What might explain the relatively steady level of nitrates in spring 42 some 9 years after the septic leach field was decommissioned?
That’s a good question. I don’t know. We estimated the volume of sewage based on a formula that was used in California. I estimated that about 16 million gallons of liquid sewage per year. Now we could be on the conservative side and cut that in half and say 8 million gallons. Even that is a substantial amount, since 8 million gallons fills 800 railroad tank cars to carry that amount of liquid waste. That’s a lot of liquid waste going into this septic system that’s perched 200 meters above the lake, and only about 200 meters back from the lake in highly porous soils. As I was saying earlier, nitrate is very mobile in soil so you would expect the nitrate to continue to penetrate through the soil profile and be carried down into groundwater, an aquifer which perhaps finds its way to the lake.
As I understand it, the leach field was first placed there after World War I1 when the visitation rate rose rapidly. I think it was originally developed to accommodate about 200,000 people each summer. We have three times more people than that visiting the park each summer now (41). I really can’t explain why the nitrates have remained fairly high over these years. I have no explanation unless the septic system has continued to leach out nitrates and it may do this for some time. I’ve always said that if I’m proved wrong I will certainly admit that I was wrong and accept it. I’m definitely interested in the truth here, and it is possible that sewage was never going into the lake. It was never proved, but neither was it proved as to the effect this sewage might be having on the lake. No one ever proved that sewage was having an inconsequential effect, either.
Is clarity as big an issue now given several world record Secchi disk readings since ’83 as it was 20 years ago?
Coincidentally, it turns out that about the time the sewage pipeline was installed the Secchi disk readings began to increase. I’m not saying, however, that there’s a correlation here, still a lot of unknowns and uncertainty. I’ve never said that there was a definite link between sewage contamination and the lake’s optical properties, but in most lakes there definitely is a link. Anytime the Secchi disk visibility diminishes one always suspects the lake is being contaminated with sewage. Again, I don’t know why nitrates in Spring 42 haven’t diminished in concentration. There are a lot of unknowns in this system but fortunately the clarity has returned to Crater Lake, and indeed some of the readings they’re getting now are 40 or 41 meters. As far as I know 41 meters with the small disk is better than anything that they’ve ever gotten at Crater.
