Page 13 - labwp1929annual

BOARD OF WATER A ,\"D POWER COilliU1SSJOSERS 11

that the ground base was very dry and in a condition to readily absorb
a large proportion of the water from melting snow. The resulting imme-
diate yield of water, therefore, has been relatively small.
Yearly Mean Per Cent Yearly Mean Per Cent
.Year 111 Sec. Fe et of lIIea11 Year In Sec. Feet of Mean
1906-07 670 190 1918-19 335 95
1907-08 457 130 1919-20 231 66
1908-09 387 110 1920-21 225 64
1909-10 437 124 1921-22 330 94
1910-11 440 125 1922-23 321 91
1911-12 494 140 1923-24 211 60
1912-13 253 72 1924-25 149 42
1913-14 395 112 1925-26 230 65
1914-15 457 130 1926-27 275 78
1915-16 477 136 1927-28 309 88
1916-17 437 124 1928-29 198 56
1917-18 380 108
PUMPING OPERATIONS
In order to furnish an adequate supply of water through the Aque-
duct, it has been necessary to operate all of the available wells in the
Independence region south of the Poverty Hills throughout the entire
year. An average of 52 wells operated during the year, pumped the
equivalent of 75 second feet continuous flow, or a total of 52,698 acre
feet of water. With the exception of six wells in the vicinity of Aberdeen,
which have operated part time for irrigation, all of the wells in the
Independence region have been supplying water to the Aqueduct.
The attached table shows the monthly means of number of wells
operated, second feet and acre feet output from the Independence region
for the fiscal year 1928-29.
MAINTENANCE AND OPERATION
The present year has been one unusually free from interruptions in
the flow of the Aqueduct, only one shut-off having been made. This was
for a period of five days in April for the purpose of making the annual
inspection. This inspection showed, that with the exception of occasional
spots of eroded and rough bottom from Haiwee south, and spots of
rough side wall immediately north of Haiwee, the Aqueduct is in excellent
condition and capable of delivering its full designed capacity of 400
second feet.
TINEMAHA RESERVOIR
The Tinemaha Reservoir which is capable of impounding 16,627 acre
feet of water, has just been completed. Work on this project was started
January 2nd, 1927, and involved the construction of an earthfill dam
with heavy rock protecting face; outlet works having a maximum
capacity of 1300 second feet; a 10,000 second foot overflow spillway; and
the relocation and construction of seven miles of the Southern Pacific
Company's narrow gauge railroad.
The dam, which has a maximum height of 35 feet and a total length
of 5853 feet, contains 423,000 cubic yards of dry earth-fill and 73,000
cubic yards of black lava rock obtained from excavation of the spillway
at the east end of the dam was used to riprap its upstream face. This
facing varies from 24 feet thick horizontally at the crest of the dam,
to 10 feet thick at the lower toe. This rock makes an excellent protecting
face against wave action, as it has a specific gravity of 2.75 and con-
sists of uniformly graded sizes, ranging from small pebbles to rock
having a maximum diameter of five feet.
The outlet control works consists of a 20 foot diameter, concrete gate
tower, located near the upper toe of the dam at its westerly end and
provided with three 4 foot by 5 foot sluice gates hydraulically operated.
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