ISSUE NEWSLETTER OF THE LAKESWATER QUALITY SOCIETY

FOR MORE DETAIL AND OTHER NEWS PLEASE VISIT 01 www.lakeswaterquality.co.nz OCTOBER 2009 LakesNews

this issue Lake Still the Monster P.1 Murky Waters for Trophic Changes in the Lakes P.2 Okere, Kaituna, Perspective from the Chair P.3 and Maketu Gorse is a Water Quality Issue P.4 The diversion wall is doing its Vermicomposting of Lake Weed P.5 job very well for most of Lake Ohau Channel Diversion Wall P.6 Rotoiti. Water quality is the best it has been for many years and Farmer and Science Initiatives P.7 there has been a lot of activity on the lake. However, water Keeping on Track P.8 quality in the Okere Arm, the Kaituna River and the Maketu Acknowledgements : Estuary can only be described Lakes Rotorua & Rotoiti Action Plan as disgusting and severely (EBOP), presenters at the Lakeswater Quality Symposium 2008, and other degraded. Adding insult to referenced authors or sources. injury is the rubbish that now drifts down the arm and collects on the beach by the motor camp and along the edges. The wall Still the Monster has meant that all the water Bill Bayfi eld (CEO, EBOP) highlighted the We must address nutrient discharges from from Lake Rotorua, and what it problem at the 2008 LWQS Symposium. “There land. This huge task can only be achieved contains, is now going directly are four ‘priority lakes’ - Rotorua, Rotoehu, by a combination of best farming practice, down the Okere Arm and into Rotoiti, Okareka - agreed in August 2008 for less intensive farming, more forestry, and the the Kaituna River. shared funding of defi ned restoration costs with retirement of land perhaps via subdivision The wall has been a quick fi x for Central Government …Not all the lakes are incentives. Farmers are implementing, or should Lake Rotoiti but unfortunately equal in terms of water quality, risks, solutions, be, best practice management to minimize the Okere Arm is a reminder or the tools required…For three of the priority nutrient losses. These can substantially reduce that the problem has not gone lakes, the challenges and solutions are very do- the amount of nutrients lost. If properties are away. Until the waters of Lake able. Not so for Lake Rotorua – it is a Monster”. going to be retired from farming or shifted to Rotorua are cleaned up, the Why is Lake Rotorua so different? There is a a less intensive form, compensation will be Okere Arm will continue to large, growing community on the foreshore; needed. suffer. there is intensive land use in the catchment, Lakebed sediments also have a major role including 26 dairy farms; and the large Money is about to be spent on in the trophic state of the lake. The recycling catchment means lengthy lag times between the waterways of the Kaituna of nutrients from sediments is greater when nutrient loss from the land and its arrival in the River and Maketu Estuary bottom waters become deoxygenated, typically lake. The average age of the water entering to improve water quality and from September to May - via temperature the lake is over 60 years - nutrients exported restore healthy eco-systems. stratifi cation, consequent lack of mixing, and by from the back half of the catchment in the However, all the time, money, the decomposition of dead algae which have 1950’s are still yet to reach the lake. and remedial measures about sunk to the bottom. to be put in place will help little Good science tells us that 36% of all If we are to see an early improvement in if water fl owing down from Lake phosphorus coming into Lake Rotorua is natural Lake Rotorua, lake and stream treatments Rotorua remains as dirty as it is. via leaching of rock substrate and geothermal offer our main hope. Much has been done to activity, that farming contributes another 45%, Lake Rotorua will not be fi xed remove phosphorus by fl occulation, and the and urban use, forestry, rain and bush the in our lifetime but we need to Tikitere geothermal removal will be positive. balance of 19%. For nitrogen the story is more ensure that future generations Prof. Hamilton and his team have a huge about intensive land use - 75% of all nitrogen will say that we worked hard to challenge to guide the substantial gains comes from farming, with dairying being the clean it up. (Refer Chairman’s needed. The community have agreed that Lake largest contributor. To restore the lake we have Report, page 3) Rotorua will be restored to a TLI of 4.2 - we all to remove from the catchment 311 tonnes of aim to see this achieved, even though we know nitrogen and 10 tonnes of phosphorus. the challenge is a MONSTER. Trophic Level Indices (TLI) 2003-2008 exceeds Target TLI TLI < 2 Very Poor (Microtrophic) 3 yearly average 3 yearly average 3 yearly average 3 yearly average Water Quality at Target Lake TLI to 2005 TLI to 2006 TLI to 2007 TLI to 2008 Target TLI TLI Okaro 5.6 5.5 5.5 5.0 5.0 Very Poor (Supertrophic) Rotorua 5.0 5.0 4.9 4.2 4.2 Poor (Eutrophic) Rotoehu 4.6 4.5 4.6 3.9 3.9 Average (Mesotrophic) Rotoiti 4.5 4.3 4.1 3.5 3.5 Average (Mesotrophic) Rotomahana 3.8 3.9 3.9 3.9 3.9 Average (Mesotrophic) Rerewhakaaitu 3.4 3.5 3.5 3.6 3.6 Average (Mesotrophic) Okareka 3.2 3.3 3.3 3.0 3.0 Average (Mesotrophic) Tikitapu 3.1 3.1 3.0 3.0 2.7 Average (Mesotrophic) Okataina 2.9 2.9 2.8 2.8 2.6 Good (Oligotrophic) Tarawera 2.8 2.8 2.8 2.9 2.6 Good (Oligotrophic) Rotoma 2.5 2.5 2.5 2.6 2.3 Good (Oligotrophic) Rotokakahi 3.4 3.4 3.5 3.8 3.1 Good (Oligotrophic)

Trophic Level Blue-Green Algae Occur more frequently above a certain TLI level. Blue-green algae blooms can also form in lakes Index (TLI) Poor quality waters can experience blue-green with good water quality, like . The TLI is widely used to algae (cyanobacteria) blooms eg. early Okawa Here a large infl ow of water with a low nitrogen measure changes in the Bay (TLI 5.3), Lake Okaro (TLI 5.7). Lake to phosphorus ratio enters the lake along the nutrient (trophic) status of Rotoehu began to experience algal blooms in shoreline adjacent to Rotomahana. This favours lakes in . This 1994 when the quality of the lake deteriorated blue-green algae and when conditions are calm index considers phosphorus and the TLI increased from 3.7 to 4.8. they can assume bloom proportions and nitrogen levels, as well as visual clarity and algal biomass. Lower is better Changes in the Lakes 2005-2008 – very good quality water Kohji Muraoka, Waikato University student requires a TLI less than 2.0. Nitrogen and Phosphorus Nitrogen and phosphorus are essential plant nutrients. In large quantities they can encourage the growth of algal blooms. High levels of water-bound nitrogen and phosphorous most often come from farm runoff and urban wastewater, but can also come from geothermal sources and deep springs that leach phosphorus from rock substrates. Water Clarity Clarity is measured using a Secchi disc attached to a tape measure. The depth at which the disc disappears from sight is recorded from the tape measure. Chlorophyll a Chlorophyll a is the green pigment in plants used for photosynthesis. The amount in lakes (can also be assessed by remote imaging) is a good indicator of the total quantity of algae in a lake. Rotorua Lakefront Congratulations to the Rotorua District Council for their initiative Over the last three years we have all been Perspective in creating plans to bring together aware of the huge debate over climate the city and the lake front, to take from the Chair change and the need to care for the advantage of one of Rotorua’s environment. We expected EBOP to take best assets, its beautiful lake. John Green a tough stance on Lake Rotorua’s nutrient The full plans are on their website targets and, if anything, increase the www.rdc.govt.nz . LWQS believes Our society has spent a huge amount of tonnages and reduce the time to achieve that these plans must be linked time and effort in addressing the signifi cant them. We were naturally shocked to see with the RDC commitment to defi ciencies in the Lake Rotorua and Rotoiti N targets let out 12 years and 200 years clean up Lake Rotorua, including Action Plan which was released to the respectively, and P targets let out 12 years. the reduction of nutrient fl ows to the lake. If the lake remains public in July 2009. As far as Lake Rotoiti persistently green and murky, as is concerned the planned nutrient targets of Given that the lake plan is a non-statutory document one would have thought that the it has been this year , it will not be 130 t/N/yr and 15 t/P/yr have been achieved an attractive sight at the end of community would prefer to see the actions by the impact of the diversion wall. However the pier. We propose: the water quality in the Okere arm, Kaituna needed to clean up the lake being as detailed - Routine lake water management River and the Maketu estuary has signifi cantly and achievable as possible. Otherwise, measures be included in the deteriorated due to their high concentrations of aren’t we burying our heads in the sand? The design plans to accommodate contaminated water from Lake Rotorua. consequences to the Rotorua district of Lake Rotorua not being cleaned up until 2250, i.e. regular weed harvesting along the frontage, to both reduce nutrients This leads us to focus on Lake Rotorua and 240 year’s time, do not even bear thinking in the lake and generally improve the plans necessary to clean that lake up as about. the amenity soon as practically possible. We are deeply concerned that the draft Lake Rotorua plan, So come on, Rotorua Te Arawa Lakes - That the cleaning of trash from which was agreed by the Action Plan working Strategy Group, EBOP and RDC, let’s see a lake water should be as frequent party after three years of full community and tough but achievable plan of actions to clean as cleaning the pavements and trash from the streets science deliberations, could resurface in July up Lake Rotorua within an acceptable time 2009 (two years later) with such a signifi cant frame. Ultimately you will be judged less on - A management plan for the roll back on nutrient targets. what you say and more on what you do. provision of a separate and detached area for tourists to feed the birds. In New Zealand these water birds, such as the black Original Plan Revised Plan Proposed delay swan, can become a nuisance but From the catchment only June 2007 July 2009 with Revised Plan are of great interest to tourists N target 250 tonnes / year By 2017 By 2029 Delayed 12 yrs - Most importantly, that an 311 tonnes / year By 2050 By 2250 Delayed 200 yrs area be set aside for a large swimming beach to be P target 10 tonnes / year By 2017 By 2029 Delayed 12 yrs developed in the future when the lake water quality improves.

Algae Counts for Ohau Channel and Okere Arm The LWQS has ‘adopted’ the weekly biovolume measurements for the Ohau Channel and Okere Arm as useful indicators of the quality of water fl owing from Lake Rotorua into the Okere Arm and Kaituna River. From March to June 2009 these measurements were consistently above the safe threshold of 4.0 Ref : Michael Quintern (EcoVerm), Roku Mihinui and Hera Smith (Te Arawa Lakes Trust). Vermicomposting Lake Weed There has been signifi cant Lake weed harvesting during 2008/2009 – from alone, 3000 tonnes were harvested (ca. 8 tonne of Nitrogen). A joint project between the Te Arawa Lakes Trust, Fonterra and the Sustainable Farming Fund investigated the composting of lake weeds, pulp mill wastes, and DAF sludge produced during milk processing. A mix of I part lakes weed and 2 parts pulp fi bre was, within 7mths, converted to an excellent compost suitable for application to rural land or other uses. Naturally occurring Arsenic concentration in lake weed was Note : Please avoid the spread of lake weeds. Lake weeds must not be transported to a vermicomposting reduced to acceptable levels at location if other lakes or waterways are enroute. this mix ratio.

Vermicomposting of Lake Weeds, Pulp Wastes, and Milk Processing Wastes Results Key Project Objectives Lake Weeds • Combinations of 1 to 2 parts 1. To fi nd out if various industrial and Compost worms colonised the waste of carbon rich fi bre such environmental organic wastes could be within a few days and started breeding as pulpmill solids and 1 vermicomposted. rapidly. Vermicomposting was fi nished part of lake weeds provide after approximately seven months. All 2. To determine the potential of vermicompost an excellent feedstock for worms had disappeared from the windrows to replace and increase organic carbon compost worms. after nine months. Lake weeds are able to content in soils. accumulate heavy metals from the sediment • Combination of 4 to 8 parts In New Zealand, large quantities of organic and or lake water according to the geological of carbon rich fi bre such wastes are currently being land fi lled, even concentration of the water and sediments. as pulpmill solids to 1 part though the New Zealand government has These may vary from lake to lake or even of DAF sludge from milk encouraged producers to recycle and utilise within the lake. It is recommended that the processing plants provide these wastes. Pulpmill solids and lake weeds heavy metal concentration within samples of an excellent feedstock for are landfi lled in the eastern lake weeds be measured, before considering compost worms. and Dissolved Air Flotation (DAF) sludges vermicomposting and recycling lake weeds • Feedstock mixture with DAF from milk processing plants are land applied on land. The arsenic concentration of the sludge takes approximately with high environmental impact. Soils in the lake weeds used for the trial was 365 mg/ 2 to 3 months before worms eastern Bay of Plenty consist predominately kg. The guidelines for safe application of can colonise windrows. of pumice with very low organic matter biosolids to land in New Zealand allow a content. Recycling organic carbon rich maximum concentration of 20 mg/kg for • Increase of carbon source wastes as fertilisers or soil conditioners has Arsenic as Grade A for land application. All in the feedstock with lake the potential to increase soil organic matter other heavy metals measured for in the lake weeds leads to a wider C/N and as a result increase natural soil fertility. weeds, recorded far below the limits set out ratio of the vermicompost. Successful vermicomposting of these wastes in biosolids guideline. The pulpmill solids • An application of 20 m3 has been reported in scientifi c papers with did not contain high levels of metals and of vermicompost per ha trials mainly conducted at a laboratory scale. therefore could be land applied. By blending (equals 2 mm depth) The aim of this project was to conduct a fi eld lake weeds with pulpmill solids the arsenic approximately 2 tons of trial to determine whether vermicomposting concentration of the fi nished vermicompost carbon is applied to soil. was feasible using local industrial wastes was reduced to a concentration below 1ppm within the local climate. Following analysis of which made the product fi t within the limits of the fi nished product - vermicompost - local Grade A according to the biosolids guidelines. farmers and nurseries were approached to identify potential markets. Weed and Pest Management – Public Consultation Ref. EBOP website www.envbop.govt.nz/ Environment Bay of Plenty (EBOP) is looking at making changes to the way they work with the Gorse Is a Water community to control weeds and pests. These changes may affect you and the weed and pest and work that you carry out on your property. This is the fi rst stage in preparing a regional pest Quality Issue management strategy. Gorse is an invasive and Key facts: Nitrogen-fi xing weed, and has • Council spends $2.1 million on Biosecurity each year infested approx. 900,000ha or • Environment Bay of Plenty requires weed and pest control to be undertaken on approximately 3.3% of New Zealand’s total 4,000 properties every year in the Bay of Plenty land area. Within the Rotorua • Management plans are developed for all new incursions of weeds and pests subject to regulation Lakes catchment many land • Weed and plant pest control is estimated to cost New Zealand over $100 million each year areas have been colonized by • New pest plants become established almost weekly in New Zealand gorse. To fi nd out your views and ideas about the future of pest management EBOP is arranging a series of In a poster presentation at public consultation days (see dates below) across the Bay of Plenty. Everyone is welcome to drop in the LWQS Symposium 2008, at anytime during these sessions to talk to staff, gather information and ask questions. Magesan et al conclude that considerable amounts of the To send your thoughts, register your interest in attending the public meetings, or if you would like Nitrogen continuously fi xed further information email : [email protected] by gorse accumulates in soil and eventually passes into water draining from the site. Groundwater enriched with Consultation days nitrate-N may enter the lake Katikati and Tauranga : Tues 6 October 2009, Katikati Memorial Hall Lounge, 5.30pm - 8.30pm system and contribute to lake water degradation. Nitrate Tauranga and Papamoa : Wed 7 October 2009, Papamoa Recreation Centre, 5.30pm -8.30pm concentrations in soil solution Opotiki : Tues 13 October 2009, Woodlands Hall, 5.30pm - 8.30pm below the gorse rooting zone are sometimes higher than Rotorua : Wed 14 October 2009, Meeting Room, Redwood Forest Visitor Centre, 5.30pm - 8.30pm those acceptable for drinking Whakatane and Awakeri: Thursday 15 October 2009, Awakeri Memorial Hall, 5.30pm - 8.30pm water, but tend to decrease during winter months.

Submissions Current Situation You can also send in a – Why Change? submission (download the form below). EBOP Boundary Control Pest Plants has designed a series of Blackberry, Gorse, Ragwort questions that may help you Current Direction in producing a submission. Land occupiers shall, on Submissions close at 5pm on direction of an Authorised Friday 30 October 2009. Person, destroy blackberry or Submission form gorse within 10 metres of any (217KB, doc) property boundary, or ragwort within 50 metres of any property boundary. To fi nd out more: Current Offences • Current Regional Pest A breach of a statutory Management Strategy obligation creates an offence (2.3MB, pdf) under sections 52 and 53 of the Biosecurity Act 1993. A • Consultation Document breach of any direction is an • Technical Report offence under section 154 of the (1.6MB, doc) Biosecurity Act 1993. Waikato University Ohau Channel Diversion Wall Professor funded David Hamilton by EBOP We set out to examine the effectiveness of A substantial bloom of the blue-green alga the Ohau Channel diversion wall on Lake Microcystis wesenbergii in Lake Rotorua late Professor Rotoiti. Water currents at two sites in Lake in summer 2008-9 did not appear to affect Rotoiti near the diversion wall were somewhat the western end of Lake Rotoiti – except for David Hamilton aligned with the predominant wind directions Okere Arm where the Ohau Channel entered at Rotorua Airport, but currents at the site in – in contrast to blooms of similar magnitude the Ohau Channel outfl ow within the diversion in 2003-5, prior to the wall implementation. A Environment Bay of Plenty wall were relatively consistent and aligned in remote sensing image of the western end of (EBOP) made a major the direction of the diversion wall towards the Lake Rotoiti on 17 November 2008 showed a commitment to the restoration Kaituna outfl ow. Current speeds in the Ohau marked difference in water clarity between the of water quality in the Channel were generally several times larger relatively turbid diversion channel water and Rotorua Lakes through the than at the two Rotoiti stations. Around one the clearer water of Lake Rotoiti. The diversion establishment in 2002 of the year of water quality monitoring data have been wall appears to have greatly reduced inputs Chair in Lakes Management analysed since the completion of the diversion into Lake Rotoiti of nutrient enriched water and Restoration, based in wall. There is an indication of improvement in arising from Lake Rotorua. Correspondingly, Biological Sciences at the water clarity (viz., Secchi depth and turbidity there is preliminary evidence of considerable University of Waikato. A variety measurements) and there have been low improvement in water quality in the eastern of student and collaborative levels of chlorophyll a in Lake Rotoiti following end of Lake Rotoiti, based on increased water projects is funded through the diversion wall completion. clarity, reduced levels of chlorophyll a and lower EBOP initiative. The overall cyanobacterial biomass. aim of projects supported by EBOP is to provide the scientifi c basis to support for informed management decision-making by EBOP, in consultation with Iwi and the community. Professor Hamilton had been with the Department of Environmental Engineering and the Centre for Water Research at the University of Western Australia, and previously gained his PhD at Otago University.

“I hope to develop a predictive Water current speeds and directions 1m above the lake bed at sites within Lake Rotoiti understanding of how lakes but near the Okere Arm, c. 200m apart (left and right) and within the Ohau Channel (middle). function using computer Percentages are based on 15-minute readings from 20 August to 9 September 2008. models, and to link these predictions with focused monitoring, research and management”. Research will focus on the Rotorua group of lakes in the central North Island.

The Chair leads a review Remote sensing image of Ohau Channel, Okawa Bay, of lake research and Kaituna exit and western basin on Lake Rotoiti. Photo monitoring programmes as taken 17 November 2008. Image made available well as undertakes high- through agreement entered into for the licence level investigations into lake from National Space Program Offi ce of the National processes. Staff also participate Applied Research Laboratories for the limited use of ROCST-2 satellite image and data by the University in undergraduate, graduate and of Waikato, and supported through the Global Lake postgraduate teaching, and Ecological Observatory Network (GLEON). The supervise student research on horizontal resolution is 2 m and the image has been lake issues. pan-sharpened from a true colour image through assistance from Mat Allan (University of Waikato). Ref : Dr Stewart Ledgard, Measurement of Nutrient Losses AgResearch, Hamilton Great Work at Animal Inputs

A successful nutrient management project has growth requirements. Farmers therefore made been conducted in the Lake Rerewhakaaitu the following changes – catchment. A rewarding feature has been the • Nil or reduced application of N to effl uent close interaction between farmers and science areas providers through frank discussions, regular farmer meetings and newsletters. • Reduced N fertiliser applications during autumn and winter Lake Rerewhakaaitu is a shallow lake, unique amongst the Rotorua lakes in having catchment • Reduced total N inputs onto the farm mostly comprised of dairy farms. In 2001, EBOP Animal urine patches deposit Phase 2 focused on phosphorus management. reported that lake water quality was satisfactory nitrogen at the equivalent of The measured Olsen P level of soils averaged but noted that nutrient levels were increasing 500-1100kg N/ha. Leaching 65, exceeding the 35-45 optimum. Farmers in streams fl owing into the lake. Farmers within from urine patches is high, recognized the need to reduce average levels the catchment were concerned for the future especially in autumn and so that less P was lost by leaching from these condition of the lake water, and for the possible winter. susceptible Tarawera ash soils. consequence of future constraints on their Sources of leached N farming operations. P losses tend to occur from critical source Effl uent 6% areas, rather than the whole catchment Dung and Soil 9% A two-phase Sustainable Farming Fund (SFF) in general, so research focused on the project was set up to address water quality identifi cation of these areas, and the potential issues by identifying pastoral management for on-farm mitigation. Five mitigation sites were practices in the catchment which could be Urine 85% selected within the catchment, and surface run- changed to minimize the environmental impact off measurements were made to evaluate the on the lake, yet allow sustainable dairy farming effi ciency of P removal. to continue. Mitigation methods 30 Phase 1 focused on Nitrogen management. have included – N loss kg / ha (Rotorua 2007) A farmer survey was conducted and • Filter strips (both OVERSEER® nutrient budgets were calculated 20 grass and artifi cial) for 27 dairy farms. Predicted nitrate leaching was similar to other dairy catchments at 38kg • Sediment traps kg N/ha 10 N/ha/yr. It became clear that accurate area • P-socks fi lled with measurements of effl uent paddocks were critical steel or iron slag to accurate budgeting. 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec • Combinations of the Nutrient loadings for nitrogen and potassium above in the effl uent areas were in excess of pasture Research There is on-going research into the reduction of N losses and leaching. • Altered diet composition by the inclusion of high sugar grasses, or low protein feeds such as maize silage - 20% less N loss • The use of diuretcs such as salt - dilutes urine and increases volume, leading to greater spread and less leaching • For the same level of N intake, N loss from sheep and deer is about half that from beef cattle, due largely to the greater spread of urinary nitrogen • Trials in the use of nitrifi cation inhibitors have shown potential for 20-50% decreased N loss • Wetland development and stream margin plantings – preferably with maintenance and biomass harvesting. Lake Ecosystem Food for Thought Restoration NZ Regional Councils Take Action (LERNZ) The CraFarms Group – which owns 22 farms It is therefore pleasing to see that Regional The LERNZ programme aims to around the central North Island, and is the Councils such as Environment Waikato and identify and remediate threats to biggest private dairy operation in the country Environment Bay of Plenty are taking strong lake ecosystems. Through better – has recently been sentenced on 34 counts action to penalise those that do not take knowledge of these threats and of contaminating the environment. This has their environmental stewardship seriously. ways to manage them, improved highlighted issues around what people can Councils prefer to work alongside farmers in methods for lake restoration can and can not do on their land. Allan Crafer, an educational role to ensure that farmers are be developed a principal of CraFarms, maintains that they complying with the RMA. But for the minority have been unfairly targeted by Councils, the that continue to fl out the rules that are now - New models and technologies Resource Management Act, and the media, protecting our environment, the Councils are to effectively manage harmful whilst doing a good job of increasing their using penalties. algal blooms production and enlarging their empire for the It is therefore diffi cult to have any sympathy benefi t of New Zealand. - New pest fi sh management and for people like the CraFarm Group. Dairy control technologies Many farmers are now operating their farms farming is a business that has impact on - A city retrofi t model under best management practices that the environment and it is essential that minimize their environmental impact. The stewardship of the land is treated with respect. For more information on recent global market, Fonterra, central and local Most dairy farmers recognise this, and there LERNZ activities, please visit: Government agencies, and the New Zealand are plenty of farmers out there now proving www.lernz.co.nz public, are now demanding that we have a that profi t and minimal environmental impact clean, green image. can go hand in hand.

LakesNews Issue No.1 October 2009

Whoops … slipped out the gate

The owner of these cattle had not deliberately infringed. Nonetheless, all stock owners should be mindful that the grazing of lake margins is not a permitted activity under the Water and Land Plan (ref. Rule 8 – Stock Exclusion from Lake Rotoiti. Urine is a major source of nitrogen that easily leaches into groundwater. Dung also has high nitrogen and phosphorus concentrations. Livestock are fi ve times more likely to urinate and defecate when standing in water than on land, releasing large quantities of nutrients directly into the water.

Contacts for the Lakeswater Quality Society Incorporated • Chairperson - John Green, Phone 07 362 4204 • Secretary - Ann Green, Phone 07 362 4204 • Treasurer - Brentleigh Bond, Phone 07 362 4700 • Newsletter - Warren Webber, Phone 07 362 4933, email : [email protected]