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September 27, 2004

Using the World Water Montioring Day kit to test water quality

In a previous post I briefly described World Water Monitoring Day (WWMD), a national water quality testing project. The project seems to be primarily focused towards testing conducted by kids as part of a school project, but anyone can order a rudimentary test kit for $19.95 and enter data collected between now and October 18.

I ordered a kit and did my first monitoring yesterday. Here's how it went.

The World Water Monitoring Day kit from Lamotte. Contents, clockwise from upper right: cannister (for sampling and storage of the rest of the kit), pH tablets, dissolved oxygen test tablets, small sample tubue, 10 ml test tube, thermometers (self-stick, to apply to the cannister), Secchi disk icon (self-stick, to apply to the bottom of the cannister), and a chart to read results.

Taking the sample (in this case, aided by a very handy E-Z Reacher). The sample is actually taken a little deeper, at least 4 inches under the surface. The cannister is held under water for at least a minute.

The temperature is read via the self-stick thermometers on the outside of the cannister.

The dissolved oxygen test is prepared in the small tube. The pH test is prepared in the longer 10ml test tube. There is a short waiting period for both; during this time, the Turbidity measurement can be taken. Turbidity is the measure of relative clarity of the water. This is done by comparing the test chart to the view of the Secchi disk icon sticker at the bottom of the cannister. The laguna water today was very turbid; this might e the result of soil erosion, urban runoff, algal blooms, or bottom sediment disturbances.

Here's where everything fell apart for me: the pH test. I read these results as a "10", which would be "very basic". This seemed odd while I was at the test site. When I returned home and tried to enter this value, the WWMD web site informed me that I had to enter a value between 6 and 8. Since this is a required field, I can't enter any of my data at all (unless I fake the pH data). This doesn't give me a lot of confidence in the system; if others have this problem, I'm guessing that they'll enter any value that works here simply to go on with the data entry.

I'm guessing that my pH test results are in fact wrong; I'm not sure if they're wrong because of a mistake I made in the collecting, or a problem with the test tablets. I tried testing our tap water using the same method, and that came out to be a more reasonable 7 or 8, which seems to indicate that the entire lot of pH tablets probably isn't defective. I have difficulty believing that the pH leve of the laguna is that far off center, because there were lots of little fish and creatures visible in the sampling area.

The Dissolved Oxygen test measures how much oxygen is available in the water. Healthy and stable natural waters usually have high levels of dissolved oxygen. The test results here are combined with the current temperature to determine the saturation, which in this case was 91%.

As I mentioned, I was unable to complete my data entry at the WWMD web site, because the form wouldn't accept my pH value nor let me enter the other results without it. I wasn't able to find additional information on the site about what to do in this situation.

My first foray into water monitoring has resulted in more questions than answers. The manual for the kit warns several times that the tests are not particularly precise, which I can accept, but I'd like more information abou what tools are recommended for higher-level testing. I wonder if the data collected from these rudimentary kits is actually usable by scientists? I also have many questions about how to intelligently interpret the data after collecting it several times, so I'd appreciate recommendations on further reading on the topic. (I'm sending a link to this post to the folks at WWMD in case they can help with any of these questions.)

In any case, I intend to do some more testing throughout the month to see if the results vary overtime. I'll need to educate myself on some of these topics for sure, because people walking by as I was taking samples were very interested in what I was doing and asked lots of questions (I'll probably make a couple copies of the WWMD brochure to take with me next time just so they don't think I'm a total crackpot).

Although I was hoping to find a nationally-based data collection program, I should mention that there are a lot of other water monitoring groups out there, and many of them do very precise data collection. A good starting point for more information on these groups is the EPA volunteer monitoring page. I hope to post additional information about some of these efforts (and maybe even participate in some) in the coming months.

Posted by terrie at September 27, 2004 07:01 AM

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Comments

Posted by: Colin Gregory Palmer at September 27, 2004 01:01 PM

Posted by: Terrie at September 29, 2004 07:31 AM

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