In-River’ Nutrient Loads

What do we currently know? …about ground & surface water quality… & land use… in the Waiau River catchment

Gathering current knowledge with the Science Stakeholder Group: 16 November 2016, Amberley Purpose

• Share what we (the whole SSG) know • Find, & plan to fill, knowledge gaps • Reach a level of comfort with messages

…to inform ZC & wider community Outline topics for today

1. Groundwater quality (20 mins) 2. Surface water quality / ecology (60 mins) 3. Current land use & N loads (20 mins) 4. Next steps… Waiau catchment groundwater quality

Maureen Whalen – Groundwater Science Key messages

• Groundwater quality is good overall • Vulnerable to bacteria impacts • Some wells with elevated nitrate • Note upward nitrate trends in the Culverden Basin • Useful to compare to data from other organisations Groundwater uses in the catchment

Primary use is irrigation and drinking water supply Long-term groundwater quality monitoring wells

• Good spatial coverage • New Emu Plains well • Variable length records (<2 to >20 years) Median E. coli counts

• Groundwater is vulnerable to bacteria impacts Maximum Nitrate-Nitrogen concentrations

• Generally, maximum nitrate concentrations are lower than NZ drinking-water standards • A few wells have sufficient long- term records to determine trends Nitrate-Nitrogen trends (2006 – 2015)

• Most wells have no clear upward or downward trend • Hanmer Plain wells don’t have long enough record to see trends Amuri Plains area well

18 Increasing nitrate trend since 2006, 16 possibly land-use intensification

10 MAV (11.3 mg/l)

0 1995 1997 1999 2001 2003 2005 2007 2009 2011 2013 2015 Parnassus area well (10m) 9

Decreasing trend since 2008, nitrate seems 8 to respond to large recharge events

0 1995 1997 1999 2001 2003 2005 2007 2009 2011 2013 2015 Parnassus area well (22m)

MAV (11.3 mg/l) 10

4 • No increasing or decreasing trend since 2006 • Increasing from 1995 to 2006 2 • Near MAV

0 1995 1997 1999 2001 2003 2005 2007 2009 2011 2013 2015 Phosphorus concentrations (2016)

Hanmer well - May be due to naturally occurring conditions Groundwater quality comparison with NZ drinking water standards Community drinking water supplies – protozoa test results • Protozoa (giardia and cryptosporidium) are not removed by most drinking water treatments (such as MIOX). • Tests for protozoa are done regularly for HDC on: – Amuri community drinking water scheme (Well 6.7m deep connected to Waiau River); – Cheviot community drinking water scheme (Well 13m deep connected to Waiau River). • No protozoa have been detected. Key messages - recap

Adrian Meredith – Principal Surface Water and Ecology Scientist Kimberley Dynes – Ecology Scientist Environment Canterbury • Waiau River (3 sites) 2004-Present • Mason River and Leader River: 2005-Present • Home Stream, Rotherham Stream, Lowry Peaks Drain – monitored by AIC

Home Stream

Rotherham Stream Lowry Peaks Drain Outline of Water Quality Topics • Life supporting capacity – Temperature, DO, sediments • Overall Ecosystem Health • Periphyton – Biomass, cover, green algae, cyanobacteria • Drivers of Periphyton – Nutrients and flow • Swimmability Life-supporting Capacity Water Temperature 2011-12 2012-13 2013-14 2014-15 2015-16 Mason River SH70 20.1 16.9 22.2 25 21.4 Leader River SH1 21.5 19.1 22.9 22.9 20.8 Waiau River Leslie Hills Road15.2 14.3 13.9 17.6 15.2 Waiau River at Waiau 18.3 15.4 18.8 21.1 17.1 Waiau River SH1 18.6 16.9 18.2 23.2 18.1 Dissolved Oxygen (% Sat) 2011-12 2012-13 2013-14 2014-15 2015-16 Mason River SH70 93 97 92 95.8 97.6 Leader River SH1 97.4 91.7 92.4 84.7 96.2 Waiau River Leslie Hills Road 94.5 96.8 95 98.2 98.7 Waiau River at Waiau 95.3 94.5 99.4 94.6 100.9 Waiau River SH1 91.8 94.6 92.4 94 85.9

• Water temperature <20 OC; DO >90% to support aquatic species (particularly salmon and trout)

• Waiau River water temp OK most years • Max water temp exceeds plan objectives in hill-fed rivers • All rivers well oxygenated environments Life-supporting Capacity Sedimentation 2011-12 2012-13 2013-14 2014-15 2015-16 Mason River SH70 15 10 20 90 40 Leader River SH1 15 5 20 30 30 Waiau River Leslie Hills Road 10 80 15 35 50 Waiau River at Waiau 10 5 - 40 15 Waiau River SH1 20 5 10 50 10

• Sediment is a parameter of growing concern • Sediment smothers benthic habitats (20% cover) • Waiau and tributaries can exceed maximum

• More commonly a problem in streams and drains Aquatic Ecosystem Health

• Monitoring of aquatic invertebrate species as an indicator of overall water quality and stream habitat

• QMCI = a grading system based on the relative sensitivity of a species to water quality and habitat degradation. Macro-invertebrates (bugs)

• Macro-invertebrates (>0.5 mm) are the most commonly researched and monitored

EPT

670 species – follow the keys

Plan Minimum 6 Outcome

QMCI 5

2 Waiau River Hanmer Road Hanmer River Hope River SH7 Boyle River SH7 Leslie Hills Road Waiau River SH1 Mason River SH7 Leader River SH1 Mason River SH70 Waiau River at Waiau • All sites except the Leader River at SH1 achieve the minimum plan Objective Key Messages: Aquatic Ecosystem Health

• All sites, except the Leader at SH1 meet the minimum plan objective • Leader River impacted by low flow, sedimentation/embeddedness, nuisance periphyton growth and warm temps • Streams like Lowry Peaks and Rotheram Stream? Periphyton Monitoring • Total Biomass • Total cover %

• Filamentous algae • Cyanobacteria mats • Didymo

• Rivers different susceptability Total Periphyton - biomass • NPS-FM National Objectives Framework – Benthic Periphyton – chlorophyll ‘a’ • indicates benthic periphyton is: – Target <50 mg/m for Waiau River at Leslie Hills – Only have suitable data at 2 sites • Waiau River at Leslie Hills generally good • Mason River variable and not suitable all years

Chlorophylla No. samples National Bottom line CBA SQ34704 Waiau River Leslie Hills 3 yr 36 0 0% 0 0% 1 3% 28 78% 2011-12 12 0 0% 0 0% 1 8% 8 67% 2012-13 12 0 0% 0 0% 0 0% 8 67% 2013-14 12 0 0% 0 0% 0 0% 12 100% SQ34869 Mason River SH70 3 yr 36 2 6% 3 8% 2 6% 22 61% 2011-12 12 2 17% 3 25% 1 8% 3 25% 2012-13 12 0 0% 0 0% 1 8% 10 83% 2013-14 12 0 0% 0 0% 0 0% 9 75% Filamentous Algae periphyton cover Periphyton (long filament) 2011-12 2012-13 2013-14 2014-15 2015-16 Mason River SH70 15 10 30 15 20 Leader River SH1 30 20 45 40 85 Waiau River Leslie Hills Road 0 0 4 1 10 Waiau River at Waiau 0 0 - 2 0 Waiau River SH1 0 0 0 1 2

• elevated green filamentous algae in tributaries

• negligible green filamentous algae in Waiau River

• Different susceptabilities Potentially toxic cyanobacteria (algae) mats in rivers

• Alternative algae growth form: – Black/Brown mats – Potentially toxic to livestock, dogs and people – Odorous and taints food

• May have different drivers to filamentous green algae – Water temperature tolerances – Nutrient concentrations – Nitrogen and Phosphorus  high nitrates, low dissolved phosphorus  Phosphorus sourced from fine sediment – Stable bed, reduced flushing flow frequency, often more common in riffles cyanobacteria mat cover in rivers 80

40 Max % Cover Max Cover % cyanobacteria

0 Mason River SH70 Leader River SH1 Waiau River Leslie Waiau River at Waiau River SH1 Hills Road Waiau

2012-13 2013-14 2014-15 2015-16 Public Health Alert Guideline LWRP Objective/Action Guideline

- Most problematic in Leader River - Present in Waiau River – Highest at upstream site?

- Waiau River may be more susceptible to black mats. cyanobacteria mats in rivers • No public health warnings have been issued

• Leader River exceeded levels but is not a recognized bathing site

• Local observations suggest side braids of Waiau at SH1, and immediately below drains and streams have a denser cover of mats (than the main braid)

• Waiau River more susceptible to mat growth, but flow (floods) currently limits growths Water quality drivers of periphyton

• Targets are periphyton growths and state of the rivers

• Nutrients and water quality measured as a driver of growths

• Not as a target in themselves Nutrients and their impact on water quality • Nutrients – At low concentrations - Beneficial in encouraging thin growths of algae in rivers (food for aquatic life)

– At higher concentrations – encourage conspicuous nuisance growths of algae

– At very high concentrations some nutrients (Nitrate-N, Ammonium-N) can be toxic

• Different guideline address different effects Nutrient impacts on periphyton – Nitrogen

• Increase in nitrogen at SH1 – indicating moderate- high risk of nuisance periphyton blooms 1.2

1.0

0.8 Probability of nuisance growth 0.6

DIN (mg/L) High 100%

0.4

Moderate 70% 0.2

Adequate 50%

0.0 Limiting 30% Waiau River Waiau Leslie Road Hills Leslie Waiau RiverSH1 Waiau Leader River SH1 Leader Mason Mason River SH70 Waiau River Waiau Waiau at Nutrient impacts on periphyton – Phosphorus - Tributaries show moderate increase in risk of nuisance growths - Risk not increasing down the Waiau River 0.045

0.040

0.035

0.030 Probability of nuisance growth 0.025

0.020 High 100% DRP (mg/L)

0.015

0.010 Moderate 70%

0.005 Adequate 50%

Limiting 0.000 30% Waiau River Leslie Hills Road Waiau River SH1 Leader River SH1 Mason River SH70 Waiau River at Waiau Nutrient impacts on periphyton – Phosphorus

• Phosphorus concentrations for all sites indicate potential but not high risk of nuisance periphyton

• Some phosphorus risk at times in hill-fed tributaries – Evidence of increased periphyton growth Key Messages: Nutrients and periphyton in large tributaries

• Nitrogen concentrations adequate • Phosphorus concentrations higher

• Tributaries susceptible to nuisance growths as flows and nutrients more stable

• Tributaries susceptible to growths of both types of algae Key Messages: Nutrients and periphyton in Waiau River • Periphyton risk increasing downstream in Waiau with increase in nitrogen • Phosphorus not high but adequate for periphyton growth

• Waiau River more susceptible to black mats

• Sediment bound nutrients may enhance black mat growth • Drain and small streams may be important. Key Messages: Nutrients and periphyton in drains and streams • Drains and small streams not currently analysed – Hermitage drain, Home Stream, Lowry Peaks Drain and Rotheram Stream

• Nitrogen, phosphorus, and sediment loads may be important for growths in side braids and downstream in the Waiau River

• This component will need more scrutiny of AIC and ECan data Nutrient toxicity – National Criteria • Ammonia and Nitrate toxicity assessed compared to the NPS-FM National Objectives Framework • All river sites monitored classed in the A band of the NPS-FM– indicates no toxicity risk  Mason River SH70  Leader River SH1  Waiau River Leslie Hills Road  Waiau River at Waiau  Waiau River SH1 • spring-fed streams – recent monitoring indicate Nitrate concentrations may have potential low level toxicity effects (on 20% of aquatic species (i.e sensitive species)). More analysis warranted Key Messages: Nutrient Toxicity • Nitrate and Ammonia toxicity for hill and alpine fed rivers does not exceed the A band for NOF • Indicates no toxic effects from nitrate and ammonia • Limited spring-fed stream data indicates potential species loss or growth effects • Does not take into consideration the lower nutrient thresholds for nuisance periphyton Wadeable and Swimmable

• Wadeable = People are exposed to a high risk of infection (>5% risk) from contact with water during activities with partial immersion and some ingestion of water – Annual median must not exceed 1000 MPN/100mL

• Swimmable = moderate risk of infection (< 5% risk) from activities likely to involve full immersion. – Annual 95 th percentile must not exceed 540 MPN/100mL Wadeable and Swimmable

• Wadeable: All sites monitored classed in the A band of the NPS-FM for 2011-16 – indicates suitable for wading activities • Swimmable:  2013-14 3 of 4 sites do not meet minimum requirements for swimmibility  2014-15 - Waiau River SH1 does not meet minimum requirements for Swimmibility  2015-16 – all sites meet the minimum requirements for swimmibility Sites coded red do not meet to minimum acceptable state for Swimmibility for that annum

Swimmable 2011-12 2012-13 2013-14 2014-15 2015-16 Mason River SH70 BB Leader River SH1 INSUFFICIENT BB DATA FOR Waiau River Leslie Hills Road ANALYSIS BAA Waiau River SH1 A Current State of Wadeable and Swimmable (5 years) • Wadeable indicated by median results • Swimmable indicated by 95 th percentile results 2600 2400 2200 2000 1800 1600

1400 NOF Band D 1200 (MPN/100mL) 1000 National Bottom Line

E coliE 800 NOF Band C

600 Minimum acceptable state (Full Immersion Activities) 400 NOF Band B 200 NOF Band A 0 Waiau River Waiau Leslie Hills Road Waiau River Waiau SH1 Leader RiverLeader SH1 Mason RiverMasonSH70 Waiau River Waiau Waiau at Key Messages: Wadeable/Swimmable • All sites meet Wadeable bottom lines and categorised by NOF band A

• Leader River and Waiau River at SH1 do not meet minimum acceptable state for Swimmability

• Suitability for recreation monitoring only carried out for Waiau River at Waiau = insufficient data required to grade site – Preliminary data indicates this site meets Swimmibility requirements Mata Kopae/St Annes Lagoon

Chl a (mg/m3) TN (mg/m3) TP (mg/m3) Mata Kopae/St Annes Lagoon 2014-15 2015-16 2014-15 2015-16 2014-15 2015-16 Median 1.65 85.5 4700 4500 585 1030 Max 65 220

Mata Kopae/St Annes Lagoon Should be below 4. Year 2014-15 2015-16 TLI 6.96 8.02

• Does not meet national bottom lines for phytoplankton or nutrients

• Trophic level index = hypertrophic, indicative of elevated nutrients and highly productive Additional Monitoring Data

Additional monitoring data required or underway:

Plan Monitoring sites – 9 additional tributary sites being monitored for tributary nutrient load determination (plan requirement)

Gap Filling – monitoring commencing of drain and small streams entering the Waiau River

Other data - Source and coordinate with monitoring carried out by other agencies (AIC), particularly on drain and small streams entering the Waiau River Current Gap Filling and Plan Effectiveness monitoring sites Questions? Current land use and estimates of both ‘Source’ & ‘In-river’ nutrient loads

Ned Norton – Technical Lead Ognjen Mojsilovic – Land Resources Scientist How do we estimate current land use patterns at regional scale?

1. Use following databases in GIS… • AgriBase (AsureQuality 2016) Draft • Farm Dairy Effluent consents (ECan 2016) method to • Valuation roll (ECan 2016) be written up & made • Land Cover Database (2012) available • Irrigation (Aqualinc 2015) • Select LINZ Topo 50 layers (LINZ 2016)

2. Match agricultural enterprises to base farm classes established by the MGM project (Matrix of Good Management) Draft result: GIS layer ‘current’ landuse How do we estimate N loss at regional scale?

1. Use estimated current land use GIS layer 2. Use soil layer (MGM classes) 3. Use climate (rainfall) layer (MGM classes) 4. Use N loss estimates (kg/ha/yr) for different farm classes on different soils & rainfall – from the MGM project 5. Use GIS tool to sum up the loads Draft result: GIS layer of N loss Using these layers to estimate DRAFT ‘Source’ loads & compare to ‘In-river’ loads

Catchment Area ‘Source’ loads ‘In-river’ loads (ha) (Nitrogen (Nitrogen tonnes/yr)# tonnes/yr)*

Waiau above Leslie Hills 208,324 565 253; 137; 111

Mason above SH70 20,959 141 35; 1.3; 3.2

Leader above SH1 12,751 131 27; 0.2; 0.3

Waiau (whole catchment above lower 331,879 2201 1666; 984; 1030 recorder)

# Based on summing loads from draft GIS layers on previous slides * Based on annual load estimates for each of years 2013/14 to 2015/16 – see next Variability with ‘In-river’ load calculations DIN annual load DRP annual load estimates (tonnes/yr) estimates (tonnes/ yr) Waiau Leslie Hills 2013-14 253 18 2014-15 137 11 2015-16 111 10 Mason SH70 2013-14 35 4.2 2014-15 1.3 0.1 2015-16 3.2 0.2 Leader SH1 2013-14 27 1.8 2014-15 0.2 0.0 2015-16 0.3 0.0 Waiau Lower - N.B fow and WQ data does not have good site alignment 2013-14 1666 32 2014-15 984 11 2015-16 1030 8

• Loads greatest in 2013-14 • 2014-16 low flows in Mason and Leader Rivers The differences between ‘Source’ loads and ‘In-River’ loads?

1. Methods (modelled vs measured [still estimated] ) 2. Attenuation – uptake between sources & receiving environment 3. Time lags – between source & in-river 4. Assumptions - current versus past & future practices (eg where are we at compared to ‘good management practice defined by MGM project?) Next steps to improve?

1. Current land use patterns – local ground- truthing & adjustment? 2. Local help with assumptions - current versus past & future practices eg where are we at compared to ‘good management practice’ (MGM)? 3. Others? Questions?