DCVA's Stream Watch is a yearly study of water quality in the Darby Creek watershed. Each spring Stream Watch volunteers help collect macroinvertebrates from several locations in the Darby Creek. These organisms are categorized as as 'pollution tolerant', 'pollution sensitive', or 'facultative'- meaning they can live in healthy or in impaired (polluted) environments. The same spots are checked every year so that we can watch the quality of the water in the creeks over time. Next we identify the organisms and calculate a biotic index- a mathematical measure of stream health based on the proportions of pollution tolerant, pollution sensitive, and facultative types of organisms at the study sites.
We welcome volunteers who wish to learn the stream side and the laboratory techniques! Please contact Alan Samel at firstname.lastname@example.org to be notified of future Stream Watch volunteer opportunities.
This year we had our annual Insect Identification Workshop on January 25, 2020 at the Haverford Reserve, taking a look at the samples we took from stream on April 6, 2019.
With about 15 years of data at some of the sites, we have a pretty good idea of what to expect, and what would surprise us. For example, the Havertown site just downstream from the Haverford Reserve trends over time to be in the fair-good range for water quality; this year is no different. At the other end, the Skunk Hollow water quality is almost always very good. This year that water quality metric went down to fair. Why? It was a warm winter, so that could be it. Or, was it something else? We really won’t know until we sample that site again to see if there is a continued trend down or if it was just a one year blip. Check out the chart below to see the annual trends at different sites from 2004-2020.
Unfortunately, we were not able to conduct our annual stream watch spring collection event in 2020 due to the Covid-19 virus. The stream watch collection is very time sensitive and must occur in the early spring before the aquatic insects emerge as adults. We need these insects because they tell us a lot about the water quality at that site at that time. If we collect mayflies, which are very sensitive to stress, then that is the indication of a stream location with high water quality. If we collect no mayflies at a location but expect them to be there, then that is an indication that this site might be stressed. It is unfortunate to lose an entire year, but we know that we can depend on our army of volunteers to be ready to go in 2021. In the meantime, stay healthy, protect our waters and watershed!
Full Article : Another Successful Insect Identification Workshop!