Year 2016 STATE OF THE DERWENT Report Card POLLUTION SOURCES, LOADS AND TRENDS

THE DERWENT ESTUARY MANAGEMENT AND ENVIRONMENTAL Pollutants of particular concern in the Pollution enters the Derwent estuary from Effluent reuse turns a waste product into RESTORATION MONITORING AND Derwent estuary include: many sources, commonly referred to as valuable, nutrient-enriched irrigation The Derwent estuary lies at the heart of REPORTING ‘point sources’ and ‘diffuse sources’. Point water, removing nutrients that would the Hobart metropolitan area and is a The Derwent Estuary Program (DEP) • heavy metals, as these may be toxic sources include sewage treatment plants otherwise enter the Derwent estuary. waterway of great natural beauty and was established in 1999 as a partnership A fundamental requirement for to aquatic plants and animals, and and large industries, such as the Norske In 2015, the volume of sewage effluent diversity. Named after the Celtic word to restore and protect the Derwent effective natural resource management accumulate in seafood – a potential Skog paper mill at Boyer and Nyrstar reused increased again, and now ‘clear water’ in 1794, the Derwent is estuary. The program has been is an on-going and reliable source of health risk for local anglers. Hobart zinc smelter at Lutana. accounts for 20% of the regional sewage an integral part of ’s cultural, successful in bringing together a wide environmental data. This principle • excessive nutrients, as these can generated. economic and natural heritage. The range of stakeholders – firstly to build forms the basis of the DEP’s cooperative trigger algal blooms that reduce Diffuse sources include stormwater

estuary is an important and productive a common understanding, vision and monitoring program between the water clarity, smother fish habitat runoff from urban areas as well as the Sewage Effluent Reuse 3500 and deplete oxygen. Low oxygen may larger catchment inputs carried by the Rosny ecosystem and supports a wide range of management framework – and secondly state government, councils, industries 3000

ML Rokeby 2500 habitats and species. to progressively implement this vision and research institutes. Formerly result in fish kills, rotten egg odours Derwent and Jordan rivers. Other diffuse Mac Point 2000 Selfs Point and release of nutrients and heavy pollutant sources include air pollution, 1500 through partnership agreements and independent monitoring programs are Cameron Bay 1000 Green Point

metals from sediments. landfills, aquaculture operations, and Reuse volume in 500 practical actions. now coordinated so as to provide better Brighton 0 information on the estuary as a whole, wastes associated with ports and marinas. 2010/112011/12 2012/132013/142015 The program was initially designed to • pathogens from human sewage that and to report annually on environmental Sediments within the estuary itself may address environmental quality issues such are a human health risk conditions and trends in the Derwent. also release pollutants into the overlying Pathogens – usually measured indirectly as industrial and urban water pollution, • sediments, as these reduce light waters under certain conditions. using faecal indicator bacteria – can be contaminated sediments, invasive species available to aquatic plants derived from overflows or leaks from and loss of estuarine ecosystems. More • litter – particularly floating plastics Industries have historically been the the sewerage network, as well as animal recently, our scope has broadened to main source of heavy metal pollution faeces associated with stormwater and include the catchment and channel to the Derwent, however loads have ESTIMATED COMBINED LOADS rural run-off. Urban stormwater accounts Approximately 43% of Tasmania’s influences, as well as education and declined significantly in recent years. for the majority of sediment and litter population - 221,000 people - live around amenity. Key program areas include Nutrients: dissolved inorganic nitrogen Contaminated groundwater at Nyrstar 700 that enter the Derwent, with unmanaged the estuary’s margins. The Derwent is environmental monitoring and reporting, 600 is now the largest remaining source, 500 Industry erosion from construction sites a widely used for recreation, boating, coordination of regional activities, 400 and is being captured and treated using Sewage particular concern. 300 Stormwater a series of innovative projects. In 2015,

fishing, marine transport and industry. stormwater management, heavy metal tonnes/year 200 River Further upstream, the investigations, wetland and seagrass This ‘Report Card’ summarises monitoring 100 over 90 tonnes of zinc and other metals Catchment and Channel: During 2014 0 supplies the majority of the region’s conservation, and promotion of walking data collected by the DEP and our 2011 2012 2013 2014 2015 were captured, together with nearly all and 2015, a series of taste and odour stormwater run-off. issues in drinking water, together with fish drinking water supply and is a major tracks. partners, as well as other relevant Nutrients: total phosporous 250 kills, and excessive algae growth in the source of hydroelectric power. information collected during 2015 and Groundwater metals recovery The DEP is supported by the Tasmanian 200 160 early 2016, including: Industry upper estuary prompted a collaborative 140 A number of environmental issues affect Government, six councils that border 150 Sewage 120 catchment monitoring program (see 100 Stormwater Cadmium

the Derwent estuary, in particular: on the estuary (Brighton, Clarence, • weekly recreational water quality tonnes/year 100 River Zinc 50 80 box below). In the Channel, the Derwent Valley, Glenorchy, Hobart and testing during summer months 60 tonnes/year • heavy metal contamination 0 40 D’Entrecasteaux and Huon Collaboration, Kingborough Councils) and five business • monthly whole-of-estuary and 2011 2012 2013 2014 2015 • poor recreational water quality at 20 (supported by the DEP), has released their partners (Nyrstar Hobart, Norske Skog catchment water quality monitoring 0 some bays and beaches Zinc 2009/102010/112011/122012/132013/142015 first report card that includes information Boyer, TasWater, TasPorts and Hydro • surveys of heavy metal levels in fish 120 • low oxygen levels in the upper estuary 100 on marine farming, sewage and other Tasmania). Other project partners include and shellfish 80 Sewage Sewage treatment plants are the largest during summer Stormwater 60 nutrient sources. For details, see the Institute of Marine and Antarctic • biological surveys (seagrass, spotted Nystar Outfall source of bioavailable nutrients, followed

• elevated nutrient concentrations tonnes/year 40 Nyrstar Groundwater www.nrmsouth.org.au/dentrecasteaux- Studies, University of Tasmania, CSIRO, handfish) 20 by the catchment, stormwater and the • environmental flows and barriers huon-report-card/ NRM South and BirdLife Tasmania. • weed surveys and control actions (rice 0 Norske Skog paper mill. • introduced marine pests and weeds 2011 2012 2013 2014 2015 grass, karamu) • loss of habitats and species Sediments (as total suspended solids) • impacts of climate change, e.g. sea- More detailed information is published in 35000 Keeping tabs on River Derwent water quality 30000 25000 level rise, erosion and habitat loss five-yearly State of the Derwent Estuary Industry In 2015 a monitoring program was initiated by the DEP, with support from Hydro Tasmania, 20000 Sewage NRM-South and TasWater to monitor nutrients, sediments and other water quality 15000 reports, available on our website: Stormwater

Although there have been significant tonnes/year 10000 indicators in the fresh water portion of the River Derwent above New Norfolk. Water River www.derwentestuary.org.au 5000 improvements in the treatment of sewage samples are collected monthly at 14 sites, including at a number of sites last monitored 0 in 1998. The sites include locations along the River Derwent, between New Norfolk and and industrial wastes over the past 2011 2012 2013 2014 2015 Wayatinah, as well as at the end of major tributaries, such as the Plenty, Styx, Tyenna, decade, the Derwent still faces a number Clyde, Broad, Dee, Ouse and Florentine Rivers. The water quality of the River Derwent in Organic matter (as biochemical oxygen demand) of environmental challenges. A strategic 8000 1998 was excellent however an observed increase in nutrients in the Derwent estuary near and coordinated planning approach Industry New Norfolk, plus the findings of the 2011 River Derwent catchment review, prompted the 5000 Sewage DEP and other organisations to revisit the monitoring program. This monitoring program

across all levels of government, industry tonnes/year will provide baseline information for managing water quality now and in the future, and and the community is our best hope for a may also help explain why we have seen an increase in nutrients in the upper estuary. 0 clean and healthy estuary in the future. 2011 2012 2013 2014 2015

DERWENT WATER AND SEDIMENT QUALITY DERWENT HABITAT AND SPECIES

CLIMATIC CONDITIONS WATER QUALITY Thousands of juvenile barracouta washed HEAVY METALS IN ESTUARINE HABITAT & MARINE PESTS, WEEDS INDICATORS up on the banks of the Derwent estuary SEAFOOD, BIRDS SPECIES AND DISEASE Rainfall in Hobart during 2015 (and the in February 2015 at a time when dissolved summer of 2015/16) was lower than The DEP coordinates a whole-of-estuary Oysters and mussels from the Derwent Surveys of the Derwent estuary indicate The Derwent estuary is extensively oxygen in the salty bottom waters was average, particularly during the spring and monitoring program that integrates contain high levels of heavy metals, that unvegetated, soft-bottom habitats are colonised by introduced marine species. below 20% saturation, compared to summer of 2015/16. River Derwent flows sampling carried out by the DEP and EPA particularly zinc, lead and cadmium. by far the most abundant habitats in the At least 79 invasive species have been a healthy level of greater than 70%. A in 2015 were also low, averaging 19% less Division, Nyrstar Hobart, Norske Skog and While levels appear to have declined estuary (86%), followed by seagrass and recorded, including four species of dissolved oxygen sampling program was than the long-term (1974-2015) average. TasWater. Water quality is monitored each since 2003 in some areas (i.e. above the macrophytes (7%; primarily in the upper particular national concern: northern initiated to better understand this situation month at 27 sites for indicators such as Tasman Bridge), they are still far in excess estuary), tidal sandflats (6%; primarily Pacific seastar, European green crab, and will continue in 2016/17 to identify SWIMMING IN THE temperature, salinity, dissolved oxygen, of national food standards. in Ralphs Bay) and rocky reefs (1%; Japanese seaweed, and European clam. the drivers of seasonal oxygen levels, with DERWENT suspended solids, nutrients, organic primarily in the lower estuary). A number of other species (e.g. New a focus on river flow dynamics, nutrient Mercury levels exceed national food carbon, chlorophyll a and heavy metals. Zealand half crab, New Zealand seastar, Each summer recreational water quality concentrations and algal cover. standards in several species of Derwent- This information is used to document and New Zealand screw shell) also pose is monitored at about 30 beaches and caught fish – particularly black bream – conditions and trends over time and to a significant threat to the ecology of the bays around the estuary through a and to a lesser degree flathead and trout. provide data for estuarine modelling and estuary. collaborative State and Local Government Limited sampling suggests that levels are process studies. program. Sampling is conducted weekly lower in other recreationally-targeted fish Rice grass – an invasive intertidal weed from December through March at the Dissolved oxygen levels in the Derwent (e.g. whiting, Australian salmon, mullet, – has been successfully managed in the locations shown on the map overleaf. are generally high except periodically in cod and flounder). Derwent through annual surveys and To describe the risk level to swimmers a the area between Bridgewater and New Detailed surveys of nine Derwent control actions, and the area of infestation colour coded system is used based on five Norfolk. During summer months when estuary spotted handfish colonies were had been reduced from two hectares in years of monitoring data: green indicates water temperatures are high and river carried out in 2015, with varied results 1995 to zero in 2009 and 2010. However good, yellow indicates fair, and red flows are low, the deeper channels in CONTAMINATED (Wong, 2015). In particular, the number recent surveys found several small patches indicates poor water quality. this area tend to be oxygen poor, with SEDIMENTS of handfish at the Battery Point site in the middle estuary region. These will adverse impacts on bottom-dwelling appeared to be stable or increasing, continue to be monitored and treated. Eleven of the Derwent’s 18 swimming organisms and some species of fish. Low Levels of heavy metals in Derwent estuary while numbers at Sandy Bay may have sites are currently classified as having oxygen levels can also result in the release sediments are among the highest in declined. Numbers of juvenile fish at all good water quality, six are fair and one of nutrients and heavy metals from . Derwent sediments tend to sites are critically low, and over 2000 is poor. The best water quality sites are underlying sediments. be fine-grained and organic-rich and artificial spawning substrates have been at Hinsby, New Norfolk, Blackmans Bay Based on the most recent (2014) 2015 Dissolved oxygen levels at New Norfolk (at depth) significantly exceed national sediment planted out at key sites to improve (middle), and Little Howrah. The western 16 monitoring results for flathead, oysters 14 quality guidelines for zinc, copper, breeding success. Further surveys are

end of Nutgrove Beach received a poor 12 and mussels, there has been no change mercury, lead, cadmium and arsenic. being carried out in 2016 by CSIRO to rating. Of the 21 bays, coves and other 10 in current health advice, which is as 8 The most recent survey (2012) confirmed better understand population dynamics

sites monitored, nine have good water 6 follows: that metal levels are highest in the mid and target management actions 4 quality, six are fair and six are poor (in in mg/L oxygen Dissolved 2 estuary and at depth, with some slight • Don’t eat shellfish collected from accordingly. particular the mouth of 0 Pacific Oyster Mortality Syndrome (POMS) improvements observed in a few areas. the Derwent (including Ralphs Bay) and Browns River, Cornelian Bay and was reported in Tasmania in January 2016, 01/01/15 20/02/15 11/04/15 31/05/15 20/07/15 08/09/15 28/10/15 17/12/15 • Don’t eat any bream from the Marieville Esplanade). with devastating effects on the shellfish Derwent (including Browns River) industry. The DEP, in collaboration with Water quality improved at a number of Nutrient risks to aquatic plants • Limit consumption of other IMAS, surveyed the condition of oyster sites in 2015-16. This is encouraging, but The extensive meadows of aquatic plants in the upper Derwent estuary are vulnerable to rapid Derwent-caught fish to no beds around the Derwent in early March, should be taken in the context of the environmental changes resulting from human population pressure. These plants provide key more than 2 meals/week, or 1 with a particular focus on the proportion very low rainfall experienced over the ecological services including nutrient removal, sediment stabilisation, as well as food and habitat meal/week for pregnant and of dead oysters at each site. The sites with past two summers; a wet summer could for birds, fish and crabs. Aquatic plants are indicators of how ecosystems are tolerating changes breastfeeding women, women the highest numbers of dead oysters were easily reverse these improvements. It is in anthropogenic influences and extensive losses are occurring both in Australia and throughout planning to become pregnant and A pilot study of heavy metal levels generally in the middle estuary (10 to 30% recommended that sanitary investigations the world. The principal factors restricting the health of this habitat are light, temperature, young children Derwent estuary birds revealed high mortality), with lower mortality rates at continue to identify and correct sources of nutrients and salinity. mercury levels in the feathers of sea lower estuary sites. It appears that POMS faecal contamination. Although all plants require some amount of nutrients, algae is quicker to respond to elevated eagles and cormorants, elevated levels may have persisted through the winter, Most urban areas experience poor nutrients than the longer-lived and slower growing aquatic plants, and can grow so densely that NO BREAM NO SHELLFISH in penguins and oystercatchers, and and additional surveys are planned. water quality after heavy rain. the underlying seagrass cannot get enough light to survive or reproduce. In many estuaries this relatively low levels in swans, ducks and Swimming is not recommended in process has resulted in losses of thousands of hectares of highly productive habitat. Dense algal gulls. More research is needed across the Derwent for several days after blooms have recently occurred in the upper Derwent estuary and work is continuing in 2016 to a broader range of species to fully heavy rain and never in the vicinity of better understand the tolerance of aquatic plants to algal smothering in the hope that we can understand the extent of contamination stormwater drains or urban rivulets. determine the conditions needed to protect and enhance this critical habitat into the future. and the species at risk. RECENT MANAGEMENT ACTIONS, Program partners: SAMPLING SITES AND DISCHARGE POINTS

River Brighton

New New Norfolk Bridgewater Norfolk Norske Skog Paper Bridgewater Causeway

Jordan Bridgewater KARAMU CONTROL IN UPPER WETLANDS Karamu, a small tree originating from New Zealand, has invaded the river banks and wetland areas of the upper Derwent near New Norfolk. Over the past five years the DEP in cooperation with other stakeholders have reduced the distribution of this highly invasive weed by poisoning plants at the edge of the infestation and squeezing it towards a central patch from Lawitta to New Norfolk. The management of karamu has been successful because of the cooperation of so many people and organisations. The DEP, Crown Land Services and the Department of State Growth employed HEAVY METAL AT MONA contractors to tackle outlying infestations and conduct treatment trials aimed at defining the best method of controlling karamu. Derwent Catchment In 2012, Kirsha Kaechele, curator at MONA launched Derwent Heavy Metal – a NRM, NRM South and Derwent Valley Council supported Green Army teams to remove karamu and revegetate council parks with native species. By collaboration between artists, architects and scientists to identify ways of raising ‘bookending’ the karamu it is hoped that its management will be reduced to the maintenance of regrowth in the not so distant future. awareness and seeking possible solutions to ridding the river of its heavy metals. To Austins date, Heavy Metal has engaged with more than 60 scientists, artists and architects Ferry from Tasmanian, Australia and the wider world. Partners with MONA include the Derwent River Catchment DEP, University of Tasmania (Institute of Marine and Antarctic Science and Tasmanian College of the Arts), CSIRO and Monash Art Design and Architecture. Projects have Old Beach included symposia, art and architectural installations, swimming events, death metal and summer market stalls. This year MONA awarded six scholarships to science and arts students for Derwent-related projects. The science students were matched Claremont with art students to look at ways of presenting and interpreting their work. Projects include heavy metal uptake in oysters, a GIS project on Pacific Oyster Mortality National Agriculture Parks Syndrome (POMS), innovative treatment trials of mining wastes, metals in penguin feathers, biological settlement plates and a Derwent jazz suite. Dogshear Point Fish Farming Cameron R E V I R Agriculture Bay

STORMWATER CAPTURE AND Logging WASTEWATER REUSE AT NYRSTAR In 2014, the final stages of the Loogana-Inshallah contaminated site rehabilitation were completed, with Bowen commissioning of the Nyrstar Hobart Stormwater Bridge Water Treatment Plant Harvesting and Reuse Project. This included construction of a 40 ML stormwater detention dam, additional DEP SPONSORS CIRQUE TO SEA groundwater interception, capping and revegetation. The East Area 4 Upper Estuary project was awarded the 2014 Tasmanian Engineering GLENORCHY EXPEDITION CLASS Risdon Excellence Award (Environment Category). In 2015, Prince Of Wales Bay The Bookend Trust and the DEP joined forces to share Nyrstar completed the design and construction of a their love of science and environmental education with reverse osmosis (RO) plant, with funding support from Nyrstar classrooms everywhere through Bookend’s Expedition the Australian government. The RO process provides Hobart Smelter Class. The major Expedition Class project for K-6 students Factory Catchment runoff Septic an additional treatment step for the wastewater that is in 2016 was a high country and river adventure. In August Wetlands runoff currently treated by the site’s Effluent Treatment Plant. Moonah Andrew Hughes, expedition leader, set out into the AY Stormwater Sewage The current process treats the site’s wastewater to a Tasmanian wilderness near Lake St Clair. Andrew made outfalls outfall Industrial standard that allows the treated water to be released to Selfs Point his way by foot to one of Tasmania’s highest mountain effluent Swimming Mudflats Recreational fishing TER CAUSEW the Derwent. However, the extra treatment step provided (outfall at Sandy Bay) peaks and then followed the Derwent by pack raft then Hydraulic Water sports Swimming links by the RO Plant will allow the water to be reused on site. New Town Lindisfarne kayak, once the trickle turned into the powerful River NEW NORFOL K

BRIDGE WA Hence the project also involved identification of on‐site Derwent. He traversed the length of the river as it made INPUTS Freshwater Cornelian River Plankton and • sediment flow Resident and natural bacteria uses for the treated water and the installation of a treated its way down to Hobart and then out into the salt water of • litter migratory fish Exchange with Bay • nutrients mid estuary the Southern Ocean. Over 3000 students were engaged • oil Seagrass water pipe system across the site. The benefits of this (modified) • heavy metals • faecal bacteria Seawater project to the environment are clear – reduced volume of with Expedition Class and teachers had free access to Fresh river water treated wastewater to the river, as well as reduced potable the Australian Curriculum based lessons created for this mixing Salt water Microscopic sediment Area Tasman water algae and natural bacteria 4 water use on site. project. The DEP team and a number of our partners were • nutrients 3 HOBART Bridge • organic matter cycling also available during the expedition to answer children’s • heavy metals Oxygen depletion sediment Bottom 2 1 Macquarie Sulpherous gas dwelling questions about the issues and challenges facing river Sludge and organic organisms Poin t rich sediments Rosny catchments. www.expeditionclass.com.au

STATE of the Bellerive Area 3 Middle Estuary STATE DERWENT ESTUARY T N E W R E D 2015 DERWENT ESTUARY 2015 ESTUARY of the DERWENT

Residential Sandy Sewage Howrah Factory treatment Bay plant Oil Wetlands and Catchment tanks mudflats Recreational runoff fishing A review of environmental data from 2009 to 2014 AY

Stormwater TER CAUSEW outfalls Rowing Boating SMAN BRIDGE TA Sandy Bay BRIDGE WA STATE OF THE DERWENT REPORT 2015 Fresh INPUTS Exchange with (outfall from Tranmere water Algal bloom Oil lower estuary Hobart is a capital city that boasts swimmable beaches, an mixing • sediment Selfs Point) • litter Plankton Underwater Salt water • nutrients and natural sewage and extensive network of walking and cycling tracks and great • oil bacteria industrial • heavy metals outfalls opportunities for boating and fishing. A major report looking • faecal bacteria Seawater Rokeby at the health of the Derwent over the past five years has found Seagrass Shellfish and bottom dwelling water Marine pests Area organisms the condition of the estuary has improved in some areas and cycling Sludge and 4 Rokeby organic rich Heavy metal 3 declined in others. This report highlights areas we can work on to sediment sediments deposits • nutrients 2 1 • organic matter Microscopic maintain the health of this highly valued waterway. The State of • heavy metals sediment algae and the Derwent report summarises trends in industrial, sewage and Taroona natural bacteria Lauderdale stormwater discharges, monitoring results for swimming beaches, heavy metal levels in sediments and seafood, and the condition of Area 2 Lower Estuary key habitats and species. The report also highlights actions taken to clean-up the Derwent during this time. Find it at www.derwentestuary.org.au or contact us for a hard copy.

Garden waste, fertilizers, sediment Sewage Roads, land clearing, deforestation, treatment NO Beach sediment loss plant SWIMMING Kingston Stormwater drain Oil Swimming Oil

Stormwater outfalls Recreational

SMAN BRIDGE Ballast & commercial Oil Ralphs Bay

TA water Boating fishing

Mid estuary INPUTS exchange Plankton • sediment Underwater Oceanic Blackmans and natural • litter sewage exchange bacteria • nutrients outfalls • oil Bay • heavy metals Seagrass Kelp and Endangered • faecal bacteria other species seaweed Opossum Microscopic sediment algae and Marine pests Area natural bacteria Shellfish and water 4 Bay bottom dwelling 3 cycling organisms Heavy metal Rocky reef deposits sediment habitat 2 1 • nutrients Blackmans Bay • organic matter • heavy metals

Area 1 Ralphs Bay

WATER QUALITY MONITORING SITES IN 2015 RALPHS NORTH Beach monitoring site (eneooi) Sewage Good water quality treatment plant Catchment runoff Fair water quality Septic Tip site runoff Wetlands and BAY Poor water quality saltmarsWESTh Oil Tinderbox Ambient moitoring site (temperature, salinity, pH, N dissolved oxygen, nutrients, chlorophyll a, metals)

Recreational BAY 04 Stormwater fishing SEWAGE TREATMENT PLANT DISCHARGES IN 2015 Sailboarding outfall kilometres South < 1000 kL/d INPUTS Mudflats Arm 1000 - 5000 kL/d • sediment Plankton • litter and natural Exchange Microscopic sediment algae • nutrients bacteria > 5000 kL/d with and natural bacteria • oil estuary • heavy metals Shellfish and bottom • faecal bacteria dwelling organisms INDUSTRIAL DISCHARGES IN 2015 Area Heavy metal deposits 4 > 50 000 kL/d water 3 cycling Marine pests sediment 2 1 Iron Pot • nutrients • organic matter • heavy metals Betsey Island www.tasmap.tas.gov.au 11124BL