Julie Zimmerman's work as a river ecologist for The Nature Conservancy stretches from the Connecticut River to the Chesapeake Bay. View a slideshow of the rivers she's helping to protect. Get Involved!   You can learn more and explore new places when you join the Conservancy's online community and build your own personalized nature page. "Look at a list of threatened and endangered species and you see freshwater aquatic species are at the top." — Julie Zimmerman, river ecologist for The Nature Conservancy. Go Deeper Chesapeake Bay Find out what else the Conservancy is doing to help the Chesapeake Bay. Connecticut River Program For more than 40 years, the Conservancy has been working in the Connecticut River landscape — click to learn more. The Nature Conservancy's Freshwater Initiative Freshwater ecosystems are essential to human life. Learn what the Conservancy is doing to protect them.

Julie Zimmerman is a Nature Conservancy river ecologist based in Bethesda, Maryland. Julie sat down with nature.org and spoke about analyzing river flows and working with partners to balance ecosystem needs with human demands for water.

nature.org: So what does a river ecologist do?

Julie Zimmerman: My work focuses on the Connecticut, Susquehanna and Potomac rivers. I divide my time between the Connecticut River Program and the Chesapeake Bay Initiative.

In 2004, the Conservancy launched the Chesapeake Bay Initiative to partner with public and private agencies to protect and restore the bay. I work closely with Mark Bryer, director of the initiative. Mark has the big-picture perspective on the bay’s needs and the local knowledge, while I bring an academic-research background and help answer specific technical questions.
 

nature.org: Here’s a technical question: How’d you get interested in rivers anyway?

Julie Zimmerman: I spent a lot of time at the beach while growing up and then went to college planning to become a marine biologist.

A river project for a hydrology class sparked my interest, and then for my master’s I studied how land-use changes in Puerto Rico’s tropical forests had affected streams and freshwater crabs. I was hooked.

Then I got my Ph.D. in fisheries, researching the effects of non-native trout introductions. So I’ve always been an aquatics person. I just switched from marine to fresh water, although it’s all connected.


nature.org: Why is the Conservancy involved in river flows?

Julie Zimmerman: Look at a list of threatened and endangered species and you see freshwater aquatic species are at the top.

Take Maryland’s largest freshwater fish, the shortnose sturgeon, for example. This is a fish that breeds incredibly slowly — females first spawn at age 11 — so when their habitat becomes degraded, it takes a long time for the population to rebound.

Since water is such a scarce resource, and we’re placing more demand on our rivers, a traditional land-buying approach can’t protect fish species like the shortnose sturgeon. We need broader strategies to protect the whole system — from the Chesapeake Bay, to the headwaters of the Susquehanna, and all the cool freshwater systems in between.
 

nature.org: How important are freshwater flows to the Chesapeake Bay?

Julie Zimmerman: The balance of fresh and salt water makes the Chesapeake Bay ecosystem what it is. The Susquehanna contributes 50 percent of the bay’s fresh water, and the second-largest contributor is the Potomac, so their flows obviously affect that balance.

For example, say natural summer flows are fairly steady, but then you build a hydropower dam that suddenly creates huge fluctuations every few hours. You’ve changed the dynamics of how and when nutrients and sediments are pulsed into the bay and how salinity is distributed. We know species respond, but we’re still working toward being able to say, when this happens with river flows, then these are the exact consequences. Solving that equation is an overarching goal for my three river projects.
 

nature.org: How do you engage with partners?

Julie Zimmerman: Many rivers have a specific agency — the Susquehanna River Basin Commission, the Interstate Commission on the Potomac River Basin — whose mission is conserving water resources through regulation or collaboration.

Federal and state agencies also regulate such uses as water withdrawals and hydropower dams. The Conservancy also has a nationwide partnership with the Army Corps of Engineers to address flow issues.

The agencies usually welcome us as partners, because we bring new ideas and research and can help develop new methods they feel comfortable adopting.

 
nature.org: What keeps you coming back to work every day?

Julie Zimmerman: I’ve always loved field research and just being outside by a beautiful river. Although these days I spend more time at my desk, I feel more effective at making a difference. I still like the research — figuring out the questions no one’s answered — but it’s rewarding to work with partners who can take that information and help our rivers.

Nature picture credits (top to bottom, left to right): Photo © TNC (Julie Zimmerman); Photo © Jerry and Marcy Monkman (Kayakers paddle the Connecticut River in Old Lyme, Connecticut); Photo © Jerry and March Monkman (Aerial photograph of the wetlands in Maryland's Fishing Bay Wildlife Management Area).