Search all sites near me now
Search your favourite swimming spots

  • Why this status?

    Click here for detailed information on water quality monitoring

    The science

    Summer season monitoring

    LAWA shows the best available water quality information to help you decide where to swim.

    Special Status

    Special StatusIssued: 02 Dec 2024

    Unsuitable for swimming.

    This site has temporarily been determined as unsuitable for swimming, and we recommend people do not swim at this site.

    Issued 2 December 2024: Health Warning – Algal Bloom in Lake Pegasus

    Te Mana Ora | Community and Public Health has issued a health warning after potentially toxic blue-green algae (planktonic cyanobacteria) was found in Lake Pegasus.

    People should avoid the Lake and animals, particularly dogs, should not be allowed near the water until the health warning has been lifted.

    The type of cyanobacteria that is currently present is Tolypothrix which can be present as discolored water or as scums floating in the water column or form surface scums or sheens. The colour can be brown, green, or blue-green.

    Dr Cheryl Brunton, Medical Officer of Health of Te Mana Ora, National Public Health Service, says the algal bloom can produce toxins harmful to humans and animals.

    “People should avoid contact with the water until further notice.”

    “Exposure may cause skin rashes, nausea, stomach cramps, tingling and numbness around the mouth and fingertips. If you experience any of these symptoms visit your doctor immediately and please let your doctor know if you have had contact with the lake water”, Dr Brunton says.

    No one should drink the water from the lake at any time. Boiling the water does not remove the toxin.

    Animals that show signs of illness after coming into contact with algal mats or scums should be taken to a vet immediately.

    Fish and shellfish can concentrate toxins and their consumption should be avoided. If fish are eaten, remove the gut and liver and wash in clean water.

    Further information on gathering Mahinga Kai can be obtained below.

    “When a bloom of potentially toxic cyanobacteria is present in a lake, there is a possibility of cyanobacteria and toxins being transported downstream.

    “People are advised to avoid contact with the downstream water bodies,” says Dr Brunton.

    Environment Canterbury monitors the lake weekly during summer and the public will be advised of any changes in water quality that are of public health significance.

    Warning(s) to avoid the following waterway(s) due to ongoing algal blooms is/are still in place.

    Facts about cyanobacteria

    • Cyanobacteria occur naturally but can increase rapidly during warmer months.
    • Algal blooms are caused by a combination of nutrients in the water (such as nitrogen and phosphorus), and favourable weather conditions (e.g., increased temperature, calm days).
    • If the water is cloudy, discoloured, or has small globules suspended in it, avoid all contact.
    • Not all cyanobacterial blooms are visible to the naked eye and toxins can persist after the blooms disappear.
    • Cyanobacterial concentrations can change quickly with changing environmental conditions (e.g., wind). If a health warning is in place avoid contact with the water.

    For further details visit: www.lawa.org.nz/explore-data/canterbury-region/

    Or contact Te Mana Ora on (03) 364 1777:

    www.cph.co.nz/your-health/recreational-water/

    For more information about Mahinga Kai:

    www.cph.co.nz/wp-content/uploads/saf0112.pdf

     

    Reminder

    Heavy rain flushes contaminants from urban and rural land into waterways and we advise you not to swim for 2 – 3 days after heavy or prolonged rain – even at sites that generally have good water quality. Check that the water is clean and clear before taking a dip.

    Toxic algae can rapidly bloom to harmful levels, and not all freshwater sites are monitored for toxic algae. Play it safe — if you can see toxic algal blooms in rivers or lakes, avoid contact or choose another site to swim.

    Summer season monitoring history

    • Samples this season
    • Samples from last 5 years
    E. coli sampling graph
    • View as graph
    • View as donut

    What do the monitoring results mean?

    Suitable for swimming – The monitoring result met national water quality guidelines at the time of testing.
    Caution advised – The monitoring result for E. coli was slightly elevated at the time of testing. Water quality generally suitable for swimming, but young children, elderly or those with compromised health may be at increased risk of illness.
    For sites where toxic algae is routinely monitored, the monitoring result exceeded the surveillance criteria. Avoid contact where toxic algae is present.
    Unsuitable for swimming – The monitoring result did not meet the national guidelines at the time of testing.
    For sites where toxic algae is routinely monitored, the monitoring result exceeded the alert level criteria. Avoid contact with the water and with toxic algae along the edge of the water.

    Long-term grade information

    Long-term grade based on five years of data
    Minimum data points required 50 Highest E. coli per 100ml value {{riskData.maxValue | number:0}}
    Number of data points available {{riskData.dataPoints | number:0}} Lowest E. coli per 100ml value {{riskData.minValue | number:0}}
    Hazen 95th percentile result {{riskData.hazenResult}} Long-term grade
    {{riskData.rating}}

    What do the long-term grade icons mean?

    Excellent – The estimated risk of Campylobacter infection has a <0.1% occurrence, 95% of the time.
    95th percentile of E. coli / 100 mL is <= 130.
    Good – The estimated risk of Campylobacter infection has a 0.1 - 1% occurrence, 95% of the time.
    95th percentile of E. coli / 100 mL is > 130 and <= 260.
    Fair – The estimated risk of Campylobacter infection has a 1 - 5% occurrence, 95% of the time.
    95th percentile of E. coli / 100 mL is > 260 and <= 540.
    National bottom line: 95th percentile: 540
    Poor – The estimated risk of Campylobacter infection has a >5% occurrence, at least 5% of the time.
    95th percentile of E. coli / 100 mL is > 540.
    Not available – There were not enough data to determine the long-term grade at this site.

    Learn more

    See factsheets for more information.

     Download data

  • What about my dog?

    Information about toxic algae

    Dog owners

    Keeping your dog safe and healthy this summer

    A trip to a lake is a lot of fun and knowing how to keep your dog safe means you are able to relax and enjoy the adventure even more. Toxic algae can be harmful to dogs (and us) – this section shows you what to look for.

     Planktonic bloom

     

    What to do

    • The best thing you can do to keep yourself, your kids and your dog safe is to know what toxic algae looks like and avoid it. 

    • If you are not sure, keep your dog on a lead at a lake and don’t let them in or near the water. Bring water from home for your dog so that they don’t need to drink out of the lake.

    What is toxic algae?

    Toxic algae, known scientifically as cyanobacteria, are naturally occurring in rivers and lakes in New Zealand, including waterways with good water quality. Most of the year it is present in lakes at low levels that are not much of a danger. But algae can be a problem during the summer months, when warm temperatures and nutrients in the lake create an environment where it can thrive, forming extensive blooms which can be toxic to humans, dogs, livestock and wildlife. 

    Scientists do not yet understand when and why this algae turns toxic, so to be safe, always treat it as toxic.

    Dogs are particularly susceptible to poisoning from toxic algae as they may drink lake water or play in the water. 

    What to look for

    Toxic algae grows within the water column in lakes and cause the water to become murky or cloudy. 

    These free floating algae blooms in lakes are generally green in colour and can look like paint, petrol or pea soup. It can also form foam or scum on the water’s surface, especially at the water’s edge. Sometimes blooms may not be very visible.

    Council staff monitor for toxic algae in lakes where blooms are known to occur. Blooms can occur very suddenly (within an hour) so please alert your regional or unitary council if you notice a new algal bloom in a lake.

    What if my dog has eaten toxic algae?

    If you suspect that your dog has eaten toxic algae, you should contact your vet as soon as possible. Signs a dog has been poisoned by toxic algae include lethargy, muscle tremors, fast breathing, twitching, paralysis and convulsions.

    Find out more about toxic algae here

  • What's at this site?

    Find out all recreational activities and facilities at this site

    Activities & facilities

    Site suitable for these activities and has these facilities

    Our lakes, rivers, and beaches are great natural playgrounds but they can be unpredictable.  Be aware of other potential risks such as rips, strong currents, sudden drop offs, or underwater objects before jumping in.  LAWA recommends that you avoid swimming for 2 - 3 days after heavy rainfall and follow the advice of any warning signs in place.

    Activities

    Swimming
    Dog walking

    To find out when and where you can exercise your dog please refer to your local authority.

    View exercise areas

    Fishing
    Check the rules
    Boating
    Walking

    Facilities

    Picnic area
    Public transport

How do I get there?

Pegasus Lake
Open in Maps

Latest news and stories

Upcoming events