A Horizontal Intragravel Pipe for Sampling Water Quality in Salmonid Spawning Gravel

Abstract

A new sampler, the horizontal intragravel pipe, was developed for collecting samples of intragravel water in salmonid spawning gravel. The device is a 2.54 × 76.2-cm length of slotted polyvinyl chloride pipe that is buried perpendicular to flow in the streambed. The slots (about 320/pipe) through which the intragravel water flows were cut perpendicular to the long axis of the pipe. Each slot is 1.9 cm long by 0.15 mm wide. A rigid plastic tube (0.64 cm inside diameter) centered axially within the intragravel pipe is perforated with three 3.2-mm holes equally spaced along its length to distribute equally the effect of pumping. The interior tube is connected by Tygon tubing to a peristaltic pump on a platform above the water surface. Intragravel water is pumped to containers for on-site measurement of dissolved oxygen, pH, and specific conductance, and for determination of other constituents in the laboratory. The principal advantages of a horizontal intragravel pipe are that a substantial quantity of water can be withdrawn for analysis, and samples of water may be integrated across an artificial redd.