What's happening with Lake Hayes?

We know how much you love Lake Hayes. 

The quality of it’s water affects recreation and business activities. 

We want to help people understand, connect with and work together to improve the lake’s water. 

There are two main issues we need to address:
(1) Short-term clean up (remediation) from past industry and farming practices
(2) Long-term care and management of the catchment to make sure our current activities aren't deteriorating water quality any further. 

Here we provide information on three different methods that could be useful to help clean up the lake. Each approach has different mechanisms, costs, side-effects and likelihoods of success that need to be considered.

We know how much you love Lake Hayes

The quality of its water affects recreation and business activities.

We want to help people understand, connect with and work together to improve the lake’s water.

We'll use this page to let you know what we are doing to monitor and protect this iconic lake.

There are two main issues we need to address:

  1. Short-term clean up (remediation) from past industry and farming practices
  2. Long-term care and management of the catchment to make sure our current activities aren't deteriorating water quality any further.

We’re working on a number of activities to understand

We know how much you love Lake Hayes

The quality of its water affects recreation and business activities.

We want to help people understand, connect with and work together to improve the lake’s water.

We'll use this page to let you know what we are doing to monitor and protect this iconic lake.

There are two main issues we need to address:

  1. Short-term clean up (remediation) from past industry and farming practices
  2. Long-term care and management of the catchment to make sure our current activities aren't deteriorating water quality any further.

We’re working on a number of activities to understand the current state of the water quality and the best ways to help clean up the lake.

What's happening with Lake Hayes?

The key activities we are working on are:

  • Monitoring of overall lake health - measuring the Trophic Level Index
  • Installing a lake monitoring buoy on Lake Hayes
  • Measuring clarity (turbidity) at Mill Creek
  • Monitoring the lake’s suitability for swimming (contact recreation)
  • Catchment studies
  • Investigating possible remediation methods

Please see the “What’s happening” tab below for more information on each of these activities.

Methods for Remediation

We are still researching different methods that could be used to remediate the lake. We have three preferred methods at the moment, and are currently looking at case studies of how these have worked for other lakes.

We want to involve you in the decisions, so as these reports are released later in 2018 we’ll share the information with you and ask for your views.

There will also be plenty of time for you to have your say - either by writing comments here in this portal, or attending community meetings/drop-in sessions.

We’ll update this page as the project progresses. Please sign up for updates by registering on the “Stay Informed” panel on the right of this page.

Discussions: All (5) Open (5)
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    Tli data for lake hayes

    What is the Trophic Level Index?

    The Trophic Level Index (TLI) is used to give an overall picture of the health of New Zealand lakes. 

    Each lake is assigned a number between 1 and 7.  1 being the highest ranking for the best water quality and 7 being the lowest.  

    The Trophic Level Index measures four important factors:

    1. Water clarity
    2. Chlorophyll content
    3. Total phosphorus
    4. Total nitrogen

    Why is measuring TLI important?

    The lower the number, the better the water quality in the...

    What is the Trophic Level Index?

    The Trophic Level Index (TLI) is used to give an overall picture of the health of New Zealand lakes. 

    Each lake is assigned a number between 1 and 7.  1 being the highest ranking for the best water quality and 7 being the lowest.  

    The Trophic Level Index measures four important factors:

    1. Water clarity
    2. Chlorophyll content
    3. Total phosphorus
    4. Total nitrogen

    Why is measuring TLI important?

    The lower the number, the better the water quality in the lake, so the TLI is an important indicator of how healthy the lake is. 

    Conversely, the higher the value, the greater the nutrients and fertility of the water, which encourages growth, including algal blooms.

    Want more information about TLI? Check out the factsheet here

    What is the TLI for Lake Hayes?

    LAWA (Land, Air, Water Aotearoa) has been measuring the Trophic Lake Index for Lake Hayes since 2005. Here's what that data looks like: 


    Here's some important information about what the different coloured data points mean. 

    With a TLI in the range 4 - 5, Lake Hayes is currently rated as having poor water quality. LAWA have scored this lake as Eutrophic.

    Eutrophic lakes have an abundance of nutrients that support a dense growth of algae and other organisms. When these die, their decay reduces oxygen in the shallow waters in summer. This means Lake Hayes is likely to be green and murky, with higher amounts of nutrients and algae in some areas of the lake. 

    You can also go to the LAWA website for Lake Hayes to view the data.

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    Limnotrack monitoring buoy


    Lake Hayes will be the first lake in Otago to have a monitoring buoy installed. 

    Installation is scheduled prior to the summer 18/19 season.


    What is a lake monitoring buoy?

    A lake monitoring buoy is an autonomous, solar-powered water quality monitoring system.

    It has two parts: 

    1. A weather station mounted above the water 

    2. A water quality sensor package, which uses an electric winch and armoured data cable to raise and lower the sensors throughout the water column



    What do lake buoys measure?

    ...


    Lake Hayes will be the first lake in Otago to have a monitoring buoy installed. 

    Installation is scheduled prior to the summer 18/19 season.


    What is a lake monitoring buoy?

    A lake monitoring buoy is an autonomous, solar-powered water quality monitoring system.

    It has two parts: 

    1. A weather station mounted above the water 

    2. A water quality sensor package, which uses an electric winch and armoured data cable to raise and lower the sensors throughout the water column



    What do lake buoys measure?

    1.  The top mounted weather station measures data related to climate and weather, including:

    • wind speed and direction
    • air temperature
    • solar radiation
    • relative humidity 
    • barometric pressure
    • rainfall

    2. The winch-operated sensors move up and down the water column collating data related to water quality, including:

    • Water temperature 
    • Dissolved oxygen 
    • Chlorophyll fluorescence 
    • Phycocyanin fluorescence
    • Turbidity (to detect sediment)
    • pH
    • Conductivity 

    Here is a schematic diagram of how the various components of a typical lake monitoring buoy work.



    Why is monitoring important for Lake Hayes?

    It helps us track changes in water quality. These changes can vary from seasons to minutes. Monthly or seasonal monitoring is not usually sensitive enough to detect these changes. 

    Data will be collected every 15 minutes. This high-frequency data will enable Otago Regional Council scientists to better understand processes that affect the health of Lake Hayes. 

    Soon we will have very accurate data on temperature and formation of thermal layers (stratisfication), oxygen depletion (especially from water near the bottom), algal species, sediment and water clarity.

    This data will greatly improve our understanding of how Lake Hayes is responding to the environment in both the short and long-term. This detailed data and will give us a clearer picture of what is happening in the lake - so we can make better decisions about remediation. 

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    Turbidity

    What is turbidity?

    Turbidity is the cloudiness or haziness of the water and is a key measure of water quality. 

    Water can contain particles of many different sizes, which are usually invisible to the naked eye.


    Why is measuring turbidity important?

    Turbidity can be caused by growth of phytoplankton or high sediment levels from construction and agriculture. Other activities affect turbidity too, like sediment entering the lakes during wet weather.

    In lakes, high turbidity levels can reduce the amount of light reaching lower depths, which can inhibit growth of aquatic plants and consequently affect species which are...

    What is turbidity?

    Turbidity is the cloudiness or haziness of the water and is a key measure of water quality. 

    Water can contain particles of many different sizes, which are usually invisible to the naked eye.


    Why is measuring turbidity important?

    Turbidity can be caused by growth of phytoplankton or high sediment levels from construction and agriculture. Other activities affect turbidity too, like sediment entering the lakes during wet weather.

    In lakes, high turbidity levels can reduce the amount of light reaching lower depths, which can inhibit growth of aquatic plants and consequently affect species which are dependent on them, like fish. 

    We've started measuring turbidity in Mill Creek, near Lake Hayes

    Mill Creek is the primary inflow running into Lake Hayes. 

    We are measuring turbidity so we can see how much sediment is coming into Lake Hayes from Mill Creek as that will have impact on the water quality in the lake. 

    At the end of August 2018, we installed a turbidimeter to measure turbidity every 30 minutes at Mill Creek. Below is a snapshot of early data. 


    Data is being measured every 30 minutes every day, and updated in real time. 

    Click here to see the latest measurements. 
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    Bacterial risk   swimming at lake hayes

    Can we swim in Lake Hayes?

    Lake Hayes is monitored during the summer months, with information published on the LAWA (Land, Air, Water Aotearoa) website.

    To check if the lake is safe for swimming, the levels of the bacteria E. coli are measured. 

    This graph shows the overall risk grades for the last three summers - 2015/16, 2016/17 and 2017/18. 

     

    Two new monitoring sites for 18/19 season

    We think the E. coli monitoring site may be too close to the resident duck population, which is skewing the test results. 

    We also know this...

    Can we swim in Lake Hayes?

    Lake Hayes is monitored during the summer months, with information published on the LAWA (Land, Air, Water Aotearoa) website.

    To check if the lake is safe for swimming, the levels of the bacteria E. coli are measured. 

    This graph shows the overall risk grades for the last three summers - 2015/16, 2016/17 and 2017/18. 

     

    Two new monitoring sites for 18/19 season

    We think the E. coli monitoring site may be too close to the resident duck population, which is skewing the test results. 

    We also know this is a popular spot for tourists to feed the ducks. 

    This means that the very high E. coli readings in the summer of 2018 are not likely to be representative of bacterial count in the whole lake. 

    This is why we’re installing two more E. coli monitoring sites at other points in Lake Hayes. 


    Where is the most up-to-date information?


    Once monitoring starts (usually December - March), LAWA regularly updates the data to show the latest water quality results for Lake Hayes. 

    You can find this here

    You'll also find information for dog owners and what facilities are available, and other helpful information about Lake Hayes. 

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    Lake hayes catchmentlawa.jpg

    Where is the Lake Hayes Catchment?

    The Lake Hayes Catchment water management zone covers an area of 4271 hectares.

    Excessive amounts of nitrogen (N) and phosphorous (P) can cause water quality issues, particularly in lakes. 

    To find out where the nutrients are coming from, we need to study key water bodies (creeks and streams) throughout the whole area surrounding Lake Hayes. 

    Historically most P is associated with sediment from bed/bank erosion into Mill Creek.

    It’s important to study how much sediment and phosphorous enters Mill Creek, because it is the...

    Where is the Lake Hayes Catchment?

    The Lake Hayes Catchment water management zone covers an area of 4271 hectares.

    Excessive amounts of nitrogen (N) and phosphorous (P) can cause water quality issues, particularly in lakes. 

    To find out where the nutrients are coming from, we need to study key water bodies (creeks and streams) throughout the whole area surrounding Lake Hayes. 

    Historically most P is associated with sediment from bed/bank erosion into Mill Creek.

    It’s important to study how much sediment and phosphorous enters Mill Creek, because it is the major inflow into Lake Hayes. 

    However in recent years, there may have been surface water run-off from bare land that was exposed during the earthworks during the building of resorts and homes. 

    We have already seen some evidence of this because N is known to be elevated in Mill Creek, and also in some springs in the catchment - but we need to recheck to be sure.

    Why are we doing a new study and what will it tell us?

    We want to measure the main source of N & P in the Lake Hayes catchment. 

    Once we know where the highest concentrations of these nutrients are, we can take steps to prevent them diffusing into the water.

    How will it work?

    We have selected eight surface water sites and one groundwater site at different places around the Lake Hayes catchment.

    The sites are the same as those previously studied in 1997 by an ORC scientist.

    We will install water flow meters and, depending upon the type of testing, either collect water samples continuously or monthly. 

    Since we have good data that was collected in 1997, we will be able to make some comparisons between the current state and over 20 years ago, i.e. then and now. 

    Other data

    We will also measure turbidity (cloudiness) and what happens in high flow events like storms. 


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