Implementing environmental flows in semi-regulated and unregulated rivers using a flexible framework: case studies from Tasmania, Australia

Despite the many methodologies available for undertaking environmental flow assessments, there are few published examples of environmental flow recommendations that arise from those assessments, and even fewer that evaluate their implementation. This is somewhat surprising considering environmental flow recommendations are effectively testable hypotheses of flow-ecology responses. We describe a framework to guide the assessment and recommendation of environmental flow regimes in Tasmania, Australia, where environmental values are highly catchment specific and rivers are largely semi-regulated or unregulated. This means that environmental flows must be focussed on setting water use thresholds to prevent degradation in condition, rather than delivering water to restore condition. The framework retains the philosophy and elements of many other methodologies but differs by having the flexibility to support application across different catchments while catering for catchment-specific issues. We present two case studies that demonstrate the application of our Framework, its use in the development of scientifically defensible environmental flow recommendations, and their implementation in catchment water management plans. The strengths of the Framework are: (i) using specific ecosystem values to define and communicate the objectives of environmental flows; (ii) using a non-prescriptive and flexible approach to incorporate catchment-specific issues; and (iii) framing recommendations in a manner that clearly illustrates flow linkages with ecosystem values so that stakeholders and managers understand the risks associated with water abstraction. Our experience demonstrates the imperative that scientists are not only involved in water planning but also in the implementation, monitoring, and evaluation of plans so that the benefits of adaptive management can be realized.