2026 SAV Intern Experience with DNREC

Written by 2026 DNREC SAV Program Intern, Josie Murphy

When people think about maps, they usually think of forests, wetlands, or other places that are easy to see. But what about the plants growing underwater? Submerged aquatic vegetation (SAV), often called underwater grasses, grows below the surface of Delaware's rivers, bays, and ponds, making it much harder to monitor. This summer, during my internship with. Delaware's SAV Program, I got to see firsthand how scientists use sonar and GIS to map these hidden underwater habitats.

SAV is made up of rooted plants that grow completely underwater in areas where enough

sunlight reaches the bottom. These underwater meadows provide food and shelter for fish, blue crabs, turtles, and many other aquatic animals. They also help improve water quality by trapping sediment, taking up excess nutrients, and helping keep the water clear. Because SAV is so important to healthy waterways, it's important for scientists to know where it's growing and how those areas change over time.

The process starts out on the water. I had the chance to go out on the survey boat while sonar data was being collected. As the boat followed planned survey lines, the sonar system, which was actually just a recreational fish finder, continuously sent sound waves to the bottom and recorded the echoes that bounced back. Those echoes can tell us where underwater plants are growing, even though we can't always see them from the surface.

Once the fieldwork is finished, the data still needs a lot of processing before it becomes useful on maps. During my internship, I worked with the sonar data in GIS. After the data was obtained, I converted them into raster datasets, using PINGMAPPER, a software designed by Cam Bodine to convert sonar data into usable forms. Each square contains information about the habitat below the water, allowing scientists to clearly see where SAV is growing across an entire waterway.

These maps are used for much more than just showing where underwater plants are found.

Scientists can compare maps from different years to see how SAV is changing, identify areas that may need restoration, and better understand how water quality affects these important habitats. The maps also help guide future conservation efforts throughout Delaware.

One of my favorite parts of this internship is getting to be involved in both the fieldwork and the GIS side of the project. It was really interesting to see the entire process, from collecting data on the boat to turning that information into maps that scientists can actually use. Before this summer, I had never thought about how underwater plants were mapped, but now I have a whole new appreciation for the work that goes into monitoring Delaware's waterways. From days in the field to time spent working with data, the summer offered a firsthand look at the many pieces that come together to support SAV restoration efforts across the state!