High Sierra Topix

Anyone else noticing more algae in high sierra lakes and streams?

On my Yosemite trip around Labor Day weekend, visiting places I had last seen in 2014, I noticed substantial algae in streams where I remember none. For example: the Tuolumne River in Lyell Fork canyon, Maclure Creek at the unnamed lakes about 10,500 feet, and the outlet stream from Ireland Lake at about the same elevation. Maclure Creek has no trail and is little visited. Ireland Lake has a trail, but also lower use. Obviously lots of use in Lyell Fork canyon. But algae amounts appeared to be unrelated to the remoteness of the stream.

I mentioned this to a ranger naturalist at Tuolumne Meadows who agreed that algae appears to be on the increase in the high sierra waters. We speculated this might be due to warmer temperatures caused by global warming? Anybody have any better idea?

-Phil

Adding to my own post...

I thought of another possible explanation for increased algae this year (compared to a few years ago). All that algae needs nutrients. All the big fires of the last few years that filled the Sierra with smoke - and sometimes ash - for weeks were bringing in air-borne nutrients, some of which fell out or precipitated out of the air. Could that be the nutrient source that has increased algae in the streams, where the ash and smoke particulates would accumulate from runoff?

-Phil

The 4 years of drought recently may have contributed. Lake and stream levels got low, thus water warmer, increasing algae.

I have also noticed a lot more algae stringers in the Wind Rivers, where there had previously been none several decades ago. There is a lot of horse use in the Wind Rivers, but that has been pretty constant over time so I do not think it is a "nutrient" thing, rather a warming climate.

A physics professor once told me "if you cannot measure it, it doesn't exist".

Not sure what your comment means. Observation of no algae to big stringers of algae a decade later are real, even if not "measured". Unfortunately many phenomena (algae, nutrient load and water temperatures) are simply not measured due to lack of funding to conduct such research. This does not mean that these observations are not valid.

c9h13no3 wrote: ↑Mon Sep 16, 2019 10:51 pm A physics professor once told me "if you cannot measure it, it doesn't exist".

On the other hand, Descartes said "je pense, donc je suis."
John

https://www.hindawi.com/journals/jeph/2012/760108/
One study...

Thanks for the link to the study, AlmostThere. It confirms the obvious: cattle are terrible water polluters. But the algae I saw this summer was in Yosemite streams, where there hasn't been any livestock grazing since the 1890s. And I saw no algae in the same streams 5 years ago. Still a mystery to me.

Another data point - did a day hike along Sagehen Creek in the Tahoe Forest (eastside) on Saturday. No algae. This creek flows through a developed area with logging roads and possibly some cattle grazing.

-Phil

Pack trains still wander everywhere. And there are a lot more people out there than in previous years, some of them bathing with soap and jumping in without washing off sunscreen or DEET, and I wouldn't doubt that has something to do with it. It only takes a little chemistry to alter the balance.

viewtopic.php?f=1&t=17130

Purely speculation, but high water years do tend to move more material (Rock, boulders, gravels, sediment, etc.) around with runoff. Lower elevation reservoirs tend to have higher nutrient content in high water years. I expect that may be a factor in this discussion, but again, just a guess on my part.