This past Wednesday, Ashley and I got the amazing opportunity to go stream sampling with Andrea and Benjamin Glass-Siegel, who works with the Baltimore Ecosystem Study (BES). BES is based in University of Maryland, Baltimore County, and is collecting data on the Gwynns Falls watershed water quality over a period of 50 years. That’s a long time and a whole lot of data! BES is actually one of the only long-term studies in the world investigating the effects of urbanization on ecology and one of only two in the United States (the other one is in Phoenix, Arizona). Water quality isn’t the only aspect of the Baltimore are that they are researching: they are also looking at vegetation, soil, biodiversity, and how data connects to demographic and social aspects of Baltimore. Check out their website HERE!
Stream sampling has been going on for the past 15 years and has been constantly changing and adapting to new technology and opportunities. For instance, at the first site, Ben showed us a device (hidden and locked under an old oil can to prevent vandalism) that gathers data from the Gwynns Falls every few minutes. Ben visits each site along the stream once a week and uploads the data from the device onto his computer. The device also collects a sample of water every few minutes into a bin stored underneath the device. Every week, Ben samples the water collected over the seven days and then cleans out the bin, preparing it for a new week of sampling.
Ben surveys about ten sites along the Gwynns Falls watershed, from around where the stream starts in Baltimore County to where the stream becomes a rushing river in Baltimore City. At every site, he gathers data on the dissolved oxygen (DO), pH, conductivity (similar to turbidity, or how clear the water is), and the water level/height (compared to a standard ruler on the side). He also gathers samples to take back to the lab to test for turbidity and other factors not measurable in the field. Since many scientists are intrigued by the long-term nature of the project, Ben also gathers other samples for other scientists. One bottle that we filled on Wednesday, for instance, was for another scientist’s study on the levels of pharmaceuticals in the water. Because Baltimore often allows sewage to overflow into stream water (see below for more on that), pharmaceuticals from human waste can be detected in the water samples we take — this could provide valuable data on what medicine people tend to use, legally or illegally.
The water quality of the sites varies drastically. One sampling site is located right near the end of I-70, and in the winter, because of all the salt used on the roads (salt lowers water’s freezing point), Ben has recorded water temperatures below freezing, but the water isn’t frozen! At another spot out in Baltimore County, there is almost no trash cluttering the banks, but there is severe erosion on one side of the stream because of a housing development that extends to just a few feet from the water’s edge. On the other side, with no houses, the bank looks perfectly fine and natural. The juxtaposition is stunning, and it was amazing to see how certain factors can dramatically reduce water quality, and thus, the biodiversity.
All along the stream, however, erosion was common, and so were raised sewer outfall locations. Ben explained that sewers were commonly built next to streams back in the day because streams exhibit sites of natural liquid flow (gravity causes the water to flow downstream), so the sewage in the sewers would obviously be able to flow in the same downstream direction, thus reducing the need for expensive pumps to mobilize the sewage.
Indeed, in Baltimore, we’ve been struggling with a lot of sewage overflows into our streams! Repairs are moving along, slowly but surely. At one of the sampling sites, a raised black pipe (thankfully, sealed while we were there) ran down the hill, through the water, and up the other bank. The pipe was temporarily funneling sewage from one location to another while crews fixed the sewage pipes underground.
What a cool experience overall. We ended the day sampling a few sites out in Oregon Ridge Park. These stream sites are used as control areas because of their pristine water quality and little to no nearby urbanization. The forest was calm and serene and the water perfectly clear. It was almost like a reminder of what Baltimore used to look like. Could we potentially restore some of our urban streams to be as pure as this one?