Removal of excess nitrogen in a hatchery water supply

The water system at the U. S. Fish Cultural Station, Leavenworth, Washington, has been supplemented with two wells that were to be used to increase the temperature of the water during the winter and to cool the Water in the summer if necessary. The well water proved to be unsuitable for hatchery purposes because it was supersaturated with nitrogen, causing "gas-bubble" disease among fish subjected to 11. Mr. R. E. Burrows, the district biologist at the Leavenworth laboratory, devised a system by which the water from one well could be used satisfactorily in the hatchery after a  circuitous routing through a mixing chamber with considerable agitation and a settling basin. The circuitous routing precluded the use of the rearing ponds, and it did not sufficiently reduce the nitrogen tension of the water from the other well.