November 2019

Posted by: upperwalnutcreekaustin | November 17, 2019

November 2019

November 16, a gorgeous, cool day. It has rained several inches since the last time we were here. There’s a lot of debris around, both from the previously higher stream and also, sadly, human trash in the culvert.

Someone had placed rocks and a log by the trail crossing so walkers could cross with dry feet. The gravel bar that was between the bridge and the trail crossing (though mostly under the bridge) is still completely gone.

The stream seemed to be a bit higher than last time – on the upstream side of the bridge you’d need to jump a bit to cross the stream. No surprise given the much-needed rain. The higher water level (before today) scoured all of the algae, including all of the underwater algae. All of the algae around the edge of the waterfall is gone – and the water is falling across the entire width of the waterfall. Even so, the water level upstream of the waterfall was low, so the “sometime island” rocks in the middle of the stream were dry.

We didn’t see pigeons (pigeon poop is a possible e-coli source) or other birds and no fish anywhere, just a turtle by the sample site. The lack of fish isn’t surprising given the chilly water (50 F). The dissolved oxygen was much higher than last time and the stream was crystal clear; there were few to no dissolved solids. This is important as that affects the amount of sunlight that reaches submerged aquatic plants.

E-coli was almost nonexistent. With 3 ml samples, there were about 50 colonies at the sample site and 33 colonies at the upstream control site by the waterfall.

Observations:

air temp: 12.5 C (54.5 F)
water temp: 10 (50 F)
dissolved oxygen 9 (80% saturation)
specific conductance 470
pH 7.0
nitrates < 0.3
transparency > 1.2 meters