Attempts to Dam and Close the Lower Mexican Heading

Background

The Lower Mexican Heading was a channel that was dredged between the Colorado River and the Imperial / Alamo Canal to maintain the water supply for farms in the Imperial Valley, CA, USA.  The channel was dug as an emergency measure to bypass a section of the canal that had become congested with silt and could no longer deliver sufficient water flow.  Due to a variety of reasons, the installation of a headgate to control the flow of the water was delayed.

The engineers that supervised the dredging were not deeply concerned about the lack of a headgate as they thought everything was completely manageable through other methods.  Several floods that occurred after construction was complete deposited large amounts of silt in the channel, reduced its size, and made it necessary to re-dredge the channel to maintain adequate water flow.  This served to reinforce and support their position that the situation was well in hand and easily controllable without headgates.

With no concerns about losing control of the river, all efforts were focused on keeping the channel open and maintaining the water supply for the Imperial Valley, but that changed after a much larger flood enlarged and deepened the channel.  From this point forward all efforts turned towards closing off the heading.

Over the course of the next two years, many attempts were made to dam and close off the Lower Mexican Heading, but time after time they failed.  For large periods of time during these years, the entire Colorado River flowed through the heading to the Imperial Valley and into the Salton Sea, leaving the original river channel to the Gulf of California / Sea of Cortez completely dry.

Confusion and the Purpose of the Information Presented Here

Every book, magazine, and newspaper that describes the various attempts to dam and close the Lower Mexican Heading categorizes and summarizes those efforts in a variety of fashions and applies numbering schemes which can easily confuse a reader with the differing accounts.  Additionally, some sources completely ignore various attempts, while others use different names, and some even seem to conflate the locations of the various attempts with the ‘attempts’ themselves.

The summary of attempts presented here carefully examines each source, including pictorial documentation, compares it with others, and and applies the most accurate numbering method to date.  Below is the definitive reference about the multiple attempts to dam and close the Lower Mexican Heading.

Summary of the Locations (Sites) and the Various Attempts to Dam and Close the Lower Mexican Heading
First Attempt

When; The first attempt to close the Lower Mexican Heading was started at the beginning of March 1905.

Where; The first location of the first attempt was just over [half a mile / under 1 kilometer] west of the mouth of the heading.  The mouth  of the heading was located on the west bank of the Colorado River about [4 miles / 6.5 kilometers] south of the California, USA / Mexican border.

Dimensions; The size of the heading was only slightly larger than the original ~[half a mile / one kilometer] length, ~[50 feet / 15 meters] width, and ~[8 feet / 2.5 meters] depth.

Who; Charles Robinson Rockwood directed the operation, with both men and women from the US, Mexico, and several Indian Tribes employed to do the work.

How;Two jetties were constructed from the north and south banks of the channel.  These jetties were made by tying together bundles of brush together in fascines that were placed with the bushy ends facing up stream to catch drift, dirt, silt, and other debris to fill in the gaps.  The fascines were sunk and held in place on the bed of the channel by sandbags.  This process was repeated and eventually the layers of fascines and sandbags were built up to a level that was above the surface of the water.  The fascines allowed water to flow through the structure without damaging it, otherwise, the swiftly moving current may have swept it away.  At this point, Fresno scrapers gathered and dragged dirt and silt out onto this structure to make it impermeable to water.  When completed, the jetties were about 20 feet wide, and extended out into the channel leaving a gap of about 30 feet between them.  A pile driver mounted on the dredge Alpha was used to drive two parallel lines of piles across the channel approximately [15 feet / 4.5 meters] apart with about three feet between the lines. A platform was then built on top of the plies where additional brush and sandbags were stacked.  Then they did what humans do very well, they blew it up.  Specifically, they destroyed the supports of the platform with dynamite which caused everything stacked on it to suddenly fall down into the water and block the channel.  The dam would have been completed by using the Fresno scrapers to move dirt and silt onto the structure to completely seal it.  These were tried and proven methods that were similar to other successful dams that were used to close the Upper Mexican Heading and Bypass Channel for the Chaffey Headgate in previous years.

Outcome; The attempt failed on March 30, 1905 as claimed by Mr. Rockwood when a large flood from the Colorado River destroyed the partially complete dam.  Another contributing factor to the dams failure was the soft silt bed it was constructed upon settled which caused the dam to sink.  There is a slight conflict as to the exact date because records indicate the floods peak was on Mar 20 and 21, 1905.

Water Flow Rate Through Lower Mexican Heading; 2000 cubic feet per second

Notes; It is worth noting that the equipment used in this attempt was limited to a steam powered pile driver, Fresno scrapers, a couple of steamers and barges, horses, and human effort.  There were no bulldozers, steam shovels, or any other large equipment used as the resources of the Colorado Development Company were very limited.

Sources, Information, & Issues;

  • The Imperial Press Saturday April 8, 1905 p. 6
  • The Imperial Press Saturday April 29, 1905 p. 6; Records kept a Yuma, AZ, USA clearly indicated the flood rising to its peak as it approached Mar 20 and then falling afterwards.  The flow rate of the river on March 30, 1905, the day Mr. Rockwood claimed the dam failed, was actually the lowest of the month.  These dates of these readings are very accurate, so it might be that the dam was eroded and broke up over a period of time rather than being swept away all at once.  Or Mr. Rockwood was out in the middle of nowhere and just lost track of the days..
  • The Salton Sea Menace by Edwin Duryea Jr. from Out West Magazine Vol XXIV, No 1 – Jan 1906 p. 14; A basic map is included on p. 15, but the numbering method disagrees with other sources that were directly involved with the work.
  •  Destructive Floods in the United States in 1905 by Edward Charles Murphy – 1906 p. 54; The author explicitly states the dimensions of the original Lower Mexican Heading, with no approximations, but makes no mention of the first attempts to dam and close the heading.
  • Statement of C R Rockwood – In the Matter of the Liability of the California Development Company for the Flooding of Salton Basin by Charles Rockwood – 1907 p. 20;  Mr. Rockwood deserves deference over the other sources as he was actually physically at the construction site of the dam.  The dimensions he states are not definitive measurements which is probably because the channel for the heading was not dug to exacting specifications and most likely varied in width and depth over its length.  No date is specifically given as to when construction was started, but March 1, 1905 is mentioned as a date where he made a decision about the construction, so it was probably shortly after this when construction actually started.
  • The Overflow of Colorado River into Salton Basin by James D Schuyler – 1907 p. 5, 6; Nothing is noted by the author on the subject of attempts, but water flow rates are mentioned.
  • The Possibilities of Salton Sea from Popular Science Monthly – Volume 70 by Charles Alma Byers – 1907 p. 13; The author of this story was a reporter that wasn’t directly involved with the work on the dam and wrote it almost two years after this attempt.  As a result, the story presents a broad picture of the events, but completely omits several attempts, with some details that disagree with other direct sources.  There are even pictures taken by Harry Thomas Cory, included as part of the Popular Science story, that have captions in his collection of pictures from Calisphere and UCLA (University of  California Los Angles), Library Special Collections, Charles E. Young Research Library that document the omitted events.
  • Irrigation in Imperial Valley California Its Problems and Possibilities by C. E. Tait – 1908 p. 46; This author mentions precise dimensions and even includes a measurement of a [1.5 foot / .5 meter] drop in altitude between the mouth of the heading and the location of this attempt that no other sources reference.
  • Born of the Desert – Imperial Valley in Its Making, not a Dream; A Brief History of the California Development Company by Charles Rockwood – from The Calexico Chronicle Second Annual Magazine Edition – May 1909 p. 24; This is another accounting of Mr. Rockwood’s memories of this attempt, so again deference must be given to him over other sources on what occurred, because he was actually there.
  • The Story of the First Decade in Imperial Valley, California by Edgar F. Howe and Wilbur Jay Hall – 1910 p. 102; This author puts a precise date of March 25, 1905 as the start of the first attempt which is much later than other implied start dates and conflicts with Mr. Rockwood’s explicitly stated date of March 30, 1905 as to when the structure failed, because there’s noway they could have made the progress made in just 5 days.   He also describes a levee made of mud and silt, but neglects to mention the piles or mattresses used in the construction of the dam, which given the importance of these items in the structure, is more than a mild oversight.
  • The Salton Sea – A Study of the Geography the Geology the Floristics and the Ecology of a Desert Basin by DT MacDougal – 1914 p. 19; This author breifly mentions the floods and the efforts to stop the flooding, but doesn’t include and specifics about attempts to close the heading.
  • The Imperial Valley and the Salton Sink by Harry Thomas Cory with Introductory Monograph by William Phipps Blake – 1915 p. 1265, 1286-1288, 1288-1290; A map in this book includes several diagrams and dates of the various attempts and locations, but doesn’t completely match up with other sources.  So although definitive days are given to certain events, it must be kept in mind that Mr. Cory was not there in person for this attempt and relied on information from other sources.  The map of the Chaffey Headgate area is also not accurate as it shows two headings dug from the river to the Chaffey headgate when there was only one.  What Mr. Cory labels as the ‘original’ intake didn’t exist until 1906 when the Hanlon Headgate was built and what is labeled as the 2nd intake is actually the original one.  He also neglects to include a diagram of the channel that was dug around the headgate, but does describe it in writing later.  This leads to several errors in his later references to intakes, headings, attempts, and locations.  Mr. Cory’s wording of the construction of the dam is also a bit confusing, especially when he references a ‘single line’ of piles, which is incorrect as a platform required two lines. He also includes Mr. Rockwood’s 1909 story in Calexico Magazine.
  • The Salton Sea – An Accounting of Harriman’s Fight with the Colorado River by George Kennan – 1917 p. 40; This book was written many years after this attempt was made and is a great story about the broad scope of events, but the author wasn’t there and based details on documentation from other sources, so it carries forward some of the same inaccuracies.  It also includes a copy of some sections of Mr. Rockwood’s 1909 story in Calexico Magazine.
  • The History of Imperial County California edited by Finnis C. Farr – 1918 p. 97-153; This book contains the complete story from Mr. Rockwood’s 1909 story in Calexico Magazine, but doesn’t directly document any of the attempts to dam and close the heading.
  • The First Thirty Years 1901 – 1931 – An Accounting of the Principal Events in the History of Imperial Valley, Southern California, U.S.A. by Otis B. Tout – 1931 p. 29-37, 100; This book includes a partial copy of Mr. Rockwood’s 1909 story in Calexico Magazine.  It also offers a description of the methods used to construction of the dam that seems to be based on information contained in Mr. Cory’s book that was published several years before this one.
  • Imperial Irrigation District – The First 40 Years by M. J. Dowd – 1956 p. 32; The author(s) of this story seem to reference Mr. Rockwood’s recollection of ‘under 60 feet’ and misrepresent it as exactly ’60 feet’.  Aside from that it just seems to repeat and summarize other sources.
2nd Attempt

When; The second attempt to close the Lower Mexican Heading was made at the end of March or beginning of April 1905, almost immediately after the first attempt failed.

Where; The second attempt was made at the same location as the first attempt, just over [half a mile / under 1 kilometer] west of the mouth of the heading.  The mouth  of the heading was located on the west bank of the Colorado River about [4 miles / 6.5 kilometers] south of the California, USA / Mexican border.

Dimensions; The size of the heading was not appreciably enlarged where any sources noted any size differences, leaving the the size of the heading close the original ~[half a mile / one kilometer] length, ~[50 feet / 15 meters] width, and ~[8 feet / 2.5 meters] depth.

Who; The crew, consisting of Charles Robinson Rockwood, men and women from the US, Mexico, and several Indian Tribes, were the same that made the first attempt.

How; The same methods that were used on the first attempt were employed on the second attempt.  See First Attempt, How, for a complete explanation.

Outcome; Before the dam was completed, a flood on April 15, 1905 destroyed the structure.

Water Flow Rate Through Lower Mexican Heading; 3000 cubic feet per second

Notes; No source gives a specific date as to the start of construction of the second attempt to close the Lower Mexican Heading and there is conflicting evidence as to the exact date the first attempt failed, so that is why a date range is given for the start date of the second attempt.  The date of April 15, 1905 seems to be accurate as Mr. Rockwood’s claim of this date is supported by the flow rates of the Colorado River measured at Yuma, AZ, USA which show the volume of the river peaking at this time.

Sources, Information, & Issues;

3rd Attempt (actually an aborted attempt, but an attempt none the less)

When; Construction on a larger dam started on May 29, 1905

Where; The third attempt to close the heading was made at a second location closer to the river in hopes of finding a firmer foundation to build upon.

Dimensions; The size of the heading was reported very accurately by a US Hydrographer employee to be to be [108 feet / 33 meters] wide and [15 feet 3 inches / 4.65 meters] deep

Who; C. N. Perry, an employee of the California Development Company, took over the direction of a crew similar to the first and second attempt which consisted of men and women from the US, Mexico, and several Indian Tribes with additional employees of the Southern Pacific Railroad.

How; Similar methods to the first two attempts were employed on the third attempt, but with larger piles and better equipment supplied by the Southern Pacific Railroad.  See First Attempt, How, for details of the construction method.

Outcome; The late start of construction and the arrival of the summer floods from the Colorado River caused Mr. Rockford to order construction be abandon on June 18, 1905, until after the floods had passed.

Water Flow Rate Through Lower Mexican Heading; 4000 cubic feet per second, which represented about 10% of the entire river flow.

Notes; The Southern Pacific Railroad (SPRR) made this attempt possible when just two days before they agreed to loan the California Development Company (CDC) $200,000.00.  Residence of the Imperial Valley were actually thankful for these flood events as it meant their water supply was secured, but they would soon learn that ‘security’ came with a steep price.  Work on the dam should have started earlier, but the CDC lacked the funds to mount any significant effort until the SPRR stepped in.

Sources, Information, & Issues;

Special Note; The map on p. 45 of the book Irrigation in Imperial Valley California Its Problems and Possibilities by C. E. Tait – 1908 is the most detailed and accurate map of the various attempts to dam and close the Lower Mexican Heading.  This image overlays Mr. Tait’s map onto a satellite image of the area as it exists today and the features match.

4th Attempt

When; The fourth attempt to dam and close the Lower Mexican Heading started on July 9, 1905, after the summer floods dissipated, and ended on July 30, 1905.

Where; The location of the fourth attempt was moved to a third location, this time in the Colorado River itself.  The mouth of the Lower Mexican Heading was immediately west of a small sand island that soon got the nickname ‘Disaster Island’ which split the Colorado River into two channels.  The location of this attempt was constructed in the western channel of the river between the tip of Disaster Island and the western bank of the river, [several thousand feet / about 1000 meters] upstream.

Dimensions; The size of the heading had increased to [about 300 feet / almost 100 meters].

Who; Mr. Rockwood along with a similar compliment of both men and women from the US, Mexico, and several Indian Tribes, plus the addition of some Southern Pacific Railroad Employees conducted the work.

How; Two jetties were constructed.  One started at the northern tip of the Disaster Island and moved diagonally across the channel to the western bank of the river.  The other jetty started on the western bank of the river, [several thousand feet / about 1000 meters] upstream, and was built towards the other jetty.  The thought was that the jetties would create ideal conditions for a natural sand bar to form, essentially causing the river to ‘self dam’ itself.  This endeavor was partially successful in creating such a sand bar as the jetties were extended out into the river.

Outcome; As the jetties extended towards each other and the gap between them narrowed, it caused the rate of water flow through the opening to increase to the point that it was impossible to further the construction, so the work was abandoned.

Water Flow Rate Through Lower Mexican Heading; 17,000 cubic feet representing about two thirds of the entire Colorado River flow.

Sources, Information, & Issues;

5th Attempt

When; Construction began on a new dam to divert water from the Lower Mexican Heading on October 13, 1905

Where; The dam was constructed in the channel of the Colorado River to the west of Disaster Island, between the tip of the island and the western shore of the river. This is the fourth location.

Dimensions; After the summer floods there were no additional events that served to expand the heading beyond its current 300 foot width.  But after the destruction of the Edinger Dam, the width doubled to about 600 feet.

Who; E. S. Edinger, an employee of the Southern Pacific Railroad was in charge of the staff that still consisted of men and women from the US, Mexico, and several Indian Tribes.  The Dam was named the Edinger Dam

How; The same method of construction on previous attempts was implemented on this attempt.  See the full explanation on attempt number 1.

Outcome; The dam was successfully completed but not able to withstand a very large flood at the end of November 1905.

Water Flow Rate Through Lower Mexican Heading; Upon the demise of the Edinger Dam, 100% of the Colorado River was flowing into the Imperal / Alamo Canal leaving the normal channel of the river to the south dry.  At the time of the failure, this represented a flow of over 100,000 cubic feet per second.

Notes; There are a wide range of dates given on the demise of the Edinger Dam from different sources, but newspaper reports indicate the water level of the Colorado River was at its peak on Nov 29 and then reported the failure the next day on the 30th.  It is possible that the dam was not ‘swept’ away in one feld swoop, but broke up, starting on the 29th and then gone on the 30th.

Sources, Information, & Issues;

Attempt 5.5 (Interlude)

On page 1302, Mr. Cory in his book, The Imperial Valley and the Salton Sink mentions that the dredge Alpha was sent to a location far to the west in an attempt to redirect some of the flood water in the Imperial / Alamo Canal to the Gulf of California / Sea of Cortez.  This accounting is corroborated in the book Destructive Floods in the United States in 1905 by Edward Charles Murphy – 1906 on p. 54 and 55.  Both accounts declare this ‘side attempt‘ a failure.

6th Attempt;

When; Preparation for the sixth attempt began during the summer of 1906 and the first material to arrive at the site was on Aug 15, 1906.

Where; The dam was constructed in the Lower Mexican Heading a hundred or so feet from the river and west of Disaster Island and although really close to the first two attempt locations, it was slightly west so it became the 5th location were an attempt was made to close the heading.

Dimensions; During the winter, spring, and summer floods, the heading had widened to about [half a mile / a kilometer]

Who; Mr. Hind was in charge of the usual crew of men and women from the US, Mexico, and several Indian Tribes along with a large number of Southern Pacific Railroad employees.

How; Sheer brute force was brought to bear on the damming the heading because the previous efforts of constructing a dam made of piles and brush demonstrated it simply wasn’t possibly to withstand major flood events.  A railroad track was laid starting in Yuma, Arizona, USA, crossed into Mexico and ran parallel with the Colorado River for about [4 miles  / 6.5 kilometers] to the the heading.  Jetties were constructed out from the north and south of the heading on sandbars that had been exposed after the summer floods to narrow the opening a bit.  A trestle bridge was then constructed across the remaining width of the heading making it possible for large side dumping railroad cars known as battleships to dump huge chunks of rock into the water.  Because of concerns that the large aggregate would sink into the soft silt bed of the heading, brush mattresses were constructed and placed on the bed of the channel and held in place by the pilings of the trestle bridge.  Over the course of several weeks, thousands of railroad car loads of rock were dumped into the water from the trestle bridge.  Eventually it was built up to a level above the waters surface and silt, clay, mud, and smaller aggregate were used to seal off all of the gaps in the structure.

Outcome; The dam was completed at the beginning of October 1906, but the Rockwood Headgate that had been built to the north of the dam to deliver water to the Imperial Valley failed on October 11, 1906 allowing the entire river to once again flow into the canal system and on to the Imperial Valley and Salton Sea.  The Hind Dam itself was fully intact, and the river had essentially bypassed the dam through the channel the headgate had been in.

Water Flow Rate Through Lower Mexican Heading; 12,000 cubic feet per second while the Rockwood Headgate was in place, surging up slightly and then falling to under 10,000 cubic feet per second over the next week or so.

Sources, Information, & Issues;

7th Attempt

When; Almost immediately after the failure of the Rockwood Headgate on Oct 11, 1906 construction began on extending the Hind Dam to the north, which was the 7th attempt to stop the uncontrolled flooding.

Where; The location was immediately north of the Hind Dam, and was the 6th location of the construction work.

Dimensions; Because of lower water flow, the channel that the Rockwood Headgate was in was not enlarged beyond 200 feet and eventually completely closed off.

Who; Thomas Hind continued supervision of the work with the same mix of men and women from the US, Mexico, and several Indian Tribes plus the Southern Pacific Railroad employees.

How; The same methods used on the 6th attempt were used with a couple of exceptions.  The water level downstream of the new breach exposed the bottom of the Hind Dam and it could be seen that it was unnecessary to use brush mattresses to keep the large rocks from sinking into the silt, so this step was eliminated.  Additional railway sections and train trestle bridges were built to speed the delivery of material.

Outcome; The efforts were successful and on November 4, 1906, all of the water that had been flowing uncontrolled into the canal system was turned into the Colorado River’s original channel that lead to the Gulf of California / Sea of Cortez

Water Flow Rate Through Lower Mexican Heading; 0 / Nothing.

Sources, Information, & Issues;

8th Attempt

When; December 5, 1905 saw a large flood destroy the levee to the south of the Hind Dam allowing flood waters to once again race through the canal system and onto the Imperial Valley and Salton Sink.

Where; This was the 7th location and was situated to the south of the Hind Dam.

Dimensions; The levee was compromised in several locations and during construction of the new dam several floods occurred which caused the width of the breech to vary on some occasions reaching several hundred feet.

Who; Thomas Hind was assigned to work on levees further downstream leaving Mr. Clark in charge of the usual mix of men and women from the US, Mexico, and several Indian Tribes plus the Southern Pacific Railroad employees.

How; The same methods used on the sixth and seventh attempts were used on this attempt, although slightly longer pile, some as large as 90 feet had to be used because of the depth of the channel.

Outcome; On February 10, 1905 the Clarke Dam was completed.  The efforts were finally successful making this the last and successful attempt to dam and close the Lower Mexican Heading.

Water Flow Rate Through Lower Mexican Heading; After the flood that destroyed the levee, water flow fell to about 12,000 cubic feet per second, but rose to almost 50,000 cubic feet by the end of the month.  During January it fluctuated from a low of 17,000 cubic feet to a high of 44,000 cubic feet.  And of course with the successful closing of the heading, water flow through the channel fell to zero.

Sources, Information, & Issues

The below map does an excellent job of showing all the major components of the Imperial / Alamo Canal and the work done to dam and close the Lower Mexican Heading.

 

Life of the Salton Sea