A lagoon sampler was designed to collect 300-mL samples from depths up to 2.82 m at 15.2-cm intervals. Design parameters required the device to collect discrete samples through the entire lagoon column without cross contamination during raising or lowering of the device through the lagoon and to leave the liquid column undisturbed so subsequent samples could be taken from lower depths at the same location. An evaluation protocol was developed to test the device in a 55.9-cm diameter, 3.35-m tall PVC test column. This test column was of sufficient depth to be representative of lagoons and of sufficient diameter to avoid interference, or edge effects, associated with the sampling device. The evaluation protocol used dissolved solids (sodium chloride) as the test parameter in 30.5-cm deep layers of sodium chloride of decreasing concentrations to fill the test column from the bottom and simulated different solids concentrations that may be found in a lagoon. Samples were collected at six depths from 122 to 198 cm. Based on electrical conductivity measurements, samples collected with the device were slightly more dilute than the expected value at all sample depths. Further tests showed that operation of the device did not cause mixing of the layered salt solutions. The sampler was used to collect samples from various depths in a lagoon; results suggested there was little interference among samples taken at specific locations through subsequent depths.