The current water quality state of lakes in the Waitaki catchment

Report No. R15/157 ISBN 978-0-2947507-30-5(print) 978-0-2947507-31-2 (web) 978-0-2947507-32-9 (cd)

Graeme Clarke

December 2015

Report No. R15/157 ISBN 978-0-2947507-30-5(print) 978-0-2947507-31-2 (web) 978-0-2947507-32-9 (cd)

PO Box 345 8140 Phone (03) 365 3828 Fax (03) 365 3194

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Website: www.ecan.govt.nz Customer Services Phone 0800 324 636

The current water quality state of lakes in the Waitaki catchment

Executive Summary

Background Environment Canterbury is working with the Upper Waitaki Zone Committee and the local community to set nutrient load limits for the upper Waitaki catchment. Understanding the current ecological and trophic state of lakes in the catchment is a critical first step in determining appropriate nutrient limits to protect values associated with these lakes.

The problem Land use intensification frequently results in increased loss of nutrients to rivers, groundwater, and lakes. This can result in water quality degradation. Lakes are especially sensitive to nutrient enrichment because they frequently cycle nutrients internally, and act as a nutrient sink. Resulting phytoplankton and macrophyte growth can affect lake ecosystems, water clarity and aesthetic and recreation values. Many of the lakes in the Upper Waitaki catchment are highly valued for their recreation and aesthetic values. This conflict can be resolved by setting nutrient load limits for the lakes, which provides a degree of certainty for lake managers and land owners that desired lake outcomes will be met, while potentially allowing a degree of land use intensification.

What we did We collected data and information primarily from the Environment Canterbury database and the National Institute of Water and Atmospheric Research (NIWA), and calculated lake Trophic Level Index (TLI) scores for all lakes. We compared TLI scores, LakeSPI scores and contact recreation grades to current regional objectives for these lakes.

What we found Most lakes in the Upper Waitaki catchment meet current planning objectives. Lakes Alexandrina, McGregor and Middleton regularly fail to meet objectives related to lake trophic state (TLI). Lakes Tekapo/Takapō, Benmore and McGregor failed to meet objectives related to ecological health, which was assessed using the LakeSPI macrophyte community monitoring tool. While /Takapō failed to meet this objective, it is likely the macrophyte community is in a state close to a historical reference condition. All sites except Loch Laird at Lake Alexandrina were suitable for contact recreation.

What does it mean? Most lakes in the Upper Waitaki catchment have not been significantly adversely affected by land use development in the catchment, and they still retain the values that make them an important part of the Upper Waitaki catchment. The large glacial lakes especially (Tekapo/Takapō, Pūkaki, Ōhau) have very little phytoplankton production, and are all classified as microtrophic. It is also clear that some lakes not buffered by large clean inflows have been impacted by land use intensification. Careful management of further land use development will be required to ensure these impacts are not realised more widely or significantly.

Environment Canterbury Technical Report i The current water quality state of lakes in the Waitaki catchment

ii Environment Canterbury Technical Report The current water quality state of lakes in the Waitaki catchment

Table of contents

Executive Summary ...... i

1 Introduction ...... 1 1.1 Trophic Level Index ...... 1 1.2 Lake SPI ...... 2 1.3 Suitability for Recreation Grade (SFRG) ...... 2

2 Method ...... 3 2.1 Data sources ...... 3 2.2 Lake sampling method ...... 4 2.3 Trophic Level Index calculations ...... 4 2.3.1 Variation in TLI estimates between NIWA and Environment Canterbury...... 4 2.4 Monitoring sites ...... 6 2.5 Assessment method ...... 7

3 Results ...... 8

3.1 Trophic Level Index (TLI3) ...... 8 3.2 Lake SPI ...... 10 3.3 Contact recreation grade (Suitability for Recreation Grade - SFRG) ...... 10

4 Case studies...... 12 4.1 Lake Alexandrina ...... 12 4.2 Kellands Pond ...... 13

5 Discussion and conclusions ...... 14

6 Acknowledgements ...... 16

7 References ...... 16

Appendix 1: Physical characteristics of a number of Upper Waitaki lakes ...... 19

Appendix 2: All Environment Canterbury TLI results for lakes in the Waitaki catchment ...... 20

Appendix 3: All NIWA TLI results for lakes in the Waitaki catchment ...... 22

Appendix 4: All LakeSPI results for lakes in the catchment ...... 23

Environment Canterbury Technical Report iii The current water quality state of lakes in the Waitaki catchment

List of Figures

Figure 1-1: Visual display of extracted chlorophyll at various concentrations (μg/L) ...... 2 Figure 4-1: Lake Alexandrina ...... 12 Figure 4-2: Kellands Pond and surrounding water bodies ...... 13 Figure 4-3: Nitrate and nitrite nitrogen concentrations in Kellands Pond 2004-2013...... 14 Figure 5-1: Recorded flow volume in the at SH8 July. 2013 – June 2014 ...... 15

List of Tables

Table 1-1: Lake types, trophic levels and values of the four key variables that define the different lake types ...... 1 Table 1-2: Suitability for recreation grade (SFRG) matrix for freshwater and marine sites ...... 3 Table 2-1: Sites included in Environment Canterbury’s monitoring programs ...... 6 Table 2-2: Freshwater lake outcomes for lake management units found in the Upper Waitaki catchment ...... 7 Table 3-1: TLI results in high country lakes from 2009. Results from Environment Canterbury’s high country lakes monitoring program ...... 8 Table 3-2: Average TLI result between 2009/10 and 2013/14 (five years)...... 9 Table 3-3: Waitaki catchment LakeSPI results ...... 10 Table 3-4: Lake contact recreation site results and since November 2008 ...... 11 Table 4-1: Trends in nitrate and nitrite nitrogen and turbidity in Kellands Pond from 2004 - 2013 .. 14

iv Environment Canterbury Technical Report The current water quality state of lakes in the Waitaki catchment

1 Introduction This report aims to describe the current water quality status of the lakes in the upper Waitaki catchment. Although many of these lakes are artificial, or have been enlarged through the development of the hydro-electric power scheme, they have become an integral part of the / Upper Waitaki landscape. This report compares the current state of a number of lakes with the water quality objectives for lakes outlined in the proposed Canterbury Land and Water Regional Plan (pLWRP), with the broad aim of informing decision makers setting nutrient limits for these lakes through the pLWRP sub-regional planning process. Lake values can be negatively impacted by increased nutrient loads, and understanding current trophic status and ecological health is a key step in making decisions regarding maintenance of particular values. Several key indicators of lake health have been used in this report. They are:

1.1 Trophic Level Index The Trophic Level Index (TLI) is an indicator of lake water quality specifically developed for NZ lakes by Burns et al. (1999). The index is derived from four water quality measures including total nitrogen, total phosphorus, chlorophyll A (found in algae), and Secchi disc water clarity measurements. Higher values indicate greater nutrient enrichment, more algal biomass (Table 1-1 and Figure 1-1) and lower water clarity. It is widely used throughout and has been adopted by the Ministry for the Environment as the national indicator of lake water quality status. A number of similar indexes are used internationally. For example, Carlson's Trophic State Index (Carlson, 1977) and the Chapra and Dobson Index (Chapra and Dobson, 1981) are both used in North America and based on similar water quality indicator components (i.e., TN, TP, etc) For some lakes the inclusion of the Secchi depth component score in the calculation of TLI is omitted. This can include lakes that are affected by natural glacial sources that can affect water transparency, or shallow lakes that are prone to wind-driven resuspension of lake sediments. In these instances the TLI score can be calculated with just three of the component subindicators (i.e., TN, TP, chlorophyll a), and is termed TLI3. For the Upper Waitaki Catchment lakes, several of the lakes are affected by such factors, and therefore TLI3 is used to characterise trophic status (discussed in further in section 2.2).

Table 1-1: Lake types, trophic levels and values of the four key variables that define the different lake types (reproduced from Burns, 2000)

Lake Type Trophic Level Chla Secchi TP TN Depth

(mg m-3) (m) (mg P m-3) (mg N m-3)

Ultra- 0.0 to 1.0 0.13 - 0.33 31 - 24 0.84 - 1.8 16 - 34 microtrophic Microtrophic 1.0 to 2.0 0.33 - 0.82 24 - 15 1.8 - 4.1 34 - 73 Oligotrophic 2.0 to 3.0 0.82 - 2.0 15 - 7.8 4.1 - 9.0 73 -157 Mesotrophic 3.0 to 4.0 2.0 - 5.0 7.8 - 3.6 9.0 - 20 157 - 337 Eutrophic 4.0 to 5.0 5.0 - 12 3.6 - 1.6 20 - 43 337 - 725 Supertrophic 5.0 to 6.0 12 - 31.0 1.6 - 0.7 43 - 96 725 -1558 Hypertrophic 6.0 to 7.0 >31 <0.7 >96 >1558

Environment Canterbury Technical Report 1 The current water quality state of lakes in the Waitaki catchment

Figure 1-1: Visual display of extracted chlorophyll at various concentrations (μg/L) ranging from current baseline average lake-wide for (0.5 μg/L) to the near maximum peak summer chlorophyll value (30 μg/L) predicted in the Ahuriri Arm under various increased nutrient load scenarios (reproduced from Norton et al., 2009)

1.2 Lake SPI Lake SPI (Lake Submerged Plant Index) is a tool for assessing the ecological status of a lake. It makes an assessment of the macrophyte (rooted aquatic plant) community and incorporates two key measures: • Native Condition Index: This assesses the native character of lake vegetation based on the diversity and the extent of indigenous plant communities. Higher scores indicate a better, more diverse, abundant and deeper community. • Invasive Condition Index: This assesses the presence and abundance of exotic invasive plant communities. Higher scores indicate the community is more impacted by exotic species. The Lake SPI index is a combination of the two indicators above, and is generally adjusted to a percentage of a maximum attainable score. This is a form of relativisation, and allows comparisons to be made between lakes. This index has been adopted by the Ministry for the Environment as the key indicator of lake ecological health. Lakes with high loads of glacial flour have naturally low water clarity that limits light penetration and therefore the depth to which macrophytes can grow. While this index may not be particularly relevant in lakes with naturally low water clarity, the relativisation adjustment method outlined above may partially address this issue. Additionally, Clayton et al. (2002) recommend comparing measurements of current lake water clarity with historical lake water clarity to help determine the degree to which anthropogenic effects have driven any changes observed.

1.3 Suitability for Recreation Grade (SFRG) The SFRG gives an indication of the risks associated with faecal contamination to people engaged in contact recreation at a particular swimming site. The poorer the grade, the higher the risk of ingesting pathogenic bacteria or viruses. Environment Canterbury follows guidelines in ‘Microbiological water quality guidelines for marine and freshwater recreational areas’ (MfE & MoH, 2003) for all aspects of the program. Sites graded “Poor” and “Very Poor” are generally considered unsuitable for contact recreation, while sites graded “Good” and ‘Fair’ may be unsuitable following heavy rain. Only lakes specifically monitored for contact recreation have been assessed. The two components to grading an individual site are (see also Table 1-2): 1. The Sanitary Inspection Category (SIC), which generates a qualitative risk assessment of the susceptibility of a water body to faecal contamination based on catchment characteristics; and

2 Environment Canterbury Technical Report The current water quality state of lakes in the Waitaki catchment

2. Historical microbiological results (the 95th percentile of 5 years data). This generates a Microbiological Assessment Category (MAC), which provides a measurement of the actual water quality over time.

Table 1-2: Suitability for recreation grade (SFRG) matrix for freshwater and marine sites (MfE & MoH, 2003)

Microbiological Assessment Category (MAC) Susceptibility to (95th percentile of 5 years data) faecal influence A B C D

Freshwater ≤ 130 131-260 261-550 >550 (E. coli/100ml) E. coli/100 mL E. coli/100 mL E. coli/100 mL E. coli/100 mL

Very low Very good Very good Follow-up* Follow-up*

Sanitary Low Very good Good Fair Follow-up* Inspection Moderate Follow-up* Good Fair Poor Category (SIC) High Follow-up* Follow-up* Poor Very poor Very high Follow-up* Follow-up* Follow-up* Very poor * Indicates unexpected results requiring investigation (reassess SIC and MAC)

2 Method

2.1 Data sources 1. Lake nutrient and chlorophyll A data for calculation of TLI in this report are sourced from Environment Canterbury’s region-wide high country lakes monitoring programme. 2. Lake faecal contamination data has been collected by Environment Canterbury for the Contact Recreation water quality program which runs between November and March every year. 3. NIWA has produced a series of reports under contract to Environment Canterbury on the ecological health of a number of the Waitaki lakes using the LakeSPI methodology. Outputs from consultancy LakeSPI reports including the LakeSPI index and its component index’s as key outputs have been collated for this report. This information is accessible on the NIWA LakeSPI website (http://lakespi.niwa.co.nz/). Faecal contamination and suitability for contact recreation information is collected annually at graded swimming beaches by Environment Canterbury during the summer months (November-March). These data have previously been analysed and reported by Robinson and Bolton-Ritchie (2013). The information reported here has been collated from that report. NIWA has also collected water quality data from Lakes Benmore and Aviemore. It is acknowledged that there may be differences in the reported estimates of lake trophic state between NIWA and Environment Canterbury as a result of differences in sampling methodology, sampling location and sampling date. Environment Canterbury and NIWA also submit water samples to different testing laboratories that differ in their analytical protocols and therefore results may differ as a consequence. It is important that the methodology used by Environment Canterbury in assessing lake trophic state is consistent, and long term trends can be confidently assessed from a single data set.

Environment Canterbury Technical Report 3 The current water quality state of lakes in the Waitaki catchment

2.2 Lake sampling method In the Environment Canterbury high country lakes monitoring program we use a helicopter to visit approximately 30 lakes across the Canterbury region in a day. This imposes a number of limitations on the type of sampling that can be carried out, but also allows a greater number of sites to be monitored than would be possible under the same monitoring resources using a boat. The NZ lake monitoring protocols (Burns et al., 2000) stipulates Secchi disc clarity measurements should be made at each site on each occasion. The Burns et al. (2000) protocols also specify requirements for temperature profiling to be conducted, and at each site any depth discontinuity (the metalimnion) be identified with four samples taken at equally spaced distances over the depth of the epilimnion (from the surface to the metalimnion), as well as a sample of the hypolimnion. If the lake is not thermally stratified then samples should be taken over the full depth of the lake. Neither of these sampling methods are possible during helicopter sampling. In the Environment Canterbury monitoring programme we take a depth integrated water sample of the top 10 metres of each lake sampled by dropping an empty weighted bottle to a depth of 10 m, so that it fills over its descent. The upper 10 m depth is the area of the lake visible by most lake users and is likely to be reasonably productive compared to deeper parts of the lake due to light attenuation in deeper parts of the lake. Lakes under 10 m deep are sampled just below the surface to avoid entrainment of lake bed sediment during sampling. Measurements taken from this part of the lake and associated management strategies are therefore likely to protect most of the values associated with these systems. Further, the limited photic depth of the glacially influenced Waitaki lakes indicates the greatest chlorophyll concentrations are likely to be found in the upper part of the water column. This is also consistent with the method employed by NIWA for lake TLI sampling. Additionally, instead of the ideal twelve month sampling program as stipulated by Burns et al. (2000), we sample between December and April. This is the period when the lakes are used most frequently, and is also the period when the lakes are most likely to be developing effects related to eutrophication and stratification. Sampling four or five times over the full calendar year may give a better indication of average lake state, but is unlikely to be frequent enough to accurately determine summer trophic status or detect trends over the productive summer months. Additionally, helicopter sampling Canterbury high country lakes during the winter months poses a number of logistical and health and safety issues. We consider that this sampling program is a pragmatic approach to lake monitoring in Canterbury, while meeting current budget and safety constraints (Meredith, 2004) and providing this protocol is adhered to, data will illustrate consistent trend information. Samples for the contact recreation program are taken weekly from the lake shore following procedures as stipulated in the Microbiological water quality guidelines for marine and freshwater recreational areas (MfE & MoH, 2003).

2.3 Trophic Level Index calculations We follow protocols set out in the Protocol for Monitoring Trophic Levels of New Zealand Lakes and Reservoirs (Burns et al., 2000) for calculation of the Trophic Level Index. An annual TLI3 score is calculated from the annual average of the three measured parameters (total nitrogen, total phosphorus, chlorophyll A), and averaged into an annual lake TLI3 score. Secchi disc measurements are not carried out by Environment Canterbury because the glacial flour found in many of the lakes in the region reduces water clarity naturally, and means water clarity is not always related to phytoplankton production or lake nutrient enrichment.

2.3.1 Variation in TLI estimates between NIWA and Environment Canterbury An analysis of historical water quality data for Lake Benmore collected by NIWA and Environment Canterbury yielded statistically significant differences between the two datasets. When used to calculate TLI estimates for Lake Benmore, the two datasets resulted in a significant difference in estimated trophic state. Differences between TLI estimates was expected due to differences in sampling location, sampling methods, sample treatment, laboratory analytical methods and sampling dates. However, the TLI discrepancies between the datasets were large and consistent enough to warrant more detailed investigation into the possible causes.

4 Environment Canterbury Technical Report The current water quality state of lakes in the Waitaki catchment

We carried out an investigation on a single sampling occasion in mid-November (17/11/14) on Lake Benmore to evaluate sampling and laboratory protocol differences and their possible effects on TLI estimates. This involved simultaneous water quality sampling by both Environment Canterbury and NIWA using their respective sampling methods at seven sites on the lake. NIWA samples were sent to three different laboratories (Waikato University, Hill laboratories (which is used by ECan), NIWA lab) for analysis of Total nitrogen, Total phosphorus, and Chlorophyll A concentrations. Environment Canterbury samples were sent only to Hill laboratories.

NIWA and Environment Canterbury scientists have discussed these recent results and believe that it is likely the larger observed differences in historical TLI measurements are a result of different sampling locations. As glacial flour settles along the length of the lake, increased light penetration is likely to allow greater growth of phytoplankton. Critically, Environment Canterbury has historically measured water quality at sites further up Lake Benmore. To address this issue, Environment Canterbury has recently aligned their water quality monitoring sites with the NIWA site (which are also the consent monitoring sites). It is hoped that this will help rectify the issue. In light of these findings, it is considered appropriate to use the NIWA dataset to estimate TLI in Lake Benmore. In light of these findings, the NIWA Lake Benmore model was used to predict TLI at these specific points rather than producing an average TLI score from a number of points from each arm.

It is clear that any lake monitoring program needs to have internally consistent sampling methods, sampling locations and lab analysis methods to be able to detect changes in lake state over time, and we have put processes in place to ensure that this occurs. If there are multiple sampling programs occurring they should, as much as possible, have the same sampling methods, sampling locations and lab analysis methods to remain comparable. Furthermore, lab comparisons may be considered in the future to ensure confidence in the data collected.

Environment Canterbury Technical Report 5

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2.4 Monitoring sites

Table 2-1: Sites included in Environment Canterbury’s monitoring programs (sites in Black are monitored for the regional high country lakes

monitoring program. Sites in Red are monitored for regional contact recreation program) catchment Waitaki the in lakes of state quality water current The

Site ID Source Site Name NZMG X NZMG Y NZTMX NZTMY Lake classification SQ31096 Lake Alexandrina Mid lake, surface 2305600 5694000 1395632 5132370 Small to Medium High Country Lake

SQ32908 Lake Tekapo/Takapō Centre, surface 2311557 5694042 1401590 5132414 Large High Country Lake SQ34908 Lake Pūkaki Mid lake at southern end 2285797 5675254 1375829 5113615 Large High Country Lake SQ32909 Centre, surface 2292672 5653482 1382715 5091839 Large High Country Lake SQ34907 Lake Benmore Centre- northern arm 2288092 5636130 1378141 5074481 Artificial on -river Lake SQ35639 Lake Benmore Ahuriri Arm 2280270 5626670 1370321 5065013 Artificial on -river Lake SQ35640 Lake Benmore Above Dam 2287977 5623572 1378032 5061918 Artificial on -river Lake

SQ35641 Lake Aviemore 2295464 5615968 1385526 5054316 Artificial on -river Lake

Environment CanterburyTechnical Report SQ35823 Lake McGregor Centre of Lake 2306958 5693747 1396990 5132117 Small to Medium High Country Lake SQ20927 Lake Middleton Mid lake 2258500 5654000 1348530 5092343 Small to Medium High Country Lake SQ10805 Kellands Pond Second Point-Edge 2275974 5652188 1366011 5090539 Artificial, other, Lake SQ35833 Kellands Pond Centre Of Lake 2275950 5652303 1365987 5090653 Artificial, other, Lake SQ20928 Lake Middleton Main swimming area (E side of Nth end) 2258544 5654633 1348573 5092976 Small to Medium High Country Lake SQ35569 Camping ground 2276156 5655270 1366192 5093621 Artificial on -river Lake SQ20607 Lake Benmore Pumpkin Bay 2277134 5626557 1367184 5064898 Artificial on -river Lake SQ20794 Lake Benmore Sailors Cutting 2278443 5625312 1368494 5063653 Artificial on -river Lake

SQ20801 Lake Aviemore Loch Laird 2286180 5622523 1376236 5060868 Artificial on -river Lake SQ26741 Lake Aviemore Te Akatarawa Camping Ground 2293966 5619380 1384026 5057728 Artificial on -river Lake SQ20805 Lake Aviemore Waitangi 2295868 5619416 1385928 5057766 Artificial on -river Lake

The current water quality state of lakes in the Waitaki catchment

2.5 Assessment method TLI and Lake SPI results since 2009 were used for comparison to objectives in the Land and Water Regional Plan and the Upper Waitaki Zone Implementation Plan (Table 2-2). This allows assessment of average lake status, allowing for episodic events that may drive changes in lake productivity. Contact recreation grades since the summer of 2008/09 have also been compared to pLWRP objectives. Table 2-2: Freshwater lake outcomes for lake management units found in the upper Waitaki catchment

Visual Eutrophication Microbiological Ecological Health indicators quality indicator indicator indicator Management Dissolved Oxygen (min Suitability for unit LakeSPI* Trophic level %) contact Temperature (min Index (TLI*) Colour recreation grade) (max score) Hypolimnion Epilimnion (SFRG)*

Natural state Lakes are maintained in a natural state

Large high Excellent 2 Good country lakes The Small to natural medium colour of High 3 Good sized high 70 90 19 the lake country lakes is not degraded Artificial by more lakes – on High 3 than five Good river Munsell units Suitable for the Artificial 20 Suitable for the purpose of the lake 4 purpose of the lakes - other lake

*Key: Lake SPI = Lake Submerged Plant Indicators from Clayton J, Edwards T, (2002) LakeSPI: a method for monitoring ecological condition in New Zealand lakes (Technical report version 1 Report by NIWA) TLI = Trophic Level Index from: Protocol for Monitoring Trophic Levels of New Zealand Lakes and Reservoirs (Burns 2000) SFRG = Suitability for Recreation Grade from: Microbiological Water Quality Guidelines for Marine and Freshwater Recreational Areas, Ministry for the Environment, June 2003

In addition to the outcomes in Table 2-2 above, strategic policies relating to surface water bodies require them to be managed so that: (a) toxin producing cyanobacteria do not render rivers or lakes unsuitable for recreation or human and animal drinking-water; (b) fish are not rendered unsuitable for human consumption by contaminants; (c) the natural colour of the water in a river is not altered; (d) the natural frequency of hāpua, coastal lakes, lagoons and river openings is not altered; (e) the passage for migratory fish species is maintained unless restrictions are required to protect populations of native fish; (f) reaches of rivers are not induced to run dry, thereby maintaining the natural continuity of river flow from source to sea, and

Environment Canterbury Technical Report 7 The current water quality state of lakes in the Waitaki catchment

(g) variability of flow, including floods and freshes, is maintained to avoid prolonged “flat-lining” of rivers; to facilitate fish passage; and to mobilise bed material.

3 Results

3.1 Trophic Level Index (TLI3) Over the five years sampled, Lakes McGregor, Tekapo/Takapō and Pūkaki failed to meet their respective pLWRP objectives on one sampling year. The Ahuriri Arm of Lake Benmore, and Lakes Alexandrina, Middleton and Ōhau, all failed to meet pLWRP objectives for more than one year. Table 3-1: TLI results in high country lakes from 2009. Results from Environment Canterbury’s high country lakes monitoring program and NIWA (Highlighted results fail to meet pLWRP objectives) pLWRP Sensitive Trophic Site name Date TLI desired lake status outcome catchment Lake Tekapo/Takapō 2009/10 2.2 OLIGO 2 No 2010/11 2.0 MICRO 2 No 2011/12 1.5 MICRO 2 No 2012/13 1.4 MICRO 2 No 2013/14 1.2 MICRO 2 No Lake Ōhau 2009/10 2.1 OLIGO 2 No 2010/11 2.0 MICRO 2 No 2011/12 1.5 MICRO 2 No 2012/13 2.1 OLIGO 2 No 2013/14 0.9 ULTRA 2 No Lake Pūkaki 2009/10 2.0 MICRO 2 No 2010/11 2.0 OLIGO 2 No 2011/12 1.6 MICRO 2 No 2012/13 1.3 MICRO 2 No 2013/14 1.0 ULTRA 2 No Lake Benmore - Haldon Arm (NIWA) 2008/09 2.7 MESO 3 No 2011/12 2.4 MESO 3 No 2012/13 2.5 MESO 3 No Lake Benmore - Ahuriri Arm (NIWA) 2008/09 2.8 MESO 3 No 2011/12 2.9 MESO 3 No 2012/13 3.3 MESO 3 No Lake Benmore - above dam (NIWA) 2008/09 2.2 MESO 3 No 2011/12 2.5 MESO 3 No 2012/13 2.6 OLIGO 3 No Lake Aviemore 2009/10 2.2 OLIGO 3 No 2010/11 2.0 OLIGO 3 No 2011/12 1.8 MICRO 3 No 2012/13 2.3 OLIGO 3 No 2013/14 1.4 MICRO 3 No Lake Alexandrina 2009/10 3.1 MESO 3 Yes 2010/11 2.9 OLIGO 3 Yes 2011/12 3.0 MESO 3 Yes 2012/13 3.0 OLIGO 3 Yes 2013/14 3.2 MESO 3 Yes Lake McGregor 2011/12 3.3 MESO 3 Yes

8 Environment Canterbury Technical Report The current water quality state of lakes in the Waitaki catchment

pLWRP Sensitive Trophic Site name Date TLI desired lake status outcome catchment 2012/13 3.0 OLIGO 3 Yes

Lake Middleton 2011/12 3.5 MESO 3 Yes 2012/13 3.6 MESO 3 Yes

Kellands Pond - centre–TLI3 2011/12 3.0 MESO 4 Yes 2012/13 3.2 MESO 4 Yes

Kellands Pond - edge - TLI2 2009/10 3.2 MESO 4 Yes 2010/11 2.8 OLIGO 4 Yes 2011/12 2.6 OLIGO 4 Yes 2012/13 3.8 MESO 4 Yes

Kellands Pond - edge – TLI3 2013/14 3.7 MESO 4 Yes Sept 2012/Dec Wairepo Arm of Lake Ruataniwha1 3.2 MESO 4 Yes 2012 Wairepo Arm of Lake Ruataniwha2 2011/12 3.0 OLIGO 4 Yes 2012/13 2.9 OLIGO 4 Yes 1. Kelly, D. 2013 2. Sutherland et al. 2013

Table 3-2: Average TLI result (incorporating NIWA data) between 2009/10 and 2013/14 (five years). Highlighted cells breach pLWRP or ZIP limits

Upper Waitaki CWMS ZIP TLI Site name Average TLI pLWRP TLI objective limit Lake Tekapo/Takapō 1.7 2 Lake Ōhau 1.7 2 Lake Pūkaki 1.6 2 Lake Benmore - Haldon Arm (NIWA) 2.5 3 2.6 Lake Benmore - Ahuriri Arm (NIWA) 3.1 3 2.6 Lake Benmore - above dam (NIWA) 2.6 3 2.6 Lake Aviemore1 1.9 3 Lake Alexandrina 3.0 3 Lake McGregor 3.2 3 Lake Middleton 3.6 3 Kellands Pond 3.2 3 1. Additional NIWA data for Lake Aviemore exists from the summer of 2012/13, with a TLI of 3.0. It is likely the driver for the different TLI estimates between NIWA and ECan is similar to that discussed for Lake Benmore in section 2.3.1. While it has not been incorporated to derive a five year average due to the short data record, it should be considered useful additional information.

Environment Canterbury Technical Report 9 The current water quality state of lakes in the Waitaki catchment

3.2 Lake SPI Lakes Benmore, Tekapo/Takapō and McGregor failed to meet pLWRP LakeSPI objectives. All other lakes surveyed met objectives (Table 3-3).

Table 3-3: Waitaki catchment LakeSPI results (highlighted results fail to meet pLWRP objectives) Overall Date Native Invasive LakeSPI pLWRP Source condition carried Index Index Index objective score out Lake Alexandrina 57 39 57 High High May-09 Lake Tekapo/Takapō 34 4 50 Moderate Excellent Mar-12 Lake Ōhau 63 0 78 Excellent Excellent May-09 Lake Benmore - Haldon Arm 37 60 37 Moderate High 2012 Lake Benmore - Ahuriri Arm 43 61 40 Moderate High Jan-13 58 49 53 High High Dec-12 Lake Aviemore 59 51 54 High High Dec-12 Lake McGregor 63 64 48 Moderate High Mar-12 Lake Middleton 84 56 57 High High Mar-12

Suitable for Kellands Pond 40 69 38 Moderate purpose of Feb-12 lake

Suitable for Wairepo Arm of lake 40 72 37 Moderate purpose of Mar-14 Ruataniwha lake

3.3 Contact recreation grade (Suitability for Recreation Grade - SFRG)

Table 3-4 contains results from the contact recreation water quality monitoring sites in a number of the Waitaki lakes area since the summer of 2008/09. While most sites meet objectives, several do not. Sites at Waitangi and Loch Laird on Lake Aviemore regularly have high E .coli results that result in a fair and poor grading respectively. Additionally, sampling at Lake Middleton indicates an increase in faecal contamination in recent years, with a resultant shift in the SFRG from “Good” to “Fair”.

10 Environment Canterbury Technical Report The current water quality state of lakes in the Waitaki catchment

Table 3-4: Lake contact recreation site results and since November 2008 SFRG 95%ile Micro Site Suitability for LWRP Site Year E. coli Assessment inspection Recreation desired result Category category Grade (SFRG) outcome Lake Tekapo/Takapō beach 2008/09 175 B Moderate Good Good 2009/10 198 B Moderate Good Good 2010/11 148 B Moderate Good Good 2011/12 195 B Low Good Good 2012/13 140 B Low Good Good Lake Ruataniwha - camp ground 2008/09 Insufficient data Good 2009/10 Insufficient data Good 2010/11 198 B Moderate Good Good 2011/12 150 B Moderate Good Good 2012/13 129.8 B Moderate Good Good Lake Aviemore - Waitangi 2008/09 455 C Moderate Fair Good 2009/10 383 C Moderate Fair Good 2010/11 428 C Moderate Fair Good 2011/12 427.5 C Moderate Fair Good 2012/13 405 C Moderate Fair Good Lake Aviemore - Te Akatarawa 2008/09 77 A Moderate Good Good camp 2009/10 128 A Moderate Good Good 2010/11 168 B Moderate Good Good 2011/12 165 B Moderate Good Good 2012/13 165 B Moderate Good Good Lake Aviemore - Loch Laird 2008/09 682 D Moderate Poor Good 2009/10 694 D Moderate Poor Good 2010/11 798 D Moderate Poor Good 2011/12 820 D Moderate Poor Good 2012/13 820 D Moderate Poor Good Lake Benmore - Sailors Cutting 2008/09 290 C Moderate Fair Good 2009/10 195 B Moderate Good Good 2010/11 195 B Moderate Good Good 2011/12 106.3 A Moderate Good Good 2012/13 61 A Moderate Good Good Lake Benmore - Pumpkin Bay 2008/09 115 A Moderate Good Good 2009/10 138 B Moderate Good Good 2010/11 223 B Moderate Good Good 2011/12 222.5 B Moderate Good Good 2012/13 231.3 B Moderate Good Good Lake Middleton 2008/09 126 A Moderate Good Good 2009/10 210 B Moderate Good Good 2010/11 400 C Moderate Fair Good 2011/12 455 C Moderate Fair Good 2012/13 385 C Moderate Fair Good

Environment Canterbury Technical Report 11 The current water quality state of lakes in the Waitaki catchment

4 Case studies These two case studies have been presented to illustrate the effect of land use pressures on lakes in the upper Waitaki catchment.

4.1 Lake Alexandrina Lake Alexandrina is a medium sized high country lake immediately west of Lake Tekapo/Takapō. It covers 658 hectares at approximately 732 metres above sea level. The lake has three main basins (Cass, Glenmore and Godley) with a maximum depth of 27 m and an average depth of 13.6 m (Hayes 1980). Main inflows to the lake are Scotts Creek (115 l/sec), Muddy Creek (50 l/sec), Knowles Knob Stream (33 l/sec) and direct groundwater inputs (350 l/sec) (Taranaki Catchment Commission (T.C.C.) 1987). The average water residence time is 4.15 years (Waitaki Catchment Commission and Regional Water Board 1984). The lake is highly regarded as a trout and salmon fishing destination, and the three hut communities that are established around the lake are partly a testament to this. The lizard and bird populations around the lake are considered to be worthy of protection, with southern crested grebes and regularly found on and near the lake. Native fish species in the lake include long finned eels, kōaro, and common and upland bullies. Lake Alexandrina is also highly valued for its aesthetic values (see Figure 4-1).

Figure 4-1: Lake Alexandrina Concerns regarding degrading water quality in Lake Alexandrina were raised as early as the 1970s. Catchment land use development of inflow tributaries and the development of the huts communities were widely considered to be driving the changes observed in water quality. Regular algal blooms (including the potentially toxic Ananbaena sp.) were noted between 1980 and 1985 (T.C.C., 1987) and large macrophyte beds dominated by the charophyte Chara globularis were also noted around the huts communities (Hayes, 1980). Chlorophyll A concentrations in the lake ranged between 400-3800 µg/L between November 1978 and March 1979 (Hayes, 1980). These results are high, indicating the lake could have been classified as hypertrophic using the Trophic Level Index. As a result of these studies, a number of investigations were carried out on the water quality and ecology of the lake. These studies indicated nutrient concentrations in the lake were greater near the huts and in inflowing tributaries compared to other areas in the lake (Hayes, 1980; T.C.C., 1987). Two investigations focussed on phosphorus loading to the lake (Hoare, 1982; Lovegrove, 1985) and concluded the huts communities were unlikely to be contributing large volumes of phosphorus to the

12 Environment Canterbury Technical Report The current water quality state of lakes in the Waitaki catchment

lake. The bulk of the load was predicted to be entering the lake within surface and groundwater inflows elsewhere. Management of phosphorus loads became the priority for lake management (Elliott and Sorrell, 2002; Ward Smith et al., 1985), and interim guidelines were developed that included a suite of rules that attempted to address inputs from both agricultural areas and the huts communities. Recent TLI monitoring results from Lake Alexandrina indicate nutrients are still elevated relative to other lakes in the area. However, comparisons of recent chlorophyll A concentrations with those recorded during the 1980s suggest the lake is significantly less productive now. Annual average chlorophyll A concentrations over the last five years ranged between 0.2-5.3 µg/L. There have been no algal scums (likely to be cyanobacteria) reported to Environment Canterbury over recent years. Analysis of recent results using relationships between nitrogen and phosphorus and chlorophyll A developed by Burns (2000) indicates phosphorus may currently be more frequently limiting to phytoplankton growth. Continued phosphorus management is therefore an ongoing priority. LakeSPI results from Lake Alexandrina indicate the lake is becoming increasingly impacted by invasive macrophytes. The invasive index has risen from 19 in 1982 to 39 in 2009. It is possible that nutrients that were previously assimilated by phytoplankton are now being increasingly utilised by a larger biomass of exotic macrophytes, contributing to their increased abundance.

4.2 Kellands Pond Kellands Pond is a small man made pond south of that covers approximately 22 hectares. Flow into the pond is predominantly groundwater dominated. As a result, the colour of the water contrasts with the turbid glacially influenced water of Lake Ruataniwha (and to a lesser extent, the Wairepo Arm of Lake Ruataniwha). A culvert linking Kellands Pond to nearby Wairepo Arm predominantly carries surplus water from the pond to Wairepo Arm, but can also carry water back into the pond. It is likely this variation in flow direction is caused by regular fluctuations in the water level in the Ohau Canal and Lake Ruataniwha caused by power generation patterns of power station (see Figure 4-2). The pond margins have been developed for recreational access, and are used recreationally by swimmers, picnickers and anglers. Central Fish and Game Council hold a “Take a kid fishing” day at the pond each year.

Figure 4-2: Kellands Pond and surrounding water bodies

In 2003 the land on the western side of SH8 around Kellands Pond was developed as an intensive irrigated dairy operation. The property owner currently grazes approximately 3850 cows in the Kellands Pond catchment. Prior to mid-2009, nitrate and nitrite nitrogen (NNN) concentration had been consistently low, but from this point concentrations began to increase. Analysis of water quality results shows a statistically significant trend indicating NNN concentrations have been increasing on average 45% per year between 2003 and October 2013 (Table 4-1 and Figure 4-3). Current nitrogen concentrations are significantly elevated compared to other lakes in the Upper Waitaki zone, and place Kellands Pond in the upper eutrophic range. Additionally, water clarity has decreased (as turbidity has increased significantly over the same period) (Table 4-1). This decrease in clarity is likely to be related to an increase in phytoplankton production. It is also possible that it could be influenced

Environment Canterbury Technical Report 13 The current water quality state of lakes in the Waitaki catchment

by an increase in the frequency or duration of periods where turbid Lake Ruataniwha water enters Kellands Pond through the culvert, but there is no explanation of why this should have occurred over this period. While there are indications phytoplankton concentrations may have increased, TP and Chlorophyll A are still relatively low and in the lower mesotrophic range (Kelly, 2013). Any increase in phosphorus load to Kellands Pond is likely to result in a reduction in clarity and possible loss of lake values. E. coli concentrations have not significantly increased over the same period. Rafts of algal material, and unidentified black benthic mats were noted, and persisted on the bed of the pond during the summer of 2009/10. They have not been noted since.

0.7

0.6

0.5

0.4

0.3

0.2

0.1 Nitrate and Nitrite Nitrogen (mg/L) Nitrogen Nitrite and Nitrate

0 1/09/2002 6/07/2009 1/04/2012 14/01/2004 28/05/2005 10/10/2006 22/02/2008 18/11/2010 14/08/2013 27/12/2014

Figure 4-3: Nitrate and nitrite nitrogen concentrations in Kellands Pond 2004-2013

Table 4-1: Trends in nitrate and nitrite nitrogen and turbidity in Kellands Pond from 2004- 2013

Relativised Seasonal Kendall Slope Estimator (% change/year)

Nitrate + Nitrite Nitrogen +44.8

Turbidity +7.9

5 Discussion and conclusions Lakes Tekapo/Takapō and Pūkaki have failed to meet the current plan TLI objectives on just one occasion. Each time, this was a result of higher than normal total phosphorus concentrations. The two occasions TLI exceeded plan objectives at Lake Ōhau were similarly driven by high phosphorus concentrations. It is likely a flood event in the catchment of these lakes has increased the sediment load and associated total phosphorus loads. Generally, there has not been an associated phytoplankton response, as evidenced by the comparatively low chlorophyll A results taken on the same sampling occasions (Appendix 2). Filippelli and Souch (1999) note that glacial flour tends to

14 Environment Canterbury Technical Report The current water quality state of lakes in the Waitaki catchment

enriched in mineralised phosphorus, which is not readily bioavailable to aquatic plants and phytoplankton. Lake Middleton regularly fails to meet current plan objectives. Because of the limited sampling history in this lake it is not certain if these TLI results are a deviation from a historic state driven by changes in land management practises. However, compared to results dating back to 1996/97 (ECan unpublished data) it is likely the lake has produced more algal biomass in recent times. A recent increase in the amount of faecal contamination in the lake also suggests a change in land use practices in the area. The small catchment and inferred longer water residence time also makes the lake particularly susceptible to effects of eutrophication. Not surprisingly, the limited sampling at Lake McGregor (which Lake Alexandrina flows into) indicates a similarly high level of algal productivity and failure to meet TLI objectives. Lake Alexandrina regularly exceeds TLI objectives (discussed in greater detail in section 4.1). Past and present land uses continue to affect lake water quality, although trends suggest improvement in water quality over the long-term. The Ahuriri Arm of Lake Benmore has also exceeded TLI objectives in recent years, and has a much higher level of productivity than the other large glacial lakes in the Waitaki Catchment. This is thought to result from its relatively small inflows, longer residence time, and higher concentrations of nutrients in inflowing tributaries than other large lakes in the area (Norton et al., 2009, Sutherland et al., 2013). Atypically low TLI scores for a number of lakes (especially those with shorter residence times) were observed in for the 2013/14 are likely to be related to the very low rainfall and river flows over this summer monitoring period (Figure 5-1). The lack of large flood events was especially evident. It is likely that both nitrogen and phosphorus loads to lakes over this period were low, with little overland flow or land-surface recharge of groundwater systems. Mixing of the water column would have been limited as a result of low inflows, with an associated increase in water residence times. The combination of these three effects has resulted in a number of lakes having reduced TLI ranges over the 2013/14 summer. While Kellands Pond currently meets plan objectives, a significant increase in nitrogen concentration over time increases the risk of this water body becoming increasingly productive (discussed in more detail in section 4.2). This is a case study of a lake with a catchment dominated by intensive irrigated agriculture.

Figure 5-1: Recorded flow volume in the Ahuriri River at SH8 July. 2013 – June 2014

Summer sampling period

Environment Canterbury Technical Report 15 The current water quality state of lakes in the Waitaki catchment

LakeSPI results indicate several lakes in the area have undergone invasion by tall invasive macrophytes species (principally Elodea canadensis and Lagarosiphon major) resulting in compromised native macrophyte communities. Lake McGregor, Kellands Pond and the Wairepo Arm of Lake Ruataniwha have especially high coverage by invasive macrophytes. Researchers commented that approximately 51-75% of the bed of Wairepo Arm across the entire depth range was covered in Elodea. Both arms of Lake Benmore fail to meet pLWRP LakeSPI objectives, largely as a result of the invasive oxygen weeds Lagarosiphon major and Elodea canadensis. While these plants grow in sediment and source some nutrients from their roots, the addition of nutrients to the water column increases growth rates in these oxygen weed species (Rattray et al., 1991, Madsen and Baatrup-Pederson 1995). Low LakeSPI results in Lake Tekapo/Takapō are likely a result of the extreme glacial nature of these lakes, where naturally reduced clarity and settlement of glacial flour limits the depth to which plants can grow. Artificial water level fluctuations are also likely to limit the ability of macrophyte to become established. The current state of the macrophyte community in Lake Tekapo/Takapō is likely to be close to reference condition, despite not meeting LWRP targets. LakeSPI was not developed to be particularly effective or responsive for assessing the state of these glacially fed lakes, and scores could also be affected by water level fluctuations for a number of lakes affected by hydro-development (James 2002; Sutherland et al., 2012). Several sites monitored to assess their suitability for contact recreation did not meet pLWRP targets. High results at Loch Laird often coincide with spills from the directly upstream. This site is inundated when the Benmore Dam spills, and the high concentrations periodically recorded at this site are likely to be a result of inundation of grazed land and re-suspension of bed sediments containing faecal matter. The drivers for the high results at the Waitangi campground are less clear. A site at the Aviemore campground a short distance away has much better results, so the cause of the poorer results is likely to be localised. Faecal contamination at Lake Middleton appears to have increased in recent years. Possible contamination sources include the campground on the shores of the lake, increased construction of dwellings, or pastoral grazing near the western shore. In summary, while most lakes in the Upper Waitaki catchment are in good ecological health with reasonably low trophic, it is clear that land use in the immediate and wider catchments of some of these lakes is having a negative effect on the and plant communities, as well as their suitability for recreational uses including safe contact recreation.

6 Acknowledgements Thanks to Dr David Kelly (Cawthron) and Dr Tim Davie for providing peer review and useful comments which improved this report.

7 References Burns, N.M.; Rutherford, J.C.; Clayton, J. 1999. A monitoring and classification system for New Zealand lakes and reservoirs. Journal of Lakes Research & Management 15(4): 255-271. Burns N, Bryers G, Bowman E. 2000. Protocol for Monitoring Trophic Levels of New Zealand Lakes and Reservoirs. Prepared for Ministry of the Environment by Lakes Consulting, March. Carlson, R.R. 1977. A trophic state index for lakes. Limnology and Oceanography. 22:361-369. Chapra, S.C. and Dobson, H.F.H. 1981. Quantification of the lake typologies of Naumann (surface quality) and Thienemann (oxygen) with special reference to the Great lakes. J. Great lakes Res. 7: 182-193. Clayton J, Edwards T, Froude V. 2002. LakeSPI: A method for monitoring ecological condition in New Zealand lakes. Technical Report Version 1. NIWA Client Report HAM2002-011. Edmonds, J., Dwyer, B., Edwards, M. & Bull, J. 1980. Lake Alexandrina Study, 1980. A public discussion document. Jointly prepared and published by the Department of Lands and Survey, Town and Country Planning Division, Ministry of Works and Development, Mackenzie County Council and South Canterbury Acclimatisation Society.

16 Environment Canterbury Technical Report The current water quality state of lakes in the Waitaki catchment

Elliott. S, Sorrell. B. 2002. Lake Managers' Handbook: Land-Water Interactions. Prepared for the Ministry for the Environment. Filippelli GM, Souch, C 1999. Effects of climate and landscape development on the terrestrial phosphorus cycle. Geology 27: 171-174. Hayes, J., W. 1980. An ecological survey of Lake Alexandrina. Unpublished report, Department of Zoology, , Christchurch. Hayes, J., W. 1986. Fish and fisheries values of Lake Alexandrina and their sensitivity to eutrophication. N.Z Ministry of Agriculture and Fisheries, Fisheries Environmental Report No. 63. 45p. Hoare, R.,A. 1982. Lake nutrient load calculations: a management tool. Soil and Water 18(3): 14-17. James, M.R. 2002. Lake Managers Handbook: Lake Level Management. Ministry for the Environment, Wellington, 87p. Kelly, D. 2013. Wairepo Arm and Kellands pond water quality update 2012. Cawthron Report 2284. Prepared for Holland Beckett on behalf of Five Rivers Limited. 20 pages. Lovegrove, DJ. 1985. Lake Alexandrina: a case for non-point source pollution management? Master of Science dissertation, Centre for Resource Management, University of Canterbury and Lincoln College. Madsen, T., Baattrup-Pedersen, A. 1995. Regulation of growth and photosynthesis performance in Elodea canadensis in response to inorganic nitrogen. Functional Ecology 9: 239–247. Meredith, A.S., 2004: Monitoring of the Water Quality of Canterbury High Country Lakes. Environment Canterbury Technical Report: U04/34. Christchurch. 32pp. Ministry for the Environment and Ministry for Health. 2003. Microbiological Water Quality Guidelines for Marine and Freshwater Recreational Areas. Ministry for the Environment and Ministry of Health, Wellington, New Zealand. Norton, N., Spigel, B., Sutherland, D., Trolle, D., Plew, D. 2009. Lake Benmore Water Quality: a modelling method to assist with implementing nutrient water quality objectives. ENC09515; (CHC2009-091). Rattray, M., R., Howard-Williams, C., and Brown, J., M., A. 1991. Sediment and water as sources of nitrogen and phosphorus for submerged rooted aquatic macrophytes. Aquatic Bot. 40:225-237. Robinson, K. and Bolton-Ritchie, L. 2103. Water quality monitoring for contact recreation. Summary of the 2012-2013 season. Unpublished Environment Canterbury Technical report. Snelder, T., Spigel, B, Sutherland, D. and Norton, N. 2005. Assessment of effects of increased nutrient concentrations in streams and lakes of the Upper Waitaki Upper Waitaki Catchment due to catchment land use changes. NIWA Client Report: CHC2005-003. Sutherland, D., Kelly, G. and McDermott, H. 2013. Waitaki Water Quality 2008 – 2013. Prepared for Limited. NIWA client report CHC2013-117. Taranaki Catchment Commission. 1987. Lake Alexandrina water quality study. Prepared for the Waitaki Catchment Commission. 20pp. Waitaki Catchment Commission and Regional Water Board. 1984. Miscellaneous Publication No1. Report on the Hydrology of Lake Alexandrina. Ward-Smith, RA, Stout, VM, Coombridge, WB. 1985. Lake Alexandrina Interim Guidelines for Management of the Catchment. Unpublished report, The Lake Alexandrina Catchment Steering Committee, 67 pp.

Environment Canterbury Technical Report 17 The current water quality state of lakes in the Waitaki catchment

18 Environment Canterbury Technical Report The current water quality state of lakes in the Waitaki catchment

Appendix 1: Physical characteristics of a number of Upper Waitaki lakes (Reproduced from Snelder et al. (2005))

Environment Canterbury Technical Report 19 The current water quality state of lakes in the Waitaki catchment

Appendix 2: All Environment Canterbury TLI results for lakes in the Waitaki catchment

Site name Monitoring period TLc TLn TLp TLI GRADE LWRP desired outcome

Lake Alexandrina Dec 04 - Apr 05 2.5 3.1 2.5 2.7 OLIGO 3 Jan 06 - Apr 06 2.7 3.0 2.3 2.7 OLIGO 3

Jan 07 - Apr 07 3.0 3.6 2.8 3.1 MESO 3

Jan 08 - Apr 08 3.2 3.6 2.6 3.1 MESO 3

Jan 09 - Apr 09 3.3 3.5 3.2 3.3 MESO 3

Dec 09 - May 10 2.9 3.5 2.9 3.1 MESO 3

Dec 10 - Apr 11 2.4 3.4 3.0 2.9 OLIGO 3

Dec 11 - May 12 2.4 3.5 3.1 3.0 MESO 3

Jan 13 - Apr 13 2.2 3.6 3.2 3.0 OLIGO 3

Dec 13- Apr 14 3.2 3.4 2.9 3.2 MESO 3

Lake Tekapo/Takapō Dec 04 - Apr 05 0.5 1.5 1.9 1.3 MICRO 2 Jan 06 - Apr 06 1.5 1.7 1.2 1.5 MICRO 2

Jan 07 - Apr 07 1.0 1.9 1.3 1.4 MICRO 2

Jan 08 - Apr 08 1.9 1.0 0.6 1.2 MICRO 2

Jan 09 - Apr 09 1.9 1.1 2.4 1.8 MICRO 2

Dec 09 - May 10 1.9 1.6 3.0 2.2 OLIGO 2

Dec 10 - Apr 11 1.4 1.4 3.1 2.0 MICRO 2

Dec 11 - May 12 1.9 1.2 1.6 1.5 MICRO 2

Jan 13 - Apr 13 0.9 0.8 2.6 1.4 MICRO 2

Dec 13- Apr 14 1.3 1.0 1.4 1.2 MICRO 2

Lake Ōhau Jan 06 - Apr 06 1.9 1.5 0.9 1.4 MICRO 2 Jan 07 - Apr 07 1.7 2.2 1.2 1.7 MICRO 2

Jan 08 - Apr 08 1.3 1.0 0.9 1.1 MICRO 2

Jan 09 - Apr 09 2.3 1.1 2.3 1.9 MICRO 2

Dec 09 - May 10 1.5 1.9 2.8 2.1 OLIGO 2

Dec 10 - Apr 11 1.6 1.0 3.3 2.0 MICRO 2

Dec 11 - May 12 1.5 1.0 1.8 1.5 MICRO 2

Jan 13 - Apr 13 2.1 0.9 3.2 2.1 OLIGO 2

Dec 13- Apr 14 0.4 1.1 1.1 0.9 ULTRA 2

L Benmore - Haldon Arm Jan 06 - Apr 06 1.7 1.4 0.7 1.3 MICRO 3 Jan 07 - Apr 07 1.5 1.2 1.6 1.4 MICRO 3

Jan 08 - Apr 08 1.8 1.3 1.5 1.5 MICRO 3

Jan 09 - Apr 09 1.6 1.4 2.0 1.6 MICRO 3

Dec 09 - May 10 1.7 1.9 2.8 2.1 OLIGO 3

Dec 10 - Apr 11 1.6 1.5 3.0 2.0 OLIGO 3

Dec 11 - May 12 1.6 1.0 2.1 1.6 MICRO 3

Jan 13 - Apr 13 1.9 1.2 2.9 2.0 OLIGO 3

Dec 13- Apr 14 1.8 1.2 1.3 1.4 MICRO 3

20 Environment Canterbury Technical Report The current water quality state of lakes in the Waitaki catchment

Site name Monitoring period TLc TLn TLp TLI GRADE LWRP desired outcome

Lake Pūkaki Jan 06 - Apr 06 1.7 1.4 1.1 1.4 MICRO 2 Jan 07 - Apr 07 0.6 1.6 3.0 1.7 MICRO 2

Jan 08 - Apr 08 1.2 1.3 2.6 1.7 MICRO 2

Jan 09 - Apr 09 1.9 1.0 2.9 1.9 MICRO 2

Dec 09 - May 10 1.0 1.5 3.5 2.0 MICRO 2

Dec 10 - Apr 11 0.8 1.3 3.9 2.0 OLIGO 2

Dec 11 - May 12 1.2 1.0 2.6 1.6 MICRO 2

Jan 13 - Apr 13 0.9 0.4 2.6 1.3 MICRO 2

Dec 13- Apr 14 1.1 0.8 1.1 1.0 ULTRA 2

L Benmore - Ahuriri Arm Dec 09 - May 10 2.4 2.3 3.0 2.6 OLIGO 3 Dec 10 - Apr 11 3.1 2.6 3.3 3.0 MESO 3

Dec 11 - May 12 2.4 2.2 2.8 2.5 OLIGO 3

Jan 13 - Apr 13 2.5 2.5 3.4 2.8 OLIGO 3

Dec 13- Apr 14 2.0 2.0 1.8 1.9 MICRO 3

L Benmore -above dam Dec 09 - May 10 2.1 1.8 2.6 2.2 OLIGO 3 Dec 10 - Apr 11 1.5 1.3 3.0 1.9 MICRO 3

Dec 11 - May 12 2.2 1.3 2.0 1.8 MICRO 3

Jan 13 - Apr 13 2.0 1.1 1.5 1.5 MICRO 3

Dec 13- Apr 14 1.5 1.3 1.1 1.3 MICRO 3

Lake Aviemore Dec 09 - May 10 2.6 1.7 2.4 2.2 OLIGO 3 Dec 10 - Apr 11 1.4 1.4 3.2 2.0 OLIGO 3

Dec 11 - May 12 1.8 1.6 2.2 1.8 MICRO 3

Jan 13 - Apr 13 2.4 1.6 3.0 2.3 OLIGO 3

Dec 13- Apr 14 2.0 1.2 1.1 1.4 MICRO 3

Lake McGregor Dec 11 - May 12 2.7 3.7 3.4 3.3 MESO 3 Jan 13 - Apr 13 2.2 3.6 3.2 3.0 OLIGO 3

Kellands Pond - Centre Dec 11 - May 12 2.5 3.7 2.9 3.0 MESO 4 Jan 13 - Apr 13 2.4 4.0 3.1 3.2 MESO 4

Kellands Pond - Edge - TLI2 Jul 03-Jun 04 N/A 1.6 2.8 2.2 OLIGO 4 Jul 05-Jun 06 N/A 2.0 3.0 2.5 OLIGO 4

Jul 06-Jun 07 N/A 2.2 3.4 2.8 OLIGO 4

Jul 07-Jun 08 N/A 2.9 2.0 2.5 OLIGO 4

Jul 08-Jun 09 N/A 2.1 2.3 2.2 OLIGO 4

Jul 09-Jun 10 N/A 3.8 2.6 3.2 MESO 4

Jul 10-Jun 11 N/A 3.6 2.1 2.8 OLIGO 4

Jul 11-Jun 12 N/A 3.3 2.0 2.6 OLIGO 4

Jul 12-Jun 13 N/A 3.9 3.6 3.8 MESO 4

Kellands Pond - Edge - TLI3 Jul 13-Jun 14 3.6 4.8 2.7 3.7 MESO 5 Lake Middleton Apr 96 - Oct 97 2.9 3.7 3.3 3.3 MESO 3 Dec 11 - May 12 3.2 4.0 3.3 3.5 MESO 3

Jan 13 - Apr 13 3.0 4.1 3.7 3.6 MESO 3

Environment Canterbury Technical Report 21 The current water quality state of lakes in the Waitaki catchment

Appendix 3: All NIWA TLI results for lakes in the Waitaki catchment

Monitoring LWRP desired Site name TLI GRADE period outcome L. Benmore Haldon Arm 2008/09 2.7 MESO 3 2011/12 2.4 MESO 3

2012/13 2.5 MESO 3

L. Benmore. Above Dam 2008/09 2.2 MESO 3 2011/12 2.5 MESO 3

2012/13 2.6 MESO 3

L. Benmore. Ahuriri Arm 2008/09 2.8 MESO 3 2011/12 2.9 MESO 3

2012/13 3.3 OLIGO 3

L. Aviemore 2008/09 2.3 MESO 3 2012/13 3.0 OLIGO 3

22 Environment Canterbury Technical Report The current water quality state of lakes in the Waitaki catchment

Appendix 4: All LakeSPI results for lakes in the Waitaki River catchment (Highlighted results fail to meet pLWRP objectives) Overall Date Native Invasive Lake SPI LWRP Source condition carried Index Index result objective score out Lake Alexandrina 57 39 57 High High May-09 67 31 66 High High Mar-01

70 19 74 High High Feb-82

Lake Tekapo/Takapō 34 4 50 Moderate Excellent Mar-12 Lake Ōhau 63 0 78 Excellent Excellent May-09 57 30 60 High Excellent Mar-01

67 25 69 High Excellent Nov-89

56 14 68 High Excellent Feb-82

Lake Benmore - Haldon Arm 37 60 37 Moderate High 2012 Lake Benmore - Ahuriri Arm 43 61 40 Moderate High Jan-13 37 69 34 Moderate High 2012

Lake Aviemore 59 51 54 High High Dec-12 Lake Waitaki 58 49 53 High High Dec-12 Lake McGregor 63 64 48 Moderate High Mar-12 59 62 47 Moderate High Feb-82

Lake Middleton 84 56 57 High High Mar-12

Suitable for Kellands Pond 40 69 38 Moderate purpose of Feb-12 lake

Suitable for Wairepo Arm of Lake Ruataniwha 40 72 37 Moderate purpose of Mar-14 lake

Environment Canterbury Technical Report 23