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July 17, 2015 Quality Testing Notes

posted Aug 15, 2015, 9:37 PM by Derek Brown
Despite the heat, traffic congestion and detours, and faulty data sheets, we had a very successful morning on the streams on July 18th. A good turnout, including two new testers from LFP and two folks from the SnoKIng Watershed Council who were interested in observing what we do. We visited 10 sites; one of our usuals was skipped due to low water and inaccessibility.

Here is a synopsis of that data posted at Quality Data 2015

Dissolved Oxygen: The highest result was 13 (mg/l.); the lowest 6. All others were in the 9 - 11 range. The 6, on Lyon Creek, just below the culvert collapse at Ballinger Automotive, is definitely lower than what is good for fish, and might warrant some follow up testing over the next few weeks.

pH (acidity): Five locations recorded this at more than 7.5, which is the value we most frequently find. This is interesting in that King County, in its stream monitoring program, notes a long term trend for Lyon and McAleer Creeks towards lower pH values, meaning the streams are slowly becoming more acidic. Go figure.

Turbidity: Two sites were cloudy; the others were clear.

Temperature: These measures were very interesting given the hot spring and summer we’ve had. The average temp for Lyon Cr. and its tributaries was 65.2F., which was noticeably warmer than the average for McAleer Cr. and its tributaries at 60F. Looking back at the July 2014 and 2013 temp readings, this relationship is also the case, although not by so wide a margin. 68F was noted on Lyon Cr. at the Town Center. That temp is close to the range where biologists say bad things begin to happen to salmon and trout.

Interesting to speculate about the different temperatures in our two stream systems. McAleer generally has a little more water volume - maybe that makes it a little cooler. McAleer starts in a lake (Lk. Ballinger) - maybe that tends to moderate the temperature towards cooler. It might also indicate that McAleer has more tree cover over its length. I think a case can be made that more shade along Lyon Cr. would improve its fish habitat function, especially in periods of extreme warm weather.

Bacteria: Several of us attended a workshop recently where we learned a simple method for screening stream water for e. coli and other bacteria. So we took samples at 5 locations in order to try it out. The samples were mixed with a measured amount of growth medium and cultured in a petri dish for 30 hours. A styrofoam box with a light inside served as the incubator. The results indicate low levels of e. coli and other bacteria at all 5 locations.  The sample from McAleer Cr. where it enters LFP at 196th St. (near the former Guitarville store) developed the most colonies - see the file below. The 2 darkest colonies are e. coli; the other red/pink colonies are non-e. coli bacteria.

Obviously great caution is needed in interpreting these results. It was our first time doing the test, so there could have been “operator errors” at several points. However it is a test that could add a new dimension to our overall monitoring program, and one that we may want to work with more in the future.

Looking to the future, the City has once again asked that we conduct an insect inventory on our streams in the fall - we collect the samples, they pay for an aquatic entomologist to do the analysis. We have set Saturday, Oct. 3, 9:00-12:00 to do this. I’ll send out a reminder as the date gets closer - hope you can join us.
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