Probing the Depths of Crater Lake: A Century of Scientific Research by Douglas Larson
The Park Service proceeded to study the lake, as directed, but the agency continued to stall on the issue of sewage contamination. Meanwhile, during the summer of 1983, scientists made another unsettling discovery. Chemical analyses of spring waters emerging along the caldera wall and flowing into the lake indicated that one of the springs contained roughly ten times more nitrogen than any of the other forty to fifty caldera springs tested. Using maps and sketchy geological information, the scientists determined that this nitrogen-enriched spring, called Spring 42, was part of a groundwater aquifer flowing directly beneath the septic tank-drainfield system. The scientists surmised that septic wastewater was percolating through drainfield soils into the aquifer. This information was passed on to J. F. Quinlan, an outspoken Park Service geologist, who strongly recommended that a dye-injection study be conducted immediately to trace the pathway of wastewater seepage through underlying soils and rock. Unfortunately, this work was never attempted, and the question of sewage contamination was never resolved.
Since 1984, as part of the ten-year lake-monitoring program, the Park Service has funded several limnological investigations of the lake, including (1) additional research on phytoplankton by David McIntire of OSU; (2) a zooplankton study by Elena Karnaugh of OSU, who discovered nine rotifer species; and (3) precise chemical and isotopic analyses of Crater Lake water by J. M. Thompson and Manual Nathenson of the USGS. Oceanographers Robert Collier and Jack Dymond of OSU have conducted extensive research on the lake’s mixing processes, temperature and oxygen gradients, water and sediment chemistry, and the recycling of nutrients from phytoplankton and other organic matter that settles through the water column. In 1988 and 1989, the two researchers explored the lake’s great depth with a one-person submarine called Deep Rover. They searched for evidence of geothermal activity on the lake bottom and found bacterial mats associated with what they believed to be thermal springs. In 1993, the National Park Service provided Congress with a progress report on the first ten years of the Crater Lake monitoring and research program. The program was extended for an additional ten years at a estimated cost of $1.6 million. The second phase of the program is currently under way. Whether the Park Service intends to continue the program after the second phase, which terminates in 2002, is uncertain. Perhaps by then both the Park Service and Congress will recognize that long-term monitoring and research are essential for the protection of Crater Lake, and they will continue to support successive ten-year studies. Recently, the North American Lake Management Society (NALMS) published a monograph on the limnology of Crater Lake, which included papers on the limnological program mandated by Congress in 1982, the lake’s physical and chemical attributes, and the lake’s biology.
And the sewage problem? In 1991, thirteen years after first being alerted to the possibility of sewage contamination in Crater Lake, the Park Service quietly removed its lake-polluting septic tanks from the caldera rim and diverted the sewage through a new $3 million pipeline. Coincidentally, since then the lake’s remarkable water clarity has been more or less restored. In August 1994, the Secchi disk was observed to a depth of 134 feet. But whether this improvement in water clarity resulted from sewage diversion is still unknown.