MUNICIPAL WATER SUPPLY OF SEATTLE

MUNICIPAL WATER SUPPLY OF SEATTLE

In a contributed article in the Cornell Civil Engineer upon the above subject, the following data is given: Cedar Lake, shown in Fig. 1, lies well in

Cedar Lake, shown in Fig. 1, lies well up in the watershed at an elevation of 1,530 feet, and was somewhat enlarged by the construction of a wooden dam, so that its present area is about two square miles, and its capacity one billion cubic feet. This lake serves as a storage basin to equalize the flow to the present power plant which is situated about four miles below the dam. The river, from the dam to the power house, makes a total fall of 600 feet, and the water for the wheels is carried the whole distance in woodslave and steel penstocks, one of which is I and the other 0 feet in diameter. Figures 2 and 3 show typical falls in the stream. Twelve miles below the power house is a low wooden dam, Fig. 4, which diverts the stream to the gravity conduits leading to the city reservoirs. I hese conduits are two in number and both constructed, in the main, of fir wood stave, although each pipe has short sections of riveted steel. The first conduit which was built varies in size from 42 to 54 inches in diameter and was placed in commission in January, 1901, and delivers about twenty-two and one-half million gallons per day. The second varies from 48 to 60 inches in diameter. was put in service in June, 1909, and can deliver forty-four and one-half million gallons daily. These lines are about 28 miles long, and there is a total drop from the intake (elevation 535.83) to the intermediate service reservoir in Volunteer Park (elevation 420) of 115.83 feet. Work has already started on the construction of a new dam for increasing the storage capacity at Cedar Lake. It is proposed to raise the level of the lake from its present elevation of 1,530 feet to an elevation of 1,605 feel, thus extending its area to five and one-fourth square miles, and increasing its capacity for storage to eight billion cubic feet. The dam will be of “cyclopean.” concrete. gravity type with entire height above the river bed of 185 feet, an approximate length of 640 feet, and wiil contain about 80,000 cubic yards of masonry. This additional storage will enable the city to increase the capacity of its present power plant from 14,000 to 60,000 horsepower uniform output. The combined capacity of the distributing reservoirs of the city totals about 270 milllion gallons, a reasonable ten days’ supply for the present population of 250,000. Sites for additional reservoirs have been chosen and these will be constructed as soon as they may be needed. At the present time there are 36,310 water accounts of which 22,500, or about 03 per cent, are metered. For domestic metered service a minimum charge of 50 cents per month is made, up to a consumption of 500 cubic feet. For the next 1,000 cubic feet, a charge of 12 1/2 cents per 100 is made, and 6 cents per 100 for all consumption per month above 1,500. These are exceptionally low rates when compared with other cities of this class, and if studied in connection with the following brief statement of the receipts and expenditures for 1010 will throw clear light upon Seattle’s success with a municipally owned water supply:

FIG. 1. CEDAR LAKE, SOURCE OP WATER SUPPLY OF SEATTLE, WASH.FIG. 2. UPPER FALLS OF CEDAR RIVER.

The expense account includes operation and maintenance, charges, interest and redemption and an item of nearly $57,000 charged in the official report to “reconstruction.” Excess or net earnings arc entered into the capital investment account and used in new construction. It should he kept in mind that the water supply system of Seattle is very closely related to her power development schemes and that the financial success of these municipally owned public utilities will have an important effect upon the future growth and development of the city. Few tide-water cities of the world are so favorably located in close proximity to almost unbounded Water power, and none, so far as the writer is aware, have an opportunity to develop approximately 90,000 horsepower within territory absolutely owned by the municipality. The effect that such ownership will have in fixing the charge for power for manufacturing purposes and preventing a monopoly cannot he over estimated.

That the citizens of Seattle are pretty definitely committed to the principles of municipal ownership of public utilities is sufficiently proven by the fact that they have already made a cash investment in a water system and a power plant amounting to more than $13,000,000, and have recently voted additional bonds in the sum of upwards of nine million for extensions and improvements on what they have and to inaugurate a municipally owned street car line. The present power plant of 14.000-horsepower capacity furnishes electric current largely for street and domestic lighting purposes, but when extended as proposed to its capacity of 60,000-horsepower, the will he fully justified in entering the field as a competitor in street railway business. In 1890 Seattle committed herself to municipal ownership by the purchase of the “Spring Hill” water system, paying therefore about $352,000. The next year the “Union W ater Company” property was bought for $28,300 and since that time numerous small plants have been purchased from private parties as the territory supplied by them was brought within the city limits. Mr. R. H. Thomson, city engineer, early appreciated the fact that great aggregations of population would follow the development of the Pacific Northwest and he foresaw that Seattle would not he the least of these coming cities. He therefore felt that some source of water supply must be sought and acquired capable of development in capacity sufficient to furnish ample quantities even though future population should be numbered in millions. An investigation of available sources of supply led to the adoption of the Cedar river as satisfactory in all particulars. The drainage area of this stream extends from the south end of Lake Washington in a southeasterly direction to the summit of the Cascade mountains, a distance of about 50 miles, and that portion of this area that lies above the intake embraces about 136 square miles. On the basis of measurements extending over a period of nine years (1902-1910) the average yield of this area is about 683 sec. feet, or about 450 million gallons per day. If 150 gallons per capita per day be taken as a fair allowance, the run-off of this stream is capable of supplying a population of 3,000,000 people. In order to prevent the pollution of this magnificent supply, and to be in a position to control the drainage area, the city early took steps to acquire clear title to it. Twenty-five square miles were purchased outright and 55 square miles are now under condemnation. Of the balance, 36 square miles are held in the government forest reserve, but the last Congress took action which places this area practically in the possession of the city, with some stipulations regarding the removal of the timber. The other holdings are the unsurveyed lands of the Northern Pacific Railway Company, and these, no doubt, will in time come under the city’s control. The territory is now regularly patrolled by inspectors of the city health department, who are given ample authority to make their work effective.

An interesting situation arose in 1906, when the Chicago Milwaukee and St. Paul Railway sought from the city a right-of-way through 11 miles of the drainage area above the intake for their Puget sound extension. The city granted the privilege after favorable report had been summitted by a commission especially constitutetd to whom the matter was referred for settlement. This commission was made up of Dr. A. C. Abbott, of Philadelphia, representing the city; Dr. Charles Harrington, of Harvard, and secretary of the Massachusetts state board of health, representing the King county (Seattle) Medical Society, and Professor Sedwick, of the Massachusetts Institute of Technology, representing the railroad company. The state board of health took independent action in the matter and employed Mr. John R. Freeman. M. Am. Soc. C. E., to report on the best methods of protecting the river from pollution during the construction of the railroad, and later when it should be in operation. Mr. Freeman’s recommendations contemplated the strictest sanitary supervision of all construction camps, and the practical isolation of the right of-way of the railroad from the river by a series of dikes and ditches draining to dry porous gravel, so that the water thus collected “might filter away through a safe distance of not too coarse earth before reaching the river.” These recommendations were strictly carried out during the construction of the railway under the supervision of the state board of health. The writer had occasion quite recently to go over this work rather critically, and found no reason to believe that the means adopted for protection against contamination front the railroad are not serving their purpose in a most satisfactory and certain manner.

FIG. 3. LOWER FALLS OF CEDAR RIVER.FIG. 4. DAM AND INTAKE OF CEDAR RIVER WATER SUPPLY, SEATTLE.

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