Stormwater Management

Cathy Jo Branch – Zoo Stormwater Management Project

Program Purpose: Stormwater management for clean water and healthy Nashville crayfish habitat

Sometimes tackling a problem opens up unexpected opportunities and this project is just such a case. The Nashville Zoo and the Cumberland River Compact have joined forces to solve a stormwater issue for the Zoo and improve the water quality and crayfish habitat in Cathy Jo Branch, a small headwater stream that flows through the Zoo grounds.  Working together, a grant was secured by the Compact from the TN Dept. of Agriculture, which enabled collaboration with the Zoo to retrofit a stormwater detention pond on Zoo property, provide training on stormwater best practices, and begin to work with adjacent office park to reduce their stormwater runoff volume and pollution.

Stormwater is simply rainfall runoff that can be both a resource and a management challenge, especially during heavy rainfall events. As we grow and develop, with more rooftops, roads, and parking lots, we create more volume of rainfall runoff. We see it every time it rains, the runoff flows across the land, into storm drains, then directly into our rivers and streams. Stormwater picks up volume, velocity, and pollution on its flow path and the runoff has now become the primary pollution source for our waterways. We can reduce this pollution by improving how we manage our stormwater with both natural and engineered solutions. This project combines both of those to solve a stormwater problem and improve the habitat for the endangered Nashville crayfish in Cathy Jo Branch, a tributary to Seven Mile Creek in the Mill Creek watershed.

The Nashville Zoo has a stormwater detention pond on the edge of Zoo property that serves to capture stormwater runoff from a large office park next door to the Zoo.  The problem is that the parking lot runoff sends excess volume and debris to the pond during heavy rains. Several times a year, excess water is discharged from the pond’s outlet pipe, where it flows through the low, brushy area below the pond carrying sediment and other pollutants into Cathy Jo Branch. There are also issues with runoff from the office park damaging the perimeter fence and carrying trash and debris into the pond.  Working with an expert team of zoo staff, engineers, contractors, and landscape architects, the project team came up with a creative solution that not addresses the stormwater problems but will also create a new feature for the Zoo animals and visitors to enjoy.

The project now underway in 2014 will retrofit the detention pond to modify the two inlets structures and expand the water holding capacity of the pond. In addition, the brushy area below the outfall pipe will become an infiltration zone to slow, spread, and soak in the excess water discharges after rain events.  The low brushy area, which is currently 80% or more invasive privet and honeysuckle plants, will be transformed into a field of native grasses that will be grazed by bison and elk, similar to historic conditions long ago in this region.  Visitors will be able to view this new grazing exhibit area and learn more about the importance of watersheds, native plants, protecting small streams, the Nashville crayfish, and stormwater management. Educational programs will be provided about this project and other stormwater practices for development professionals, homeowners, and other interested parties with events at the Zoo and at the Cumberland River Compact’s River Center in the Bridge Building.


River Steward Spotlight: Kevin Guenther, Landscape Architect   

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Kevin Guenther, Landscape Architect

There is an intimate relationship between our landscapes and the health of our streams and rivers. Working with the designers of our landscapes is a vital part of watershed stewardship. One of the Compact’s longest running collaborating relationships is with the landscape architect Kevin Guenther, who is known for his expertise in natural landscape design, native plant choices, and the principles of permaculture and sustainability.

Kevin has paired with the Cumberland River Compact on many efforts to address water quality issues in Tennessee. One of the most recent projects is our stormwater project with the Nashville Zoo.  This project is focused on improving the health of Cathy Jo Branch with enhanced stormwater practices that include detention pond modification, runoff infiltration with water quality control berms, a restoration of native grass prairie, and creating habitat for a new elk and bison Zoo exhibit.  Kevin contributed to the project with a multi-purpose landscape design concept that will improve water quality of stormwater runoff while also meeting the larger purpose of setting the stage for a new Tennessee Natives Exhibit to demonstrate biodiversity with native ecological habitat and an exciting outdoor educational experience for visitors. Kevin’s project design, called the “Nashville Zoo Native Tennessee Project”, has won a merit award from the American Society of Landscape Architects (ASLA) and will inform the ongoing development of the Nashville Zoo experience.

Kevin has been with Ragan Smith Associates for the past two years, where he brings his 25 years of experience in landscape architectural design and management. Kevin and Ragan-Smith have a strong belief in developing spaces that connect people to their environment and that in that connection comes the desire to sustain a place from one generation to the next. Much of Kevin’s career has focused on applying sustainable design principles to all levels of landscape architecture through a collaborative effort. Kevin believes that every site design is an opportunity to achieve multiple functions including an improved environment, a beautiful place and a well-functioning outdoor space for people to enjoy.

Kevin has also teamed with Cumberland River Compact on other projects such as:

  • Morgan Park Place, the first Earthcraft certified multifamily project in Tennessee, which has earned numerous design awards including the Governors Environmental Stewardship award for excellence in sustainable building. Morgan Park demonstrates improvement of water quality through a treatment train of green roof systems, porous pavers and bio retention areas.
  • Highlands at Ladd Park Open Space Planning and Park Design, which focused on restoring a meadow that serves as a connection to the Harpeth River corridor providing water quality protection, wildlife habitat and recreational green space for residents.
  • Kevin’s personal suburban farm, a place that models harvesting water, energy and food from the suburban environment on a third of an acre lot.

Kevin’s landscape design and native plant selections are one of the educational elements in the professional training workshop on stormwater management and this innovative project, scheduled for November 20, 2015.  The training is designed for engineering, design, and watershed professionals interested in learning about innovative stormwater practices and the value of collaborative approaches to watershed stewardship.


River Steward Spotlight: Dale McGinnity, Nashville Zoo at Grassmere


Dale McGinnity with an elusive hellbender in hand. (Photo: Sherri Reinsch)

Partnerships are vital to the work that the Compact does and one of our favorite partners is the Nashville Zoo.  We are especially fortunate to work with Dale McGinnity, the zoo’s curator of ectotherms. Dale is in charge of the reptiles, amphibians, fish and invertebrates throughout the Zoo. Our current partnership with Dale is focused on the Compact’s stormwater retrofit project to improve the health of Cathy Jo Branch and habitat for Nashville Crayfish.  However, Dale does a whole lot more than that! It’s not unusual for one of stormwater project meetings to follow one of Dale’s alligator wrestling sessions or drawing blood from one of the snakes.

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Dale is a world leader in zoological circles and has worked around the world in pursuit of reptile and aquatic conservation. He’s studied Komodo dragons in Indonesia, giant salamanders in China, and endangered lizards in the Caribbean.  Today, Dale is putting more focus on our native species in Tennessee because, as he puts it, “I think Tennessee streams are some of the most beautiful habitat I have seen anywhere. We are lucky in Tennessee to have the highest freshwater aquatic biodiversity in the country. However, during the last 25 years I have seen a lot of degradation of some of my favorite streams and rivers.”

Dale is also recognized as an expert in conservation of the hellbender – a member of the North American Giant Salamander family.  This prehistoric species was common before 1990 but is rapidly disappearing across the region. The Cumberland River system is especially hard hit. Dale is developing techniques to cryopreserve hellbender milt and improve reproduction. The Nashville Zoo was the first institution to successfully breed eastern hellbenders and the first to breed any hellbenders using artificial fertilization. Dale’s team is working with UT scientists on understanding the health of hellbenders, including challenges from disease and pesticides.

By combining health studies, habitat improvement and hellbender reproduction research, Dale’s team hopes to eventually re-establish hellbender populations back into healthy habitat in future years. With the assistance of Health Canada Pharmacy. Dale reports that “The hellbender is now a candidate species for USFWS endangered status listing and we hope that we can determine the causes and improve the situation so that hellbenders do not need to be added to the endangered species list.”Thankfully the Zoo is working on several native aquatic programs. One of those is a USFWS funded project to conduct long term population monitoring of the federally endangered Nashville Crayfish found only in the Mill Creek watershed.  Dale notes that we sit in the center of worldwide crayfish biodiversity and his research is central to identifying methods to protect and keep our stream species thriving.  One of the biggest threats to our native crayfish is when fishermen spread non-native crayfish from their bait buckets. Dale’s work is aimed at establishing stronger native crayfish populations back into their historic range as a hedge against threats to their survival, such as invasive species or a toxic spill.

The Compact is fortunate indeed to work with Dale and all the dedicated Nashville Zoo staff to protect Cathy Jo Branch, an important headwater streams that so many Zoo visitors are able to appreciate and learn about here in our watershed. We look forward to completing the stormwater project and ongoing collaborations for habitat protection, aquatic biodiversity and conservation education.