Measuring streamflow in Wissahickon Creek
Watershed assessments provide technical information that is used to guide planning and restoration efforts. The Office of Watersheds also provides technical assistance to our project partners and watershed stakeholders for data collection, data analysis, public education, and information technology tasks.
Living things can tell us a lot about the health of the city’s aquatic resources. We assess three primary types of aquatic life: algae, aquatic invertebrates (bugs), and fish. These three groups can be thought of as a simple food chain. Algae are producers, since they are small plants that provide food for the other parts of the food chain. Aquatic invertebrates include small animals, such as insects, crustaceans, mollusks, and worms. Some invertebrates are consumers that eat algae, while some are predators that eat other invertebrates. Most fish are predators that eat other animals. We assess all levels of the food chain to see ensure they are healthy.
Filamentous green algae (left), dragonfly nymph (center), river herring (right)
Water is essential to all forms of life, but when water contains excessive amounts of pollution or not enough oxygen, living things are stressed and can even die. Water quality can change over the course of a day, and very quickly indeed when stormwater runoff enters our creeks and rivers. For this reason, we continuously evaluate water quality by using submerged water quality probes and by taking frequent water samples during storm events. This type of monitoring allows us to understand water quality changes and obtain detailed information about water quality problems.
Water quality is not the only requirement for healthy aquatic communities. Fish and other aquatic animals need habitat with appropriate depth, flow, and stream bottom characteristics. We assess stream habitat and flow conditions using a variety of techniques, from simple descriptive information to detailed site surveys and habitat modeling.
Assessing Stream Habitat in Terwood Run, a tributary to Pennypack Creek
We perform detailed longitudinal and cross-sectional surveys of stream channels to help us understand stream processes and inform stream restoration projects. To date, more than 500 stream cross-sectional profiles have been surveyed, and several sites have been analyzed in greater detail.
We work closely with the U.S. Geological Survey to monitor stream flow conditions and water quality at 11 USGS gauges in our watersheds. Each gauge is uniquely adapted to conditions at the site, but all gauges have a water level monitoring device, water quality probes, and telecommunications equipment to upload data to a web server at regular intervals.
PWD staff have walked the entire length of all our streams and tributaries, documenting the presence of infrastructure within stream channels and floodplains.
Exposed pipe in creek bed