After World War II, the number of tourists visiting Crater Lake be gain to increase dramatically. An estimated two hundred hours and people were now visiting the lake each summer, requiring the Park Service to upgrade its sewage-disposal facilities. In 1946 and 1947, a septic tank-drainfield system was installed on the caldera rim near the Crater Lake lodge. Although it was known that sewage water percolated through drainfield soils, park managers made no attempt to determine if sewage was entering the lake. Instead, independent scientists continued to document the limnological properties of the lake, apparently unaware of the potential lake-damaging hazard posed by the new sewage-disposal system.

Bathymetric chart of Crater Lake, Oregon, showing sampling station locations, created by J. V. Byrne in 1965. Byrne, John V. 1965. Morphometry of Crater Lake, Oregon. Limnol. Oceanogr. 10: 462-465. Used with permission.