The taxpayers will be called upon to spend more money if the city engineer is to attempt to make the new city reservoir at Cedar river water tight.

How much the experiment will cost is problematical. City Engineer Dimock estimates that to line the leaking north bank of the impounding basin with clay will cost about $3,000 a month, most of the equipment being now on hand.

If, as former City Engineer Thomson believed might be possible, the sealing process takes five years, the experiment will cost only $180,000.

Mr. Thomson planned as last resort to attempt to seal the bank by forcing liquid cement into the mile and a half of gravel bank. A conservative estimate of the cost of this would be $3,000,000. Engineers admit that the figure is only wild guesswork. The job might cost much more.

The present city engineer does not think the Thomson plan practicable.

Taxpayers may take what consolation they can from these two estimates: Mr. Dimock's conservative figures amounting to $180,000 and the guess at the Thomson plan of $3,000,000.

Then the question still remains--will the reservoir be sealed?

So far as the dam itself is concerned, the huge masonry cork which stops the outflow of the Cedar lake has proved all that the builders hoped it to be. It is a water-tight structure, and its month of test shows it entirely stable and reliable.

Never at any time is there danger of the dam being undermined nor of a flood descending upon the people of the valley below. The structure is anchored securely to bedrock.

The leakage, which has cast grave doubts on the process of the entire product, is a slow seepage extending perhaps a mile and a half along the coarse gravel bank of the north side of the canyon. It appears on the other side in wet spots and springs and in the enlargement of several streams flowing into the Snoqualmie watershed.

Mr. Dimock said yesterday that the greater volume of the water had begun to flow back into the Cedar river channel some distance below, or west, of the face of the masonry dam. The coarse gravel has simply offered a channel for the river to circumvent the big wall.

Mr Dimock is authority for the statement that the actual rate of fall of water behind the big wall is one inch an hour. The water is now at a depth of approximately fifty feet. Figures based on the water area of the impounding basin when the water is at this height against the face of the dam show a loss in cubic feet of 6,000,000 a day. In a year this leakage would, at the present rate, amount to 2,190,000,000 cubic feet. Two billion feet leakage a year would amount to almost a third loss of the water impounded.

In addition to this, it is pointed out by engineers that when the water is raised to the full elevation of the dam, that is when the full 6,000,000,000 or more cubic feet of water is stored, as planned, the pressure will be greatly increased and the tendency to leak much higher.

The fact is established by the most conservative authority, that of the city engineer, that the great project costing a million and a half dollars promises to be one-third below estimated capacity. Mr. Dimock, who inherited the project from his preecessor, Mr. Thomson, is hopeful that this will be remedied at low cost.

The experts who warned the city that this would happen, who urged that proper investigations be made before a million and a half dollars was spent, pointed out conditions which promised even greater loss of efficiency.

Particularly interesting in this connection is a forgotten report by Prof. Henry Landes, acting president of the University of Washington and state geologist, and Dean Milnor Roberts, of the same institution. On July 12, 1910, these experts warned the city that Cedar lake has a disused subterranean outlet to the Snoqualmie valley. They predicted that if the tremendous body of water contemplated was stored behind the dam it would very likely find an outlet along the old river channel.

It is possible that Cedar lake, tired of being harnessed by man, has turned back to this old fault.

The story of the old channel goes back to pre-glacial days. Before the ice came, said the geologists, Cedar lake found its way into the Snoqualmie or possibly by a more roundabout course back to the present valley.

"The pre-glacial course of Cedar river was doubtless as at present until it approached the vicinity of camp 2 (where the great dam now stands)," they wrote, "when it probably veered to the right (or north) and either entered the Snoqulamie valley along the chain of swamps and lakes at the foot of Rattlesnake mountain or swept around the rocky hill east of the station of Moncton and entered the present valley in the vicinity of the municipal power plant. The changes in the river course were produced by the glaciers of the Cedar and Snoqualmie valleys, which deposited great moraines along the sides and bottoms of the valleys. The waters of Cedar lake are ponded by a dam of glacial sediment which lies athwart the valley.

These geologists were called into consultation through the efforts of R. H. Ober, who was put in charge of the dam construction. Mr. Ober felt that the city had not made proper surveys, taken proper precautions before deciding to spend its money in locating a dam at the present site. He located the buried river channel at its outlet by sounding Cedar lake. There seemed to be no question that underlying deposits left by the glaciers is the original channel of Cedar river, filled now with loose bowlders, coarse gravel and sand.

A great body of water impounded above this old fault might easily be forced by its own weight into the subterranean tunnel, where it would gradually seep away into an entirely different watershed, reaching the Sound by way of the Snoqualmie.

The geologists believed this would happen. They wrote in the same report of July, 1910:

"The probabilities almost amount to a certainty that there will be a large loss from the lake by seepage around the north end of the dam unless great precautions are taken."

The precautions recommended were the buildiing of a wing from the north end of the dam northeasterly toward Cedar lake.

"It may be necessary to continue the curtain wall even to the mountain spur to the north of the present lake," they wrote.

Being geologists and not engineers, they did not concern themselves very greatly with the question of cost of a concrete wall three or four miles long and how many feet to bedrock nobody could say. Its cost would be many times the value of the entire watershed plant.

The water department has spent the $1,100,000 of bonds voted for the dam project. In addition it has drawn on city resources to continue the work. More than a million and a half has been spent, the last work being finished upon the assurance of the council to the board of public works that it would pay the bills.

Faced by the necessity of spending still more, Mr. Dimock will ask authority. No engineer will stake his reputation on the success of the expenditure, and the most Mr. Dimock or any honest engineer can say is to express the hope that the sealing of the leaking north bank will not add much more to the cost of the project.

"If it costs several millions," said Mr. Dimock yesterday, "the success of our city light plant justifies it. If we have to throw the whole thing into the Sound, still the success of the light plant justifies it. The results obtained by the plant are an invaluable return upon the money invested."