission. 1

Possible floods, 1799-1852

The only record (that I have yet found) of floods on the San Lorenzo River from 1799 to 1862 is an article that appeared in the Pacific Sentinel on Dec. 23, 1871. This article states that,

A flood occurred in the year 1822, when the water covered all the lowlands and rose to a greater height than ever before. Had the country been settled then as now the disaster would have been very great. The next memorable flood occurred in 1832, the water not reaching the extreme heights of ten years before, but still covering the low lands to a great extent. In 1842, there occurred another great flood, not unlike that of '32. The pioneer settlers of California remember distinctly the flood of 1852, and it is not necessary to dwell upon the particulars. The last great flood occurred in the winter of 1862...The winter of 1872 is supposed to complete the circle again, premising that a flood will occur every ten years.

Ironically, it was later on the very day that this article appeared, Dec. 23, 1871, that another major flood struck Santa Cruz. Generally, every year that ends in a "2" has not brought a flood, but the early groping for some sensible pattern of the recurrence of such natural events is understandable, and can be seen as a progenitor of the later system of classifying floods as being 10-year, 50-year or 100-year events. The idea that flooding occurs on a completely predictable basis was not proven out over the next 120 years, and in the absence of any verifying sources, the exact dates and severity of floods between the 1790's and the 1860's must remain uncertain. But it is likely that noticeable floods occurred in Santa Cruz, before heavy development of the floodplain, and the 1871 article provides some evidence of this. (The 1852 and 1862 floods mentioned are found in other newspaper articles from 1862.)

Development of Santa Cruz onto the Floodplain, and the Flood of 1862.

Between 1791 and the 1840's, the Mission (and later Town of Santa Cruz) and the civil settlement at the Villa de Branciforte were located outside of the floodplain, on the tops of the bluffs to the west and east of the river. As the population of the area grew in the late Mexican and early American periods, buildings other than mills or farm structures began to be built in the space available between the bluffs. A visitor commented in 1841-42, "In the space which separates the Mission from the Villa de Branciforte are being built new houses, which in due time will no doubt make an important city."2 Elihu Anthony built the first brick structure below Mission Hill in 1849, hugging the base of the hill, right where North Pacific Ave. runs next to the town clock today.3

Gradually, more houses were built in the lower lands, and the business district shifted down onto the "flats" as well. The intersection of Water, Willow (Pacific) and Main (Front) Streets became the "lower plaza," and the Mission plaza the "upper." Symbolizing the shift of the town to its present center was the decision in 1866 to locate the new county courthouse on Cooper St. rather than on Mission Hill. (See the article, History of the Santa Cruz Courthouse by Margaret Souza.) As the center of town moved down onto the flats, it also moved entirely onto the floodplain of the San Lorenzo River.

The first serious flood to hit the growing town was in the winter of 1861-62, and it was a shock to residents, as bridges and mills upstream were destroyed, buildings built on the banks of the river within the city were washed out to sea (one barn allegedly went to sea in an upright position), and water ran against the base of Mission Hill and eroded 30 feet of it away.4 This flood was different from later floods in that more damage resulted from erosion, both at the north end of town and down at the "Cathcart Orchard" than from actual inundation. The water level was described later as being comparable with 1871, or about 16 feet, and thus the flooding of what we now call downtown was not that widespread. (Of course, neither was the downtown at that time, which was concentrated in a few blocks near the lower plaza.)

The river did not follow its present course to the north of town, and there was a curve in the channel that directed high water at the bank near the town's north edge, near the base of Mission Hill. After the 1862 flood, it was claimed that the river was "several hundred feet nearer to the town" than it had been before. While damage from inundation and moving water laden with debris were to characterize later floods, the flood of 1862 raised fears about the loss of land underneath the buildings, land which was valuable for expansion of the town.

Changes in the River's Course, 1850's to Present

Map of Santa Cruz, 1853
Map of Santa Cruz, 1996

The river's approximate course north of downtown in the 1850's and 1860's was much nearer to the base of Mission Hill. Most of the town of Santa Cruz from the early 1850's was concentrated near the Lower Plaza, very near to the bulkhead built after 1862. Information on the course of the river in the 1850's is taken from an 1853 map of Santa Cruz by A.D. Bache. River St. follows the old course of the channel closely where it rounds the north end of Mission Hill.

The response to this flood by townspeople was the earliest form of flood control: they built a bulkhead to stabilize the river bank near the plaza (at the site of today's Bulkhead St.), they began work to change the river channel so that it would run past Mission Hill and not straight at it, and property owners on the lower part of Willow (Pacific) began to fill their lots, in order to raise the grade and prevent the San Lorenzo from crossing through their land on the way to Neary's Lagoon. (The land on lower Pacific, and in other parts of downtown has been raised four feet or more from its natural grade by such filling.) One last feature of the flood of 1862 was that there were no bridges across the river yet, thus no bridges to be damaged or to trap debris and raise the water level behind them.

Repeated Flooding of Santa Cruz: 1871-1958

Subsequent floods, beginning in 1871, found bridges in the river channel, and damaged them or built logjams behind them. There were also more buildings near the river that could be flooded, although these were not right on the river's banks. Such things changed the perceptions of floods after 1862. But generally, all subsequent floods sent river water into the same areas. The water usually left the riverbanks in one of two places, either at the foot of Pacific Ave. on the west bank (at today's Laurel/Broadway St. bridge) or at the foot of Broadway on the east bank. Lower Pacific was frequently flooded (1862, 1878, 1881, 1890, 1895, 1907, 1911, 1940, 1941, 1955) with a few inches to a few feet of water. The Broadway/Barson Tract/Riverside/May St. area on the east bank flooded frequently as well, with one to three feet of water (1871, 1907, 1938, 1940, 1941, 1955). The area near Paradise Park (and the Powder Mill) would be cut off and flooded (1862, 1881, 1938, 1940, 1941, 1955) and the east bank near Branciforte Creek and now-gone Garfield St. (the site of San Lorenzo Park) would flood next (1878, 1889, 1907, 1911, 1940, 1941, 1955, 1982).

High water levels would often flood the basements of buildings on Pacific Ave. (1871, 1878, 1880, 1890, 1940, 1955) and if the water was especially high, it would run up Soquel Ave., and flow down Pacific Ave. from a few inches to a few feet deep (1878, 1890, 1955). This water could reach several blocks west of Pacific Ave., and combined with rain water unable to drain to the river, would reach the Chestnut/Center/Church St. area (1889, 1890, 1940, 1941, 1955).

The highest floodwaters also hit hard at the North Pacific or Bulkhead area, as anywhere from a foot of water (1871, 1880, 1890, 1907) to a large portion of the river's flow (1955) would take this route, in the late 19th century flowing "over the bulkhead." The upper River St. area near the tannery would also be flooded on occasion (1862, 1907, 1940, 1955) as would the low-lying Josephine St. and El Rio Mobile Home Park (1940, 1941, 1955, 1958).

Bridges across the river would be frequently damaged by floods (1871, 1881, 1890, 1931, 1938, 1940, 1941, 1955, 1982). Wooden bridges were more vulnerable than concrete ones, as damage to bridges was universal in the 19th century, and often limited to the surviving wooden footbridges at Cooper St. and Ocean St. in the early 20th century. But concrete bridges could suffer as well. The footings of the unfinished Highway One bridge and the Riverside Ave. bridge were damaged in 1955, and the older half of the Soquel Ave. bridge was undermined, collapsing two lanes in 1982.

One area which flooded repeatedly, and from which residents were often evacuated by boat, no longer exists. The newspapers of 1878, 1880, 1889 and 1890 refer to the "island" in the river, which had houses on it. This was not the sand island in the lower reaches of the river, but was further upstream, and was also referred to as the "Midway Plaissance" or just the Midway. This island was "a raised patch of ground in the marshy lowlands of the San Lorenzo River...To reach the island pedestrians had to cross by a foot bridge from the end of Cooper St."(5) This would today be approximately the location of the parking lot of Long's Drugs, the Galleria, or the UA Theaters on River St., and the island feature (like the sand island further down the river) disappeared with the redevelopment project that followed the 1955 flood.

The "Christmas Flood" of 1955.

The costliest, deadliest, and most well-known flood in the history of Santa Cruz was on Dec. 22, 1955. Much is written about this event in other places, and it is remembered well by many local people. The river moved well out of its banks on both sides, and flowed down Pacific Ave. at a depth of three to four feet. Water reached the steps of city hall on Center St., and was over eight feet deep in places on the east side of Front St. At the time, this was called a 100-year flood, but is generally called a 40-year flood today. (The same can be said for the storm of 1982.) But the water level was unquestionably higher in 1955 than in any other historic flood. Nine people were killed in Santa Cruz, two of these in their house on Garfield St. Water flow had reached the maximum possible at the Riverside Ave. bridge, and the river had begun to back up behind it as the flood peaked. Had this peak occurred at high tide, the level of water could have been higher, and the damage to Santa Cruz would have been even worse.

Map of Floodplain, and Area Flooded on Dec. 23, 1955

Map of 
Santa Cruz, Dec. 1955 Flood
Map (c) 1997. Daniel McMahon. Information on street locations, the extent of the floodplain and the 1955 flood are from maps created by the city's Department of Engineering, published in San Lorenzo River Flood, December 22, 1955, by the Flood Control Committee of the Santa Cruz Chamber of Commerce, 1956.

The San Lorenzo River Since 1958

Since April 1958, the river has only come close to topping the levees in the city a single time, on January 4, 1982. There was some flooding along Branciforte Creek that day, and the benchland below the County Government Center filled with water. When one half of the Soquel Ave. bridge was undermined and collapsed, it took a large part of the telephone lines to the eastside of Santa Cruz with it. The water level measured at the Water St. bridge in 1982 was 18 feet above sea level, which is second only to 1955's 20.8 feet. The measurement of flow at the Big Trees gauge in Felton was very close to that of 1955, and clearly greater than the large flood of 1940. And yet the levees held, if only by a thin margin, and there was not a recurrence of the widespread flooding that the City of Santa Cruz had seen so many times between 1862 and 1958.

Photo of Soquel Ave. Bridge, 1982
Soquel Ave. Bridge Jan. 5, 1982

[Photograph taken by Daniel McMahon on Jan. 5, 1982. It is taken from the top of the levee on the west bank of the river, downstream from the Soquel Ave. bridge. The water in the river had already receded from the day before.]

For more information on the history of floods, flood control, and current (1997) plans for the river, see:


(For more information on the sources for this article, see the bibliography.)

  1. Story of the Mission Santa Cruz, pp.68-78, pp.188-195. The 1853 map can be seen in Santa Cruz County Place Names between pages 79 and 80.
  2. Story of the Mission Santa Cruz, De Mofras, on p.359.
  3. This structure was replaced by the "Anthony Block" which was moved to extend Pacific Avenue in the late 1920's. SC Sentinel, 1927 and Parade of the Past, 24.
  4. Pacific Sentinel, Jan. 17, 1862, p.2, c.1. "The bluff above Mr. E. Anthony's which, from its formation kept the current of the stream from washing the bank next to the town, has been gradually falling in until now about thirty feet is gone." This was a major storm for all of California, and flooded the Capitol building in Sacramento.
  5. The Sidewalk Companion to Santa Cruz Architecture p. 195.

© 1997 Daniel McMahon. Reproduced by permission of the author.

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