Water planners around the world are struggling to secure adequate supplies to meet humanity’s growing needs for water. Until recently, little formal recognition was given to the fact that fish and other aquatic species need water too. In recent decades scientists have amassed considerable evidence that a river’s natural flow regime – its variable pattern of high and low flows – exerts great influence on river health.

With careful planning and management, human needs for water can be met while minimally altering the natural flow patterns that sustain ecosystem health. The Conservancy is providing global leadership in environmental flow science and management. To help others implement this cutting-edge work, program scientists provide tools, training and information, and they continue to develop and refine new methods for protecting freshwater habitats.

The Conservancy’s Darran Crabtree, director of conservation science in the Upper Allegheny Basin in Pennsylvania, answers questions about his freshwater work in Pennsylvania as well as conservation efforts of Lake Ontario and the Chiapas region of Mexico.

nature.org: What’s your role at The Nature Conservancy?

Darran Crabtree: I’m the director of conservation science in the Upper Allegheny Basin, working in both Pennsylvania and central and western New York. My job is to use science to evaluate strategies for freshwater conservation and determine new strategies to conserve these systems. 

nature.org: Where do you focus most of your work?

Darran Crabtree: I work primarily in the rivers of the Upper Allegheny Basin, which includes both New York and Pennsylvania.  I also spend part of my time contributing to the conservation efforts of Lake Ontario and the Chiapas region of Mexico.

nature.org: What’s the most important project on which you’re working?

Darran Crabtree: Working with the Eastern Region’s Conservation Science Office, we’re rolling out a satellite imaging tool that will guide land protection efforts along rivers. We’ll use this imagery to determine areas throughout the Upper Allegheny Basin that are prone to flooding. Those flood-prone areas help to maintain the natural flow and erosion-sedimentation cycles of a river.

It’s a great example of how conservation benefits both people and nature. Many of the flood-prone areas we’re focusing on for the natural needs of the rivers also are some of the same areas that often have caused economic and human loss during flooding. Simultaneously we’re helping to conserve the globally significant Upper Allegheny Basin and protecting the interests of humans. It’s a win-win. 

Among the reasons that make the Upper Allegheny Basin globally significant is the fact that it holds the largest and only viable populations of at least two globally rare mussels, the clubshell and the northern riffleshell. The populations here are so large as to make the Upper Allegheny Basin the only place where restoration efforts involving the relocation of those species can be attempted.

nature.org: What is the Conservancy’s goal for this system of rivers?

Darran Crabtree: We’re working in the Upper Allegheny Basin because the rivers are in excellent shape. Our goal is to make sure they stay that way. 

Our long-term goal is to conserve some of the best remaining examples of tributaries to the Ohio River Basin, including the Upper Allegheny Basin, by protecting floodplains and headwaters. Success is natural flowing rivers, chock full of viable native species like the hellbender (a salamander), spotted darter (a small fish) and northern riffleshell (a freshwater mussel). 

We’d like to make sure that the processes important to the habitats and creatures, such as natural flow regimes and the filtering of the river water by the mussels, are preserved for the future.

Nature picture credits (top to bottom, left to right): Photo © George C. Gress/TNC (View of the Susquehanna River); Photo © TNC (Darran Crabtree); Photo © Gary Peeples, U.S. Fish and Wildlife Service (Clubshell).