Recreational water quality – is it safe to swim?

Kāpiti has many places that are popular for swimming and other activities. Keeping yourself up to date on our recreational water quality is important.

Monitoring water quality | Advice for swimmers | Toxic algae (cyanobacteria) in rivers and streams | Keep updated | Latest recreational water quality results

Monitoring water quality

Every summer we support Greater Wellington Regional Council to regularly monitor our swimming sites. We help by collecting samples at our recreational river sites and 14 coast sites help support the information available year-round on LAWA’s website. This is the best way we can check if the water quality at your favourite spot is suitable for swimming. You can find out more about water quality monitoring from Greater Wellington’s Our monitoring programme.

Kāpiti’s water quality is generally safe for swimming and other water-based recreational activities, but there's a few things to think about before you jump in.

Advice for swimmers

In summer there's less water flow and rain to flush rivers of bacteria such as toxic algae.

Some good things to remember:

wait 48 hours after rain before swimming; heavy rain flushes bacteria and contaminants into our waterways, making water quality unsuitable for swimming
don't swim in streams or at stream- and rivermouths during hot summer months
keep out of any water that's murky or smells unpleasant
avoid swimming near storm water outlets on our beaches, or other possible sources of contamination
check for hazards such as strong currents, tidal rips, or steep drop offs
know your limits, and never swim alone
always keep small children within arm’s length.

We'll only put up signs if there's an unacceptable health risk from swimming in the water.

Toxic algae (cyanobacteria) in rivers and streams

Toxic algae in our rivers aren't actually algae at all but cyanobacteria, which are commonly known as blue-green algae. Cyanobacteria are naturally present in many of Aotearoa New Zealand's lakes and rivers. Lots of types of algae and cyanobacteria grow in our waterways so it's important to know which ones are harmful.

Toxic algae can cause issues in the Waikanae and Ōtaki rivers during summer, especially when large amounts form mats that rest on riverbanks. These blooms usually last until heavy rain can flush it through.

Make sure you're aware of any increased risk, especially if you've whānau who are very young, very old, or who have vulnerable health.

One of the most important things you can do before heading out for a swim is to check LAWA's interactive map for water quality at different sites.

Spotting toxic algae

Dogs are most at risk, partly because they love the smell and taste of toxic algae. Even a small amount can be fatal – never let your furry friend scavenge at the river’s edge.

Keep an eye out for:

brown or black velvety mats growing on rocks in the riverbed
mats that have come loose from the riverbed; these can wash up on river banks or forming floating ‘rafts’ in shallow areas
dried out mats on the riverbank; these turn a light brown or white colour and may also produce a strong musty odour.

If you see toxic algae, be cautious and avoid that river site, particularly if you have a dog.

For more information, see Greater Wellington’s Toxic algae.

Keep updated

This summer, before you swim:

check the LAWA website for live updates on where it’s suitable to swim
follow our social media channels and Antenno app for updates on where there’s toxic algae, so you can make an informed decision about where to swim and take your dogs.

We have new signs for toxic algae at our Ōtaki River and Waikanae River at Old SH1 sites, to show you the current risk level and what you should do. Keep an eye out for them!