The stream-watch program is an assessment of water quality at several sites in the Darby Creek Watershed based on the aquatic organism collected and identified. The program has two components: the spring streamside sampling and the winter insect identification workshop. It’s hard to believe that we have been doing this for over 20 years!

The 2025 Stream Watch stream samples were collected April 13th. We took ten samples: two from each of five sites up and down Darby Creek. I’d like to say thank you to the small army of volunteers who helped make this a great day. What a day! The stream was running a little higher and faster than base flow due to heavy rains within an earlier 48-hour period. We were able to take all the samples we needed! Our day started at a cool 55°F and was overcast. Many thanks to the seven brave and committed people who made this a success!

The insects and bugs we collected provided a snapshot of the health of Darby Creek. This was the 18th year of intense sample collections and identifications. From this long-term sampling, a trend of the stream health at each site has been determined. Each year we compare our findings with the water quality determinations from previous years. It’s a way of getting the big picture from a lot of very small bugs! The annual Insect Identification Workshop was on January 11th, at the Haverford Reserve. We had a great turnout, more than 30 people! We were able to process all the samples in record time! Attached is a figure depicting the water quality of each sample site over time.

The water quality results are in and 2024 looks like a good year compared to previous years. Four of the five sites saw an increase in water quality. Bartram Park, Darby Borough there was a very slight decrease in water quality but remained in ‘Fair’ category, which has been where this site has been classified through the years. Three of the four sites that improved since last year resulted in a good water quality classification. One of the sites, Skunk Hollow, did improve but is still in the ‘Fair’ classification. The Skunk Hollow result is becoming a concern because this was at one time the most diverse site in the DCVA Stream Watch Program, but in the past 8-10 years the water quality has decreased from very good to good to fair.

One water quality reading from each site does not indicate that a change in water quality has really occurred. Often it takes many data points to determine potential impacts to sample sites, as discussed above with Skunk Hollow. This is the challenge of monitoring a stream in a heavy suburban-urban watershed. Sometimes the cause of the data is not readily apparent. For example, the 2023 samples were taken a short time after heavy rainfall and the stream was still running high and fast at all sample sites. The low counts in 2023 could be because many of the resident bugs were washed downstream; how far no one really knows. This is why one sample date cannot be used as an overall assessment of the water quality at the sampling point. It takes a number of years and a number of data points for a trend to be revealed in the data. After almost 20 years of sampling, we have a fairly good idea of the water quality at each site where we take samples. Every year we learn something new about the stream, the bugs, and watershed.

The upcoming stream sample date will be in April 2025. Stay tuned for the exact date. We will continue to sample from our five established sites. If you are interested in getting involved with the stream watch program; stream samples and insect identification workshop, please contact me at alan.samel@gmail.com.