approved by the office and field inspections made of those under construction:

The law requires that the plans and specifications for bridges over navigable streams be approved by the State Engineer or Chief of Division. None have been presented for approval during the past two

years.

RECTIFICATION OF RIVER CHANNELS.

Construction of Current Retards at Jacinto and Arnold Bends.

A new type of bank revetment was introduced into California with the construction of current retards to protect the caving banks of the Sacramento River at Jacinto and Arnold Bends. This type of protection has been successfully used on the Missouri River to protect dangerously caving banks with a great saving in costs over types previously used there. The retards consist of a windrow of trees built outward from the bank and with their trunks parallel to the bank. The butt ends of these trees are placed upstream and fastened to cables which bind the windrow together and lead upstream to concrete piles jetted down with their tops below the stream bed. These cables hold the windrow in place against the impinging current. Extending out into the stream, these windrows make an effective retard to the current near the bank. Their partial permeability to the flow of the stream tends to relieve the formation of eddies on the downstream side of these retards and make them effective in causing sedimentation. These retards are placed at intervals along the bank to conform to the configuration of the stream channel.

Three retards were constructed during 1922 in the sharp bend of the river near Jacinto. The cost of this construction was shared equally by Reclamation District No. 2047, Levee District No. 1, and the state. Four retards were also constructed during 1922 at Arnold Bend near Colusa. The cost of this work was shared equally by Reclamation District No. 2047 and the state.

Clearing Channel of Sacramento River-Colusa to Chico.

The below-normal run-off in the Sacramento River of several of the recent seasons and the great increase in diversions for irrigation during the spring and summer months have made conditions favorable for the

growth of willows in the bottom and sides of the river channel. From Colusa to Chico, a distance of 51 miles, 425 acres of willows were cut during the summer and fall of 1922. These willows were growing rapidly on the leeward side of bends and on new forming bars, to become dense thickets obstructing the flood channel. The deposit of sand and gravel amongst these bushes by the retarding of the flood current in passing over and through them has been building new bars and enlarging old ones, all to cause further attack by the eroding current upon the river banks on the opposite side of the channel to the building bars. Many of the young willows grubbed out in this work were planted again in advantageous locations to protect exposed banks and by their growth and assistance in causing deposition of detritus, to aid in rectifying the river channel. All together about twelve acres of willows were planted.

Reclamation District No. 1500.

Racetrack and Ministerial bends, about thirty miles upstream from Knights Landing on the Sacramento River, have suffered heavily from the attacks of the river current. Reclamation District No. 1500 has spent large sums in preventing the undermining of their levee in these bends. A project for digging cut-off channels through these bends has been before the State Reclamation Board, but no program for construction has yet been arranged.

To hold the river from breaking through into the highly developed area behind the levee, additional protection had to be placed in these bends. Sixteen hundred feet of brush mattress, sixty feet wide, was placed, together with repairs to old revetment and isolated mats, with a total length of 3000 feet. This work was done in the fall and early winter of 1922. Twenty-three hundred dollars was spent on this work. The state paid one-third and furnished equipment and a superintendent.

Edinger-Johnson Levee.

The bend in the Sacramento River at the Edinger-Johnson place near Hood has been point of severe attack by the waves and river current for the past several years.

By December, 1921, the banks had caved in several places, so that the levee was materially weakened. Great property values depend upon the protection of this levee in the reclaimed land back from the river. A break in the levee in a time of flood would not only cause serious damage to these properties, but would impair the navigable channel of the Sacramento River.

The caving of the banks at this point is caused by the waves and current washing away the sand which lays below the thick strata of sediment composing the river bank. As the sand washes out from beneath the sediment, the overlying hard bank caves off in chunks to be later broken up and washed away by the waves and river current. In 1919 bricks were dumped in front of the bank at the points of most serious erosion, but this did not prove sufficient for the protection of the bend. Following December, 1921, 1800 cubic yards of broken rock were spread in front of the bank to prevent the waves and current from further attack on the low-lying sand strata.

Rough and Ready Island.

Concrete revetment on Rough and Ready Island having a total length of 3000 feet and a width of 14 feet was completed in September, 1921. This revetment protects portions of the levee along the navigable channel leading to Stockton, from the wash of waves occasioned by steamer traffic on this channel. The property owners paid half the cost of this work. The state paid the other half, and furnished equipment and superintendence.

Reclamation District No. 17 on San Joaquin River.

Work was started in July, 1920, on the front of Reclamation District No. 17 near the mouth of Walthall Slough on the San Joaquin River. The protection was completed in September, 1921. The slopes of the levee were paved with three inches thickness of concrete and a brush mattress thirty feet wide was extended into the river from the toe of the concrete revetment at the low water line. About 900 lineal feet of bank was so protected. The cost was $16,698.98 and was paid for by the property interests. The state furnished its equipment and superintend

ence.

Lower Sherman Island.

Protection work started in July, 1920, to prevent wave action on the lower Sacramento and San Joaquin rivers from washing down the levees on Lower Sherman Island, was completed in the spring of 1921. This work consisted of the brush fence three feet wide and five feet high, held in place with stakes on six foot centers. It was undertaken on the request of the State Board of Control, who had recently purchased the property for a spoil area to the dredging operations now in progress for opening up the mouth of the Sacramento River. These dredging operations are a part of the flood control project of the Sacramento Valley.

Mad River.

Twelve hundred lineal feet of brush and rock revetment was placed on the bank of Mad River in Humboldt County during July and August, 1920.

INTENSIVE ENGINEERING STUDIES.

Water Resources of Kern River.

Bulletin No. 9, "Water Resources of Kern River and Adjacent Streams and Their Utilization," of the Department of Engineering, was published after completing a field investigation which beginning in December, 1919, continued through the year 1921. These investigations were undertaken at the request of local interests and consisted principally of the study of surface storage possibilities and of ground water supply and its utilization. Conclusion was reached that a reasonably well-maintained supply was available from both sources to irrigate about 300,000 acres, and recommendations were made for the establishment of boundaries for a water storage distret. A complete description of the work and the results is given in the bulletin. The work was per

formed with Harry Barnes in the field, under the supervision of S. T. Harding. The cost of the work was paid for as follows:

An investigation of the water resources of Tulare County was commenced in 1920 at the request of Tulare County Water Users' Association. Available data on stream flows, storage sites and underground water was assembled and field work conducted to obtain supplementary data. The principal field work was directed toward the study of ground water conditions. Fluctuations of wells were observed, estimates made of the draft on the ground water and compared to the natural replenishment of these underground basins. Surface storage sites were also investigated and several surveys made.

The results of this work are now being printed in Bulletin No. 4 of the Department of Public Works, entitled "Water Resources of Tulare County and their Utilization," which gives a full account of the work.

The field work for this report was handled by G. H. Russell and Chester Marliave, under the direction of S. T. Harding. The cost of the work was paid as follows:

Tulare County Water Users' Association_
Tulare County

Division of Engineering and Irrigation_.

Water Resources of San Jacinto Valley-Riverside County.

$1,500 00

5,000 00

6,600 00

San Jacinto Valley, lying in the westerly portion of Riverside County, has a watershed area of 330 square miles, and there are 248,000 acres of arable land needing irrigation in the valley. The rainfall is only about thirteen inches in the valley and irrigation is essential for agricultural productivity. The water supply being small compared to the area of land to be irrigated, the controversy between the various parties developing the valley had resulted.

To furnish information for the equitable adjustment of claims between the various parties, the Division of Engineering and Irrigation entered into a contract with five of the organizations in the valley and with the Division of Water Rights, for investigating the water resources of the valley and their utilization. The Division of Engineering and Irrigation subscribed $1,000 to this work and the use of an automobile and other equipment, while the Division of Water Rights subscribed $2,000 and the local interests $5,000. The work is now in progress under the direction of the Division of Water Rights and it is expected to reach completion in the spring of 1923.

Water Resources of Mono Basin.

Resulting from much controversy over water rights and rights of way over federal lands in the Mono Lake Drainage Basin, a resolution was passed by the Mono County grand jury in 1921 requesting that an

investigation be made by the Division of Engineering and Irrigation. An engineer was assigned to this work, the history of the acquirement of these rights was reviewed, the plans for additional development examined, and a report is being prepared.

COLORADO RIVER COMMISSION.

The Colorado River flows southerly along the entire eastern boundary of Imperial County, California. During the past twenty years a very prosperous community has been developed in the Imperial Valley, Imperial County, under the authorization of our irrigation district laws. The irrigation district contains something over 500,000 acres of very fertile land, and secures its entire water supply from the Colorado River. During the low water flow of the river of three seasons within the past eighteen years, there has been a shortage of water for irrigation. A larger area of land is now being irrigated and a larger amount of water is needed, hence a much more serious condition is anticipated in the future because of the sure occurrence of other seasons of scant supply.

The other extreme as to the amount of water flowing down the Colorado River, namely: that of floods, creates a very serious condition also. The Imperial Valley Irrigation District has been compelled during a number of years past to spend large amounts of money in constructing and maintaining levees with which to form barriers against the entry of the river into the valley and into the Salton Sea. In order that protection may be provided for flood damage, and in order that additional water above that now used may be conserved for low flow seasons, and to serve for the extension of the irrigable area: it is necessary that impounding works be constructed at some point on the river. The irrigation district has been cooperating with the U. S. Reclamation Service for some years in investigating the best site for such impounding works.

The proposal on the part of the State of California to so plan and protect the interests of Imperial County is of interest to the other states lying within the basin of the Colorado River drainage area, and in order that there may be general community interest and a general working plan adopted by all such states, certain legislation was proposed and passed by all of them during the year 1921. California's Act is expressed in the language of chapter 88, Statutes of 1921, and is as follows:

CHAPTER 88.

An act authorizing the governor of California to appoint a representative of the State of California to serve upon a joint commission composed of representatives of the states of Arizona, California, Colorado, Nevada, New Mexico, Utah, Wyoming and the United States of America, and constituted for the purpose of negotiating and entering into an agreement between the several states hereinabove mentioned and between said states and the United States of America, subject to the consent of Congress, respecting further use and disposition of the waters of the Colorado River and streams tributary thereto, and