Clutha River catchment Water quality and ecosystem health July 2010 to June 2011 Water Quality Summary Introduction • All but a few sites in the Clutha catchment had good The Otago Regional Council (ORC) monitored 36 river and stream sites in the or very good water quality Clutha catchment between July 2010 and June 2011 to assess the current • The Heriot Burn had the state of water quality. Most sites were monitored bi-monthly, but five further worst quality followed by the sites (Clutha River/Mata-Au at Luggate, Millers Flat, Balclutha, the Kawarau upper Waipahi River River, and the Shotover River) were monitored monthly by NIWA as part of the National River Water Quality Network (NRWQN). Sites were classified • The Dart River had fair using a water quality index. water quality in 2011 due to naturally high sediment Very Good All six values comply with guideline values levels (elevated turbidity) and Good Five median values comply phosphorus Fair Three or four median values comply • Both Didymosphenia Poor Two or fewer median values comply with guideline values geminata and Phormidium were present in the Lindis River • All macroinvertebrate monitoring sites had at least average SQMCI scores • Generally, most fish monitoring sites had at least two species with trout being found at all but one site. Water quality index ORC uses a water quality index (WQI) derived from medians of six indicator variables, turbidity, dissolved oxygen (percent saturation), ammonical nitrogen (NH4), nitrite-nitrate nitrogen (NNN), dissolved reactive phosphorus (DRP) and Escherichia coli (E. coli). Median values of the six values are compared with ANZECC (2000) and MfE/MoH (2003) guidelines, enabling classification of water quality into one of the four groups. 1 Clutha River catchment February 2012 Clutha River catchment.indd 1 14/02/2012 4:04:07 p.m. Clutha River catchment.indd 2 Clutha Rivercatchment 2 Mill Creek instream values. of effects-basedstandardsfor a proposaltointroduceseries is currentlyunderreviewwith The OtagoRegionalPlan:Water ANZECC guidelinevalue. the graphs)depictrelevant The horizontallinesinred(in effects areconsideredlow. the risksofadversebiological values specifyalevelbelowwhich m abovesealevel).Thetrigger water courses(lessthan150 outline triggervaluesforlowland The ANZECC(2000)guidelines nutrients Guidelines for Waipahi River Waipahi River Waiwera February 2012 Burn hadthehighestNNNconcentration. farming ordairyiscommonplace,asaretiledrains.TheHeriot of NNNinsouth/south-westOtagoarewherehighintensitysheep farming ordominatedbytussocklands.Thehighestconcentrations Otago andtheCluthaLakes,whereland-useislow-intensitysheep growth. MostofthesiteswithlowNNNconcentrationsareinCentral from landdrainage.Itisanimportantnutrientforalgaeandplant Nitrite-nitrate nitrogen(NNN)isaformofprimarilyderived Nutrients Lake Dunstan. concentrations, suchastheManuherikiaatOphir,LuggateCreek,and DRP concentration.SeveralsitesinCentralOtagoalsohadhigh south-west OtagowiththeWaiweraRiverrecordinghighest exceeding theANZECCguideline.Severalsiteswereinsouth/ shows thatabouthalfofthesitessampledhadDRPconcentrations wastewater effluent,animalandfertiliser.Thegraphbelow Sources ofDRPcanbetracedbacktopointsourcedischarges Dissolved reactivephosphorus(DRP)isagrowth-limitingnutrient. DRP (mg/l) 0.5 NNN (mg/l) 1.5 0.035 0.005 0.015 0.025 0 2 1 0.01 0.02 0.03 0 Dart River Dart River Lake Wakatipu Lake Wakatipu Matukituki River Matukituki River Lake Wanaka Lake Wanaka Lake Hawea Lake Hawea Nevis River Nevis River Hawea River Hawea River Mill Creek Mill Creek Lake Hayes Lake Hayes Hayes Creek Hayes Creek Arrow River Arrow River Lake Johnson Lake Johnson Cardrona River Cardrona River Luggate Creek Luggate Creek Clutha at Luggate Clutha at Luggate Upper Lindis River Upper Lindis River Lower Lindis River Lower Lindis River Lake Dunstan Lake Dunstan Shotover River Shotover River Kawarau River Kawarau River Manuherikia at Galloway Manuherikia at Galloway Dunstan Creek Dunstan Creek Manuherikia at Ophir Manuherikia at Ophir Fraser River Fraser River Lake Onslow Lake Onslow Tima Burn Tima Burn Minzion Burn Minzion Burn Teviot Burn Teviot Burn Clutha at Millers Flat Clutha at Millers Flat Tuapeka at Tuapeka Tuapeka at Tuapeka Upper Waipahi River Mouth Upper Waipahi River Mouth Lower Waipahi River Lower Waipahi River Heriot Burn Heriot Burn 14/02/2012 4:04:08 p.m. Pomahaka at Burkes Ford Pomahaka at Burkes Ford Waiwera River Waiwera River Waitahuna River Waitahuna River Lake Tuakitoto Lake Tuakitoto Clutha at Balclutha Clutha at Balclutha Clutha River catchment.indd 3 Dart Glacier.Assuchittransportshighvolumesofglacialtill. NTU. TheDartRiverhasnaturallyhighturbiditylevelsasitdrainsthe highest turbidityconcentrationswithamedianconcentrationof40.8 some sitesinSouthOtagoandtheDartRiver.TheRiverhad Turbidity concentrationswerelowforthemajorityofsitesexcept Turbidity cfu/100 mlonallsamplingoccasions. guideline. HeriotBurnexceededthesinglesampledguidelineof260 Central Otagosites(TimaBurnandMinzioBurn)alsoexceededthe median concentrationof where intensivefarmingisdominant.TheHeriotBurnrecordeda where theguidelinewasexceededwereinsouth/south-westOtago guideline of126cfu/100mlatseventhesites.Mostsites Median concentrationsof Bacteria Turbidity (NTU) E. coli (cfu/100 ml) 1000 1200 1400 1600 20 30 40 50 10 200 400 600 800 0 0 Dart River Lake Wakatipu Dart River Matukituki River Lake Wakatipu Lake Wanaka Matukituki River Lake Hawea Lake Wanaka Nevis River Lake Hawea Hawea River Nevis River Mill Creek Hawea River Lake Hayes Mill Creek Hayes Creek Lake Hayes Arrow River Hayes Creek Arrow River E. coli Lake Johnson E. coli Cardrona River Lake Johnson Luggate Creek Cardrona River Luggate Creek Clutha at Luggate 12timesthenationalguideline.Some Upper Lindis River Clutha at Luggate wereabovetheANZECC(1992) Lower Lindis River Upper Lindis River Lake Dunstan Lower Lindis River Shotover River Lake Dunstan Kawarau River Shotover River Manuherikia at Galloway Kawarau River Dunstan Creek Manuherikia at Galloway Manuherikia at Ophir Dunstan Creek Fraser River Manuherikia at Ophir Lake Onslow Fraser River Tima Burn Lake Onslow Minzion Burn Tima Burn Teviot Burn Minzion Burn Clutha at Millers Flat Teviot Burn Tuapeka at Tuapeka Clutha at Millers Flat Upper Waipahi River Mouth Tuapeka at Tuapeka Mouth Lower Waipahi River Upper Waipahi River Heriot Burn Lower Waipahi River Pomahaka at Burkes Ford Heriot Burn Pomahaka at Burkes Ford Waiwera River Waiwera River Waitahuna River Waitahuna River Lake Tuakitoto Lake Tuakitoto Clutha at Balclutha Clutha at Balclutha Heriot Burn Asedimentplumeinthe exceed 260cfu/100ml. that asinglesampledoesnot (2003) guidelinerecommends Ministry fortheEnvironment The MinistryofHealthand units)/100 ml. less than126cfu(colonyforming recommend aseasonmedianof The ANZECC(1992)guidelines Guidelines forbacteria (Nephelometric turbidity units). turbidity islessthan5.6NTU The ANZECCguidelinevaluefor poor fishspawningconditions. to smotherbedhabitat,creating High sedimentloadingalsotends reducing basalfoodsupplies. to photosynthesise,therefore ability macrophyte andalgae’s penetration impactingon turbidity canreducelight sediment loads.Havinghigh often havehighsuspended bed. Streamswithhighturbidity the watercolumntoriver much lightisabletopenetrate Turbidity isameasureofhow turbidity Guidelines for Cardrona River Clutha Rivercatchment February 2012 14/02/2012 4:04:08 p.m. 3 Ecosystem health Algae (Periphyton) Ecosystem health takes into Excessive amounts of periphyton, in particular, filamentous algae, can account a wide range of inter- reduce the amenity value of waterways by decreasing their aesthetic linked factors such as water appearance, reducing visibility, and being a physical nuisance to quality, habitat and instream swimmers. While algae is a useful tool for monitoring the nutrient biota. It is generally assessed conditions in rivers and streams, it is just one method used to get a using two communities that complete overview of the river system. Factors other than nutrient are important to the food levels also influence the composition of benthic algal communities. chain in rivers: streambed These include substrate composition, river flows, the amount of light macroinvertebrates (e.g. insects, reaching the river bed, and water temperature. crustaceans, snails and worms) Algal samples were collected from 12 sites. Algae were given an and periphyton (e.g. algae). Biotic abundance score ranging from 1 (rare) to 8 (dominant) based on the indices are used to summarise a protocols developed by Biggs and Kilroy (2000). All abundance scores large amount of information into were totalled for each algae type (graph below) to give an appreciation a compact and simple form. They of relative abundance. are therefore, inherently coarse tools that give a broad view All sites were dominated by diatom communities with Luggate Creek of general patterns. However, having the most dominant diatom community. The Heriot Burn had they are useful as the presence, the least dominance of any algal types while the Waitahuna River abundance, or distribution of was equally dominated by filamentous red algae, cyanobacteria, species can inform us greatly and diatoms. Didymo was only present in the Lindis River, while about the quality and condition Phormidium was only present in the Cardrona and Lindis Rivers. The of the river in which they live. Heriot Burn’s low algae scores (despite high nutrients) could reflect the fine sediment on the stream bed providing an unstable surface to Biggs,