Chimney Hill Dam aquatic biota and environmental flow assessment report

Abstract

A survey and assessment of the status of the instream flora and fauna of the Elizabeth River was conducted. The biota are highly modified by the historical effects of the operations of Lake Leake, the modification of the river channel and the introduction of exotic species. The fish community is in a degraded condition. However, key biological values remain, in particular the extensive aquatic plant (macroph yte) communities and their highly diverse and abundant macroinvertebrate fauna, as well as the riparian vegetation which is in particularly good condition. Risks to the instream biota are explored and mitigation requirements identified. A minimum environmental flow regime and operating rules have been developed. Provided the macrophyte assemblages are maintained through appropriate environmental flow management, there are no significant risks to the aquatic biological values of the Elizabeth River from the proposed dam. Key recommendations include: - implementation of a specific minimum environmental flow regime; - integration of management of Lake Leake and the proposed Chimney Hill Dam; - ongoing monitoring of the aquatic biological, water quality and geomorphological condition of the river and storage; - no major changes to operation of either storage without formal review, especially with regard to potential changes to high/flood flow regime.