September 2017 monitoring

Sept. 10 – beautiful weather! Sunny and cool. It’s been cooler than usual since Hurricane Harvey, 2 weeks ago. No complaints for the cooler temperatures. We had about 6-8″ of rain from Harvey and none since. The stream is about the same level as last month, maybe slightly higher – all 4 bridge columns are in the water. And there’s less submerged algae, probably due to a high water from Harvey and a stronger than usual current scouring the stream bed.

While walking down the path to the stream which follows the storm culvert inflow, we noticed that one section of the culvert is backed up has a very scummy surface. At that point (as shows in the photos below), roots and branches block the main water flow just like a dam, so the only way for the water to continue to the stream is by percolating through the “wall” of dirt and branches. That “wall” is acting somewhat like a filter. Not sure what water testing of the scummy pool would show… and that will remain a mystery as it would be a bit tricky to climb down to reach the water. Regardless, as usual, there is a good flow of water from the culvert into the main stream.

There is a slight flow over a small section of the waterfall, just like last month. We saw numerous gambusia (minnows) and some water walkers but no other fish, and no birds or pigeons.

The surface of the sample site was slightly scummy, though not nearly as bad as it has been in the past. The stream is low enough to walk across the trial crossing with dry feet – there’s only a narrow section of the water that flows downstream. On the upstream side of the bridge, nearly the stream bed is submerged at least a bit. Even so, upstream of the waterfall and dry inlet, the stream was low enough that I could easily walk to the dry “sometime island” rocks and even beyond them without getting my feet wet.

E-coli at the sample site was about 283 colonies per 3 ML sample, about twice the concentration of the control site above the storm culvert. Both of these are acceptable levels for an urban stream.

Observations:

Air temp 25 C
Water temp 22 C
Dissolved oxygen 5.5
pH 7.0
Specific Conductance 600
Nitrates 0.6
Transparency  >1.2 meters

 

sample site and beyond from stream side

by trail crossing limited flow

submerged algae patches near sometime island rocks

trail crossing from streamside

trail crossing to sample site from north bank

flowers growing in rocks near trail crossing

stream under bridge to trail crossing from north bank

stream under bridge from stream side

all 4 columns in water

upstream side of bridge

view of stream above and under bridge from culvert

upstream view of culvert and stream

stream from above culvert

closeup of culvert opening

scummy inflowing culvert

inflowing culvert-scummy area and beyond

stream below waterfall area

waterfall area

waterfall area

stream and algae below waterfall

dry inlet above waterfall

general waterfall area

patches of submerged algae above waterfall

school of gambusia

stream above waterfall

submerged algae patches near sometime island rocks

dry sometime island rocks above waterfall

downstream view from above waterfall and inlet

dissolved oxygen 5.5