October 2011 monitoring

Posted by: upperwalnutcreekaustin | October 10, 2011

October 2011 monitoring

We monitored during the morning of October 8. The sky was overcast but no rain at that time – later that afternoon/evening we had about 1.5 inches. But during the visit everything was dry, dry, dry.

The stream continues to shrink under the bridge, though the storm drain’s flow has increased noticeably since the last visit. Not sure why.

The surface algae has grown to cover much more of the stream since last month. Above the waterfall (upstream of the bridge) there is new surface and submerged algae by the banks and none in the middle, as the photos below show. Upstream of the waterfall for the first time there were some dry patches in the middle of the stream; I was able to walk into the stream and take one of the downstream photos without getting my feet wet – a first.

The sample pool has an oily sheen on the water. We tried to move it aside while dipping the bucket but couldn’t – it immediately returned. We saw some decent-size turtles (about a half dozen, roughly 6″ shell diameter) around the sample site, along with lots of minnow-size fish.

Thankfully the air temperature is lower, it was actually enjoyable outside for a change! Here are the stats:

air temp:       26 C (79 F)
water temp:   23 C (73 F)
dissolved oxygen: 2.53 (much better than last month!)
specific conductance: 520
pH:                 7.5
nitrates:       0.25
the water was very clear – there are very few particles in the water. It’s the clearest I can recall with the transparency tube reading being greater than 1.2 meters (the highest it measures).

Given the increased flow from the storm drain, unsurprisingly the e-coli counts are up again. The sample site averages 1361 colonies, triple the acceptable level. The upstream control have about 482 colonies.