TO HATCHERY men who have spent night after night raking leaves, rubbish and anchor ice to maintainwater flow, the possibility of an intake, self-cleaning and fool-proof, should be welcome news. The construction of such an intake at the St. Johnsbury, Vermont, station of the Bureau of Fisheries, converting what was undoubtedly the world's worst to what is perhaps the world's best, is an accomplished fact.
The principles involved have been worked out over a long period of years in stream diversionwork at the National Forest, New Hampshire, station.Here, owing to the wide area covered by the work, it has been necessary to provide intakes requiring the minimum of human attention. These principles have been perfected in the recent construction at St. $ob•bury.The Sleepers River is, of course, anything but a satisfactory hatchery water supply.Draining miles of cultivated land among the hills of several townships, its s,,wm•r flow is very limited.A s,•r shower, however, may put it over its banks; spring and autumn floods are excessive, and it often runs full of slush ice at times of freezing temperatures.In spite of these difficulties, the station is producing most excellent land%oc•ed salmon fingerlings and yearlings.The original intake, like so many with which the writer has been familiar, could hardly have been designed to give more trouble if that had been the object in view.It consisted of a log crib dam, about 4 feet high, at the crest of a 30 foot fall.A masonry, breakwater, built well above freshet pitch, extended from the bank above, on the intake end, to the toe of the dam. The hatchery supply eddied around the lower end of this breakwater, between it and the crest of the dam, flowed back up inside the breakwater, in a sort of forebay, addled again around the upper end of the intake bulkhead and passed to the intake pipes, at the lower en• of the bulkhead.During periods of flood, yards on yards of silt, sand and gravel were deposited in the forebay eddies, often damming its entrance completely.It was frequently necessary to coffer dam the entrance from the river, drain the forebay and shovel tons of debris over the breakwater wall. 0nly a large storage reservoir, on the hillside below the dam, rendered the hatchery operation possible at such times.Leaves and other trash, drawn into the forebay, passed to the intake screen, making frequent brushing necessary.Anchor ice always bothered when the air temperature dropped below 10 ø F, until the flowage above the dam froze completely over. This ice would freeze to the intake screen, which had to be brushed almost continuously.