FEATURES AND WATER RIGHTS OF YUBA RIVER. 145 



vicinity of French Coral without water, that portion of the ditch between North San 

 Juan and French Coral was turned over to Mr. Thomas, of Birchville, who agreed to 

 keep up the ditch and deliver the water to the farmers. The company gave Mr. 

 Thomas the 200 inches of water, and allowed him all he could make for keeping the 

 ditch up. Mr. Thomas maintained the i-ates previously given. 



Irrigation is very limited in this vicinity, there being in all about 500 acres 

 watered from this ditch. The crops irrigated are alfalfa, fruits, and vegetables. 

 The practice is to irrigate gardens every three or four days, alfalfa every twelve 

 to thirteen days, and orchards every fourteen to sixteen days. 



The duty of water will always be low, as the soil is a shallow red clay, and tne 

 temperature during the irrigation season is quite high. About 10 inches of water 

 used every seven days during the season of sixteen weeks will irrigate 2 acres. 



NORTH BLOOMFIELD GRAVEL AND ^HNING CX5MPANT. 



The North Bloomfield Gravel and Mining Companj- was incorporated in 1866. 

 Its water rights are located on the same watershed as those of the Summit Water 

 and Irrigation Company, but lower down on Canj'on Creek, and embrace the overflow 

 from the Summit Water and Irrigation Company's reservoirs, together with an 

 additional catchment area of 19 square miles. The principal reservoir is Bowmans 

 Lake, which is situated about 6 miles east of Graniteville on Canyon Creek, a tribu- 

 tary of the South Fork. This reservoi*!' was designed for the supply of water during 

 the drj" season to work the gravel mines which were owned by the company. 



In ordinary seasons the Summit Water and Irrigation Company's reservoirs 

 retain all the water flowing from the catchment area of Bowmans Lake, which has 

 an extent of about 19 square miles. The mean annual rainfall at Bowmans is about 

 75 inches, of which 75 per cent is run off. Two dams are required to impound the 

 water at Bowmans. The main one, placed across the narrow gorge forming the 

 outlet of the valle}', has a maximum height of 100 feet (96.25 feet above the datum 

 base line) and an extreme length on top of 425 feet. The smaller dam, placed across 

 a gap near the mouth of the valley, has a maximum height of 54 feet and an extreme 

 length of 210 feet. It is fitted with wastewa\s, and over it is discharged the excess 

 above the capacity of the i-eservoir. High-water mark is fixed at a point 1.5 feet 

 below the crest of the main dam. At this height the reservoir, with a surface area 

 of over 500 acres, contains 918,000,000 cubic feet of water. By placing flash boards 

 on the top of the wasteway the water is raised to the 96-foot level (above datum 

 base), increasing the capacity of the reservoir to 930,000,000 cubic feet. The stream 

 feeding the reservoir has a maximum flow during great freshets of 5,000 to 7,000 

 cubic feet per second. The dams at Bowmans Lake have been designed to with- 

 stand not only freshets, but also any additional strain due to the breaking of the 

 dams above. The main dam cost $15,000. It rests on solid granite bed rock. In 

 1872 a timber-crib dam was built to the height of 72 feet, the crib being built of cedar 

 and tamarack logs, notched and bolted together, and solidly filled with loose stones 

 of large size. A water-tight skin of pine planking is spiked to the upper face. 

 During 1875-76 the dam was increased to a height of 100 feet by filling in a stone 

 embankment on the lower side of the old structure, faced with heavy walls of dry 



23856— No. 100—01 10 



