North and Coastal Otago Summary Report July 08 - June 09
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North and Coastal Otago Summary Report July 08 - June 09 Contents Water quality monitoring Water Quality Results • Nutrients Between July 2008 and June 2009, the Otago Regional Council • Bacteria (ORC) monitored 19 river and stream sites in the northern and • Dissolved oxygen coastal areas of Otago to assess the current state of water quality. Ecosystem Health • Macroinvertebrate health Most sites were monitored bimonthly. • Algae • Fish Sites were classified using a water quality index, and the results are River Flows shown in the map below. The water quality index is derived from median values of six indicator variables: turbidity, dissolved oxygen (% saturation), ammoniacal nitrogen, nitrite-nitrate nitrogen, dissolved reactive phosphorus, and Escherichia coli (E.coli) bacteria. Median values of these variables were compared with ANZECC and MfE/MoH guideline levels, enabling classification of water quality into one of the following groups: Very All seven values comply Good with guideline values Five or six median values comply (to Good include dissolved oxygen) Three or four median values comply (to Fair include dissolved oxygen) Two or fewer median Poor values comply with guideline values Discharges to streams and rivers in North and Coastal Otago comprise of point sources such as treated sewage and industrial discharges. However, land use has the greatest effect on water quality and the sites with poorer water quality include urban sites such as Dunedin city streams as well as streams in intensively farmed catchments such as Waiareka Creek. North and Coastal Otago Summary Report July 08 - June 09 Key Points Water quality results • Two sites were classified as poor in Selected water quality indicators are displayed in the graphs and discussed below. 2008. This was due to low dissolved Overall, these graphs show that water quality is generally good or very good, but oxygen levels in Waiareka Creek and with poorer quality in Dunedin’s urban streams. Trotters Creek. Nutrients • The Kakanui River had much higher Nitrite-nitrate nitrogen (NNN) is a form of nitrogen primarily derived from land levels of E. coli bacteria than in drainage. It is an important nutrient for algae and other plant growth, but can 2007. be harmful in higher concentrations. Three of the five Dunedin urban stream sites monitored exceeded the ANZECC trigger value, as did the Shag River at the • Dunedin’s urban streams had high Goodwood water intake and Welcome Creek. Welcome Creek is spring fed and concentrations of nutrients and the concentrations of NNN in the groundwater are high. The remainder of sites bacteria. had median values well below the default trigger. • The Owaka River had the highest concentrations of NNN and TN. Nitrite/Nitrate Nitrogen g/m3-N ANZECC 2000 Guideline It also had concentrations of bacteria and phosphorus above guideline 1.8 1.6 levels. 1.4 1.2 1 • Northern Otago coastal rivers 0.8 0.6 showed better water quality than 0.4 both Dunedin’s urban streams and 0.2 0 South Otago’s rivers. Catlins River Catlins • There is a reasonable correlation d/s Kaikorai Trotters Creek Trotters Lindsays Creek Lindsays Waiareka Creek Waiareka Kauru at Ewings at Kauru Shag at Craig Rd Craig at Shag Welcome Creek Creek Welcome Waikouaiti River Waikouaiti Kaikorai mid site midKaikorai Nitrite/Nitrate Nitrogen g/m3-N ANZECC River d/s Waitati 2000 Guideline Kakanui at at Clifton Kakanui Tokomairiro W Br W Tokomairiro between water quality and biological Water of Leith u/s of Leith Water d/s of Leith Water Waianakarua River Waianakarua Shag at Goodwood at Shag Careys Creek SH1 at Creek Careys Kakanui at at McCones Kakanui health. 1.8 1.6 1.4 Guidelines and 1.2 Standards Median1 dissolved reactive phosphorus (DRP) concentrations were above the ANZECC 0.8 Dissolved Reactive Phosphorus g/m3-P ANZECC 2000 Guideline trigger0.6 value at over half of all sites analysed. These high-DRP sites include Welcome 0.140.4 • The ANZECC (2000) guidelines Creek,0.2 Waiareka Creek, Shag River at Goodwood, the Waitati River, Dunedin’s urban 0.120 outline trigger values for water streams0.1 and the Catlins River at Houipapa. Rivers of the north Otago coast generally quality aspects that put stress on showed0.08 median DRP concentrations lower than the trigger value, with the exception of river and stream health. The trigger Waiareka0.06 Creek and Welcome Creek. Catlins River Catlins 0.04 d/s Kaikorai Trotters Creek Trotters Lindsays Creek Lindsays Waiareka Creek Waiareka Kauru at Ewings at Kauru Shag at Craig Rd Craig at Shag Welcome Creek Creek Welcome Waikouaiti River Waikouaiti levels specify a level below which the Kaikorai mid site midKaikorai Waitati River River d/s Waitati Kakanui at at Clifton Kakanui Tokomairiro W Br W Tokomairiro 0.02 u/s of Leith Water d/s of Leith Water Waianakarua River Waianakarua Shag at Goodwood at Shag Careys Creek SH1 at Creek Careys risk of adverse biological effect is 0 at McCones Kakanui low. Note: the ANZECC trigger values Catlins River Catlins Kaikorai d/s d/s Kaikorai used here are for lowland rivers Trotters Creek Trotters Lindsays Creek Lindsays Waiareka Creek Waiareka Kauru at Ewings at Kauru Shag at Craig Rd Craig at Shag Welcome Creek Creek Welcome Waikouaiti River Waikouaiti Kaikorai mid site mid Kaikorai Waitati River River d/s Waitati Kakanui at at Clifton Kakanui Dissolved Reactive Phosphorus g/m3-P ANZECC 2000 Guideline Br W Tokomairiro Water of Leith u/s of Leith Water d/s of Leith Water Waianakarua River Waianakarua Shag at Goodwood at Shag (<150m). Careys Creek Creek at SH1Careys Kakanui at at McCones Kakanui 0.14 • Otago’s water quality standards 0.12 0.1 are outlined in the Regional Plan: 0.08 Water (Water Plan), which sets 0.06 targets to maintain and improve 0.04 0.02 water quality within the region. 0 • The ANZECC (1992) guidelines for contact recreation waters recommend Catlins River Catlins Kaikorai d/s d/s Kaikorai Trotters Creek Trotters Lindsays Creek Lindsays Waiareka Creek Waiareka Kauru at Ewings at Kauru Shag at Craig Rd Craig at Shag Welcome Creek Creek Welcome Waikouaiti River Waikouaiti Kaikorai mid site mid Kaikorai Waitati River River d/s Waitati a season median of less than 126 Kakanui at at Clifton Kakanui Tokomairiro W Br W Tokomairiro Water of Leith u/s of Leith Water d/s of Leith Water Waianakarua River Waianakarua Shag at Goodwood at Shag Careys Creek Creek at SH1Careys E. coli/100ml. at McCones Kakanui Note: The red lines on these graphs indicate the ANZECC trigger value or the MfE/MoH guideline level. 2 North and Coastal Otago Summary Report July 08 - June 09 Bacteria Median levels of E. coli bacteria were above the MfE/MoH guideline level (126 cfu/100ml) at four of the 19 sites analysed. Levels were highest in Dunedin’s urban streams and the Kakanui River. Welcome Creek just exceeded the guideline level Other Analytes of E. coli. The MfE/MoH contact recreation guideline is 260 cfu/100ml for a single sample. The only sites to breach this level at any time were Carey’s Creek, Water of • Ammoniacal nitrogen is the Leith (upstream) and the Tokomariro West Branch. combination of ammonium ions and ammonia (NH3). Levels of ammoniacal nitrogen were well below the ANZECC guideline level Escherichia coli Type 1 mpn/100ml ANZECC 1992 Guideline of 0.9 mg/l in all samples analysed. 500 450 NH3 is the main toxic component 400 of ammoniacal nitrogen, the 350 300 toxicity of which is dependent on 250 200 pH and temperature. Taking these 150 100 factors into account, levels of NH3 50 0 were also well below the guideline value (0.021 mg/l) at all sites. Escherichia coli Type 1 mpn/100ml ANZECC 1992 Guideline Catlins River Catlins 500 d/s Kaikorai • Turbidity was below trigger values Trotters Creek Trotters Lindsays Creek Lindsays Waiareka Creek Waiareka Kauru at Ewings at Kauru Shag at Craig Rd Craig at Shag Welcome Creek Creek Welcome Waikouaiti River Waikouaiti Kaikorai mid site mid Kaikorai 450 d/s River Waitati Kakanui at at Clifton Kakanui Tokomairiro W Br W Tokomairiro Water of Leith u/s of Leith Water d/s of Leith Water Waianakarua River Waianakarua Shag at Goodwood at Shag at all sites. The highest median 400 SH1 at Creek Careys Kakanui at at McCones Kakanui 350 level (4.1 NTU) was found in the 300 250 Owaka River. 200 150 100 Dissolved50 oxygenDissolved Oxygen (saturation) % RMA 1991 guideline • Six sites had median concentrations Dissolved0 oxygen saturations should be above 80%, as below this level saturation of total nitrogen elevated above 120 the trigger level of 0.614 mg/l: is considered100 insufficient for biological health. The median saturation was above this level80 at all sites. This is a vast improvement from last year when Waiareka Waiareka Creek (0.84 mg/l), Catlins River Catlins Kaikorai d/s d/s Kaikorai Trotters Creek Trotters Creek had a dissolved oxygen saturation of just over 60%, andCreek Lindsays from 2005 when Lindsay’s Creek (0.66 mg/l), the Waiareka Creek Waiareka 60 Ewings at Kauru Shag at Craig Rd Craig at Shag Welcome Creek Creek Welcome Waikouaiti River Waikouaiti Kaikorai mid site mid Kaikorai Waitati River d/s River Waitati Kakanui at at Clifton Kakanui Tokomairiro W Br W Tokomairiro Water of Leith u/s of Leith Water d/s of Leith Water Waianakarua River Waianakarua Shag at Goodwood at Shag Careys Creek SH1 at Creek Careys its saturation40 was only 21%. at McCones Kakanui The improvement is likely to be due to increased flow Water of Leith at Dundas Street from 20the North Otago Irrigation Scheme.