Posted by: upperwalnutcreekaustin | May 9, 2012

May 5, 2012 Monitoring

Cloudy and not too hot (for a change – it’s been warmer than usual lately (low 90s instead of mid 80s). I’m ready for cooler weather…and rain! Haven’t had any in over a month, the green is starting to go brown and there have been fire warnings.

One area is significantly greener than last time…the surface of the stream. Above the bridge, much of the water is almost completely covered with algae (see photos below). Hoping for rain which will clear out some of this!

Most of the readings are usual, the notable exception is the e-coli. It’s again up over 1500 colonies (acceptable  is under 400).

Other info:

air temp 26 C
water temp 23.5 C
Dissolved oxygen 5.2
pH 7.5
Nitrate 1.0
Transparency (dissolved solids) – .98 meters

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Posted by: upperwalnutcreekaustin | April 9, 2012

April 2012 Monitoring

April 8 – beautiful weather, sunny and not too hot, though it’s definitely been warmer than usual for this time of year.

I noticed several changes as soon as we arrived.

  • the surface algae has spread further upstream above the waterfall
  • the shopping cart that had been under the bridge is gone. Did someone move it or (more likely) was it washed downstream by a strong current after the last heavy rain?
  • the gravel bar near the sample pool has expanded – the surface area has nearly doubled since February’s photos, probably thanks to a couple of 3 to 4 inch rains. (See the photos taken just after the last 3.5″ rain last month, it’s an interesting contrast in the water levels). Currently the only area that water flows past the gravel bar is next to the south bank; now it’s possible to cross the stream without getting your feet wet – that was the case months ago due to some good-size flat rocks but they have been gone for nearly a year now.  The narrow passage makes a pleasant gurgling sound…but if the water level gets much lower, that may end up creating  fairly stagnant pool.

Further algae observations: when looking at last month’s photos, I noticed that the surface algae above the bridge and waterfall was significant though not quite as extensive as this month, and that there wasn’t much difference in the algae below the bridge. But notice the two photos of the March 20 stream after the (roughly) 3-4 inches of rain. What did that do to the extensive surface upstream algae? Given the apparent force of the water, I would expect that it would have washed away much of the surface algae, and probably much of the underwater algae (I have no idea how firmly algae is anchored to the stream bed). If that was the case, then there was an impressive algae bloom in 3 weeks upstream.  What happened to algae downstream of the bridge? Why isn’t there much of a change?

Other observations:

The flow of the stream is strong enough that the waterfall sound is loud enough to be easily heard. The storm culvert also has a lot of water flowing through it into the stream.

There are plenty of small fish (minnows) and we also saw a couple of small perch. The water is close to its usual level, both under the bridge – the columns are covered – and at the sample pool the water level is much closer to the usual level than it was last year, per the watermarks on the rocks (see the photo).  Although there is much surface and underwater algae upstream of the bridge and waterfall, there is little algae and no surface scum at the sample site.

The vital statistics – normal:

  • Air temp: 22.5 (72 F)
  • water temp 20 (68 F)
  • dissolved oxygen 4.5 – 50% saturation
  • pH 7.0
  • specific conductance 650 (near the high end of the normal range of 350-700)
  • nitrates 0.75 (acceptable)
  • transparency (amount of dissolved solids): > 1.2 meters, the height of the transparency tube.

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Posted by: upperwalnutcreekaustin | March 5, 2012

March 2012 Monitoring

March 4: a great day to “march forth” and monitor. The sky was clear and the temperature was cool but absolutely beautiful! I’ll be thinking about this during the summer heat for sure!

We’ve noticed some significant changes in the stream, mostly in algae level – from last month to now it went from non to wow! Algae aside, the stream is incredibly clear. The flow from the storm culvert is strong. Under the bridge the stream is the normal width, covering the columns (same as last month). The gravel bar is still there, and someone has added planks so people can walk across without getting wet feet.

I’m wondering if there was another relatively heavy rain or strong flow for some other reason because the metal shopping cart (probably from the nearby HEB) was under the bridge last month and now it’s upstream of the bridge near the waterfall. Assuming no one moved it, how did it get there? Curious.

Looking far upstream from the site and beyond the waterfall area, the total volume of the stream has reduced enough to let some rocks in the middle of the stream show above the water; last month they were completely submerged. And in that area the stream doesn’t reach quite as far up the banks (see the photos).

Observations and measurements:
air temp 15 C (59 F)
water temp 13 C (55 F)
specific conductance 650
dissolved oxygen, 6.5 (65% saturation)

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Posted by: upperwalnutcreekaustin | February 5, 2012

February 2012 Monitoring

February 4, an overcast, cool day. Last night it rained about 1/4 inch at our house (about 3 miles NW from this site); other areas had 1-4 inches of rain. Ten days ago we had 2.5″ of rain at the house and a friend who lives about 3 miles the opposite direction from this site had 5″ of rain. So I’m guessing that this site had 3-4 inches at least. It shows.

The water is much higher than last month – the 3 bridge columns are finally under water. Based on the debris, the water was fairly high after the heavy rain last week, though nothing like in Sept 2010 when tropical storm Hermine dumped 10″ of rain.

We noticed that there is a new gravel bar (like a sand bar…but with gravel instead of sand) between the bridge and our sample pool, just barely upstream of where the trail from the south bank park crosses the stream. This gravel bar is barely covered by the stream now; I expect that next month at least parts of it will be dry unless the rains continue (here’s hoping!). Also, there is no surface algae and very little submerged algae – all of the long strands from last month are gone, probably washed away.

The current is strong and the waterfall is full, we could hear it as we walked down from the car to the stream. The storm culvert also has a strong flow into the stream, and we saw a lot of new debris fairly high above the stream (see the photos). We’ll see how the e-coli levels have changed…

Turns out the e-coli counts are at acceptable levels. Based on 1 ML samples, there are 135 colonies at the sample site, and the control site upstream has half of that, 75 colonies

The stats:
air temp: 13 C
water temp 16 C
specific conductance 450
dissolved oxygen 8.7 (80% saturation)
transparency (with floating solids): .58 meter (not surprising given the recent rains)
pH 7.5
nitrates .5

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Posted in LCRA monitoring, water quality

Posted by: upperwalnutcreekaustin | January 8, 2012

January 2012 monitoring

The morning of January 7, 2012. A beautiful day – sunny, air temp of 13 C (55 F)…and unfortunately, high cedar pollen (sniff, sneeze).

The stream is looking somewhat better since we had 5 inches of rain last month. It is a bit higher, easily seen because 2 of the 3 bridge columns are now in the water. A bit surprisingly, the nitrates reading doubled from 0,25 to 0.5 mg/L. Although higher, it’s not cause for alarm (the less accurate test would have shown it as under 1, which is acceptable).

Water temperature is 14 C (57 F)
The dissolved oxygen is 8.1, or about 80% – well within the normal range for this time of year.
Specific conductance is 640
pH is 7.5 (normal)
the water was extremely clear. The bottom of our meter-long transparency tube has a silver button in the center surrounded by black and white sections; we could see both the colors and the center button clearly when the tube was full, which is unusual.

There is enough flow that the waterfall is clearly audible.
Above the waterfall, in the shallow water (maybe 6 inches deep), the algae has grown to long strings. There are also a lot of underwater clumps of algae, and a fair amount of surface algae as well.

There is also a good flow of water from the storm culvert, which usually seems to influence the e-coli below it.

E-coli at the sample site (below the culvert) is within acceptable limits an average of 318 colonies from two 3 ml samples. At the control site upstream of the culvert, the 3 ml samples only had an average of 33 colonies.

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Posted in LCRA monitoring, water quality

Posted by: upperwalnutcreekaustin | December 4, 2011

December 2011 monitoring

Wonderful rain! It has rained 1.5 inches since mid November…including almost 1/4 inch in the last few days.  The stream is definitely higher – the bridge pillars are finally in water for the first time in months. While walking down besides the culvert/creek that flows into the stream, we noticed new trash alongside that stream, as though it had been a stronger flow (see photo). And there were also pools under the bridge where water had flowed. Today it has been misty/drizzling. It stopped long enough for us to monitor – great timing.

We noticed a cylindrical net by the sample pool (see the photo) and during our monitoring 2 sisters walked down to the stream from the apartments. Turns out it’s their net, they use it to see what they can find in the water. They have pulled out a snapping turtle and occasionally a fish, which they return to the stream. We cautioned them about the usually elevated e-coli bacteria and explained that it’s not safe to drink that water and may not be safe to eat fish from the stream

Observations:

Plenty of minnows. There is no surface algae, and the “possibly surface invasive” plants from last month have retreated. The waterfall flow is strong enough that we could hear the gurgle…for the first time in months.  It’s a wonderful sound. The area around the culvert is muddy where there was a stronger flow, and between the bridge and sample site the crossing rocks are under water.

There’s enough water flowing over the waterfall that we can actually hear the gurgle, a sound that has been missing for the last months. And there are ripples above the waterfall – wonderful to see.  Further upstream, where the stream bed is about 12 ft wide, the elevated middle part of the stream bed is nearly covered with water.  The side where I’ve been walking upstream is now under water, so I didn’t go as far as I have recently.

Water temp: 16 C (60 F)

Air temp: 17 C (62 F)

Dissolved Oxygen: 7.45 (75%)

Specific conductance: 410

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Posted in LCRA monitoring, water quality

Posted by: upperwalnutcreekaustin | November 30, 2011

November 2011 monitoring

Cloudy and cool.  And no significant rain since the day after last month’s monitoring. Surprisingly, there was still some flow in the storm culvert (albeit with a scummy surface) .  There’s dead algae and new surface algae at the entrance from the culvert, near the sample site and upstream. Possibly from last month’s rain? The water level under the bridge hasn’t changed noticeably, as I look back at last month’s photos.

Along with the obviously dead plants up and down the stream, others are turning colors – it’s sometimes hard to decide if they are dying or the leaves are just turning colors before they drop for the winter.

There are some possibly invasive plants starting to cover the water between the trail and the bridge. LCRA tentatively identified them as water primrose

The stats for this visit:

  • Air temp: 19 C (66 F)
  • water temp 13 C (55 F)
  • Dissolved Oxygen 2.33
  • pH 7.5 (usual)
  • Nitrates 0.25 (usual – low, which is good)

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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.

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Posted in e-coli, LCRA monitoring, water quality

Posted by: upperwalnutcreekaustin | September 4, 2011

September 2011 monitoring

September 3… day 79 of 100+ degree heat. Hopefully it will start cooling down soon – at least it seems to be hitting 100+ a bit later each day.

The stream hasn’t dried up but it’s very low and there’s virtually no flow.  The surface has a bit of a film on it – almost a scum or a sheen. The surface has some algae and new plants have grown into areas of the shallow water. There is also some new submerged algae upstream; the old, dead algae is gone – decomposed? The stream bed above the waterfall is almost uniformly and completely covered with gray-green debris (maybe the old algae) and the new algae is growing through it and from it (see the photos).

Around the waterfall there is much dead algae where the water has receded – apparently “damp” isn’t enough to sustain its growth. And the wooded areas at and beyond the banks are incredibly dry – it’s heartbreaking.

There are numerous tiny fish (baby minnows?) both around the sample site and upstream of the waterfall. We saw what appears to be a fish hatchery about 2 meters upstream of the sample pool – a small area by the bank  was cleared of debris and there were a lot of little fish swimming around there.

As expected, the e-coli counts remain low – a 3 ML sample showed about 116 colonies (below the EPA-established level of 394 colony forming units). If the formerly high levels came from a leaky sewage pipe, the best guess is that the soil surrounding the leak is so dry it’s absorbing the liquid and the bacteria before it reaches the stream. One of the few good things about the drought…and I’m ready for the levels to rise if it means more rain!

Measurements:

Water temp: 25 C (77 F)
Air temp:     31 C (87 F)

As expected, the Dissolved Oxygen was very low, about 0.8 (15%)

Specific Conductance: 460

7.5 pH (neutral / normal)

Nitrates .25 mg/L

Dissolved solids / visibility .79 meters

.

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Posted by: upperwalnutcreekaustin | August 7, 2011

August 2011 monitoring

Hot, hot, hot! This is the 51st (or is it the 52nd?) day of triple digits. High temps have been hovering around 107. It was still 100 at 9 PM last night. And no end – and no rain – in sight.

We’ve had less than half of the normal rain so far this year, and all the plants and animals are suffering. The storm drain that has supplied significant water (and e-coli) to the stream is now merely moist;  it’s the driest we’ve ever seen it since we started monitoring 5 years ago. All of the algae  at the drain”s entrance to the stream is dead or dying, though some other plants are still surviving (see the photos).

Nearly all of the surface algae is also gone, though there is significant algae growth in the stream. The surface scum we saw last month is gone. And surprisingly there is still a tiny trickle of water at the waterfall upstream of the bridge.

At 9 AM the air temp was a mere 28 C (83) – that “chilly” temperature won’t last long. The water temp was 33 C (91 F).

Despite the dissolved oxygen being very low, .75 (about 15%), there are numerous tiny fish. Guess they don’t need much oxygen! I also heard a splash by the trail crossing area but didn’t see what made it – maybe a turtle or snake.

We used a new nitrate test which is more sensitive (see the photo below); it showed .25 nitrates; the regular test showed < 1 (as usual). And the ecoli was very low – good, though probably because of the drought – no water is being added to the stream from the surrounding areas.

Other stats:

  • specific conductance 490
  • pH 7.0
  • nitrates .25
  • dissolved solids (transparency tube): .68 meters

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Posted in water quality

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