ill., maps; Final report to the U.S. Dept. of the Interior, National Park Service under cooperative agreement no. CA 9000-3-0003, subagreement no. 9.; "October 30, 1987.";
ABSTRACT Four streams outside the caldera of Crater Lake and six springs within the caldera were investigated in 1985-86 to determine if man's activities in the park were altering the water chemistry or aquatic ecology of these streams. Munson Creek had higher concentrations of dissolved inorganic nitrogen and greater biological activity than other study streams outside the caldera. Abundance of benthic algae and rates of primary production were greater in Munson Creek than Sun Creek, Dutton Creek, or Goodbye Creek, and the lower meadow site on Munson Creek tended to be more productive than the upper forested site. Lower Munson Creek also contained higher densities of invertebrates than the other streams. Substrates and organic matter in both sites in Munson Creek supported higher growth rates of caddisflies than similar material from Dutton and Goodbye Creeks. Previous investigations indicated that the greater biological activity in Munson Creek as compared to Sun Creek may not be a recent phenomenon. The close proximity of the maintenance area and the linkages through storm drains present a potential risk to Munson Creek, and Park management should closely review activities and use of hazardous materials on a routine basis. Dutton Creek was less productive and had more depauperate invertebrate communities than the other study streams outside the caldera, reflecting its ephemeral hydrologic nature. There was no evidence to indicate that the septic facility in the headwaters had any measurable influence on the chemistry or ecology of Dutton Creek. Dutton Creek frequently flows intergravel, which restricts the distribution of aquatic biota. Investigation of six caldera springs found that Spring 42, in particular, exhibited high concentrations of nitrate (287 ppb in August 1986); the other springs all contained less than 60 ppb. In Spring 48, there was a rapid uptake of nitrate from the source to the outlet into the lake, decreasing from 58 to 18 ppb. The length of stream and the relative biological activity in different springs may greatly influence the observed water chemistry of the springs where they enter the lake. Biological activity in the study springs corresponded to the observed pattern of nutrient availability. Abundance of benthic algae and rates of gross primary production were highest in Spring 42. At the relative concentrations of nitrogen and phosphorus in these springs, primary production would be limited by inorganic nitrogen; therefore, the elevated primary production in Spring 42 may be a result of the higher nutrient supply. Primary production was also high in Spring 48. The headwaters of Spring 48 were located in a mature conifer forest, and the channel was geomorphically more stable than the other springs. This greater stability may allow development of a more abundant assemblage of primary producers. Primary production in the other springs was less than half of that observed in Springs 42 and 48, which may be related to either lower nitrate concentrations or more unstable channels. Aquatic invertebrates, excluding chironomids, were more abundant in Springs 42 and 48, possibly a result of the higher primary production in these two springs. Invertebrates were most abundant in Spring 48, which may be related to the greater channel stability in this stream. The fauna of these streams were less abundant and included far fewer taxa than those in streams outside the caldera. We suggest that the National Park Service should consider: 1) alternative approaches for treating human wastes on the rim of the caldera of Crater Lake, 2) experimental nutrient uptake studies in the springs of the caldera, integrated with expanded monitoring of water and soil solution chemistry, 3) fluorescent tracer analysis of groundwater dynamics in the caldera rim, and 4) establishment of baseline monitoring of water chemistry in the surface waters of Crater Lake National Park.
ABSTRACT Four streams outside the caldera of Crater Lake and six springs within the caldera were investigated in 1985-86 to determine if man's activities in the park were altering the water chemistry or aquatic ecology of these streams. Munson Creek had higher concentrations of dissolved inorganic nitrogen and greater biological activity than other study streams outside the caldera. Abundance of benthic algae and rates of primary production were greater in Munson Creek than Sun Creek, Dutton Creek, or Goodbye Creek, and the lower meadow site on Munson Creek tended to be more productive than the upper forested site. Lower Munson Creek also contained higher densities of invertebrates than the other streams. Substrates and organic matter in both sites in Munson Creek supported higher growth rates of caddisflies than similar material from Dutton and Goodbye Creeks. Previous investigations indicated that the greater biological activity in Munson Creek as compared to Sun Creek may not be a recent phenomenon. The close proximity of the maintenance area and the linkages through storm drains present a potential risk to Munson Creek, and Park management should closely review activities and use of hazardous materials on a routine basis. Dutton Creek was less productive and had more depauperate invertebrate communities than the other study streams outside the caldera, reflecting its ephemeral hydrologic nature. There was no evidence to indicate that the septic facility in the headwaters had any measurable influence on the chemistry or ecology of Dutton Creek. Dutton Creek frequently flows intergravel, which restricts the distribution of aquatic biota. Investigation of six caldera springs found that Spring 42, in particular, exhibited high concentrations of nitrate (287 ppb in August 1986); the other springs all contained less than 60 ppb. In Spring 48, there was a rapid uptake of nitrate from the source to the outlet into the lake, decreasing from 58 to 18 ppb. The length of stream and the relative biological activity in different springs may greatly influence the observed water chemistry of the springs where they enter the lake. Biological activity in the study springs corresponded to the observed pattern of nutrient availability. Abundance of benthic algae and rates of gross primary production were highest in Spring 42. At the relative concentrations of nitrogen and phosphorus in these springs, primary production would be limited by inorganic nitrogen; therefore, the elevated primary production in Spring 42 may be a result of the higher nutrient supply. Primary production was also high in Spring 48. The headwaters of Spring 48 were located in a mature conifer forest, and the channel was geomorphically more stable than the other springs. This greater stability may allow development of a more abundant assemblage of primary producers. Primary production in the other springs was less than half of that observed in Springs 42 and 48, which may be related to either lower nitrate concentrations or more unstable channels. Aquatic invertebrates, excluding chironomids, were more abundant in Springs 42 and 48, possibly a result of the higher primary production in these two springs. Invertebrates were most abundant in Spring 48, which may be related to the greater channel stability in this stream. The fauna of these streams were less abundant and included far fewer taxa than those in streams outside the caldera. We suggest that the National Park Service should consider: 1) alternative approaches for treating human wastes on the rim of the caldera of Crater Lake, 2) experimental nutrient uptake studies in the springs of the caldera, integrated with expanded monitoring of water and soil solution chemistry, 3) fluorescent tracer analysis of groundwater dynamics in the caldera rim, and 4) establishment of baseline monitoring of water chemistry in the surface waters of Crater Lake National Park.