Water Saving Through Wetland Drying: Review of Environmental Factors Back Creek and Tumudgery Creek

"March 2007".

Project Number: Ecological Survey and ‘Rapid Assessment’ Surveys for Drought Water Recovery - M/BUS/218.

MDFRC item.

1 of 2 reports associated with project see (Water Saving Through Wetland Drying: Review of Environmental Factors - Albury to Corowa).

Murray-Darling Freshwater Research Centre (MDFRC) was contracted by the Department of Natural Resources (NSW) to undertake flora, fauna and site assessments of two wetlands that had been identified as potential sites for water saving. The study area is in the Lower Murray River Catchment on the Edward-Wakool River system near Deniliquin. This report contains the following information: Flora and fauna assessments (microfauna, macrophytes and birds), with particular interest in threatened species, populations and/or ecological communities; 7-part test for all threatened species, populations and ecological communities identified (including fish); and Site assessment for potential adverse impacts (e.g. potential for acidification) and recommend options to ameliorate potential impacts. A site assessment was undertaken on 6th March 2007 of the two wetlands, Back Creek and Tumudgery Creek. The wetlands were assessed by traversing as much of the perimeter as practical, identifying the range of flora and fauna (microfauna, macrophytes and birds) within the study area. The weather conditions experienced during the field investigation were clear skies, temperature of 30°C and light winds. The survey methods employed during these assessments were: • Direct observation of any flora or fauna species within or adjacent to the site; Water quality was tested with a Hydrolab, variables measured included water temperature (°C), conductivity (µs/cm), dissolved oxygen (mg/L), pH and turbidity (NTU); Observations were made of the distribution and presence of woody debris (aquatic and riparian zones), which may act as potential habitat for fish, birds and other animals; Diurnal area searches for bird species were employed. This involved visually searching the study sites from multiple locations around each wetland, including both the aquatic and riparian zones. All birds observed (seen or heard) were identified to establish species diversity; Indirect observations of scats and tracks were recorded to identify the presence of animals within the study area; Active search of both the aquatic and riparian zones was conducted to identify plant species and were recorded to establish species diversity; Sediment testing was completed using Baldwin’s (2006) Decision Support Tool; NSW Department of Primary Industries (DPI) surveyed both wetlands for fish; and A desk top study to locate past surveys of these wetlands to identify threatened species in the region.

This study by design was a brief and preliminary site assessment. Therefore no trapping, spotlighting or vegetation quadrat sampling techniques were used. Given the timing of the survey, early autumn, and due to current drought conditions, it is possible species were overlooked, particularly vegetation which usually flowers in summer or spring and may not be identifiable in the absence of flowers or seeds. Data obtained has been used to compile a list of species that could potentially occur in the area. The data obtained from these surveys is not exhaustive in terms of sampling and should be viewed as an indication of species diversity, representing only a small percentage of what the total species pool could be present seasonally or permanently in the study area. This report has addressed issues with reference to the provisions and requirements of the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act), the New South Wales Fisheries Management Act 1994 (FM Act), the Environment Planning and Assessment Act 1979 (EP&A Act) as amended by the Threatened Species Conservation Act 1995 (TSC Act) and Threatened Species Legislation Amendment Act 2004. Under these Acts various factors need to be considered in deciding whether the proposed actions are likely to have a significant impact on threatened species, populations, ecological communities or their habitat. An assessment of significance, as outlined in the EP&A Act, otherwise known as the 7-part test, is required for all identified threatened species, populations and ecological communities as listed under the FM Act or the TSC Act. Only species listed as threatened under either the FM Act or TSC Act identified within the study region have undertaken further assessment. Other species not listed on these Acts observed or known distribution is within the study area have been included in the report to signify species diversity. A range of migratory birds included in the EBPC Act are listed under international conventions. Many of these are often observed in the vicinity of inland waters within Australia, including the study region. International conventions discussed include: Chinese-Australian Migratory Bird Agreement (CAMBA); Japanese-Australian Migratory Bird Agreement (JAMBA); Republic of Korea-Australian Migratory Bird Agreement (ROKAMBA); and Convention on the Conservation of Migratory Species of Wild Animals – Bonn, 1979 (CMS), also known as the Bonn convention. These agreements state each signatory will strive to protect birds listed, conserving or restoring habitat areas, mitigating obstacles and controlling other factors that might impede migration.

Based on the site assessment and desk top study: 15 bird species listed in the international conventions either have been observed or potentially use the wetlands while migrating. Each migratory bird species considered have extensive ranges within the region and each species has a wide distribution of potential habitat throughout the region. Therefore it could be considered no significant area of known habitat for migratory bird species is likely to be removed as a result of the proposed action; Six native fish species were recorded to be present during recent surveys. An additional four native fish species, three threatened and one endangered population, have former distribution within the region; The proposal does have the potential to disturb, remove or modify habitat important to native fish and impact on the movements of native fish. However, due to current drought conditions and as long as both regulators are managed to allow water flow back into the wetland during surplus flows, the direct and indirect impact on the quality of habitat is unlikely to affect the presence of these species in the long term. Short term impacts will see fish species that have not managed to escape the drying wetland to become stranded. As the wetlands are naturally drying, under drought conditions this stranding without barriers potentially would occur naturally; An endangered invertebrate specie has former distribution in the region. This specie with limited dispersal abilities, previously has inhabited river systems as well as irrigation drain pipes in NSW, although was not observed during recent surveys; An endangered amphibian specie has a known distribution in the region. This specie is dependant on both aquatic and terrestrial habitat areas; Distributions of three endangered and 13 vulnerable woodland birds occur within the region and are considered to have an extensive range within the region. Woodland birds can tolerate fluctuating water levels as long as food resources, suitable habitat and alternate water sources are not impacted on; One endangered and four vulnerable waterbirds have distribution within the region.

These wetlands are already suffering forms of degradation due to drought conditions. As no known significant habitat areas are present at these wetlands for these waterbirds, it can be considered no known habitat is likely to be removed as a result of the proposed actions, as long as management considers a re-wetting phase when surplus water flows become available; Two vulnerable plant species, both terrestrial forbs, have been recorded in the region. These species habitat is not related to, or dependant on wetlands; Two endangered and one vulnerable mammal species have been recorded in the region. Mammals may be considered dependant on wetlands as they require access to water, none of these threatened mammals recorded in the region spend their entire life cycle in wetland habitats; The lower Murray River in which these two wetlands occur is listed as an endangered ecological community. Modifications to hydrological regimes within these two wetlands will lead to changes in the structure of the community and potentially result in the loss of species. However, this will be balanced by re-instating a wetting cycle when surplus water is available, this may benefit some species; There is potential for the Inland Grey Box Woodland Endangered Ecological Community (final determination under the TSC Act made on 27th April 2007) and the Buloke Woodlands Ecological Community of the Riverina and Murray-Darling Depression Bioregions (EPBC Act) to occur at these wetlands. These communities’ are characterised by a number of plant species and are important habitat areas for many fauna species. Modification to the hydrological regimes within these two wetlands is unlikely to impact on these communities; The landscape surrounding the wetlands is well represented with forests, nature reserves, rivers and creek systems. Due to widespread drought conditions across most of the State, these areas are suffering various forms of degradation. The drying of wetlands during these drought conditions is likely to add further stress to other wetlands, creeks and rivers, through an increase in abundance of species looking for alternative water sources and habitat. • In both wetlands the risk of sulfidic sediments occurring is low. On re-wetting it is unlikely that either wetland will become acidified It is recommended the following points be considered to minimise disturb