Managing the Derwent Estuary: 20 years on – success factors, lessons learned and future challenges

Ms Christine Coughanowr1

1CEO, Derwent Estuary Program


The Derwent estuary lies at the heart of the Hobart metropolitan area and is home to 40% of Tasmania’s population, as well as a major centre for commerce, recreation and tourism. The estuary has a long-standing history of heavy metal pollution – with some of the highest reported levels of zinc, mercury and lead in the world. In recent years, there has been significant investment to reduce metal inputs, with considerable success. However, the legacy pollution will require continued investment and careful management for many years to come. More recently, the estuary has shown increasing signs of nutrient stress, including nuisance algal blooms, seagrass loss and persistent low oxygen levels in some areas. Previous research has shown a strong link between nutrient loading, low oxygen and release of heavy metals from sediments. Therefore, a key element of our long-term management strategy is to manage and reduce both heavy metals and nutrients in tandem.

Nonetheless, the Derwent is a beautiful, vibrant waterway with a wide diversity of habitats and species. As the condition of the estuary improves there has been a parallel increase in its use for swimming, boating, fishing and walking.

The Derwent Estuary Program (DEP) is a partnership between government, business, scientists and the community to restore and protect our waterway. Established in 1999, the partnership has been nationally recognised for excellence in reducing water pollution, protecting nature, monitoring river health and promoting greater use and enjoyment of the Derwent. This presentation will provide a brief overview of the current state of the Derwent, how our partnership has evolved over time, and review some of the key challenges going forward.


Christine Coughanowr has been obsessed with the Derwent estuary since she first glimpsed it upon her arrival in Tasmania in 1993.  She has investigated and reported on water quality issues affecting the estuary and its catchment for 25 years, and established the Derwent Estuary Program (DEP) 20 years ago in collaboration with a dedicated team of colleagues and program partners. In 2010, the DEP won Australia’s coveted National Riverprize as a recognised leader in science-based river management.

Previously, Christine worked for UNESCO’s Intergovernmental Oceanographic Commission in Paris and as a water resources management consultant in the United States and France. In 2001, she received a Churchill fellowship to visit estuary management programs in Canada, the U.S. and U.K. She holds a Batchelor of Science degree in geology from Duke University and a Masters of Science degree in estuarine geology from the University of Delaware (USA).