Penny Gaylor: Helpful information about algae in water ways

Penny Gaylor.

Weekly column by Kāpiti's Greater Wellington Regional Council representative Penny Gaylor.

It's summer - possibly, but there is a high chance of blooming algae in our Kāpiti Coast rivers, and even the possibility of a repeat of last summer's toxic algae.

So here is some information on what we can all be looking out for as we chill, swim, walk, bike, or whatever, in and around our water ways this summer.

It's really important to be mindful of the risk of toxic algae to humans getting sick from swimming in waterways affected by the toxic version, and the potential deadly risk to our dogs.

It turns out that freshwater toxic algae (cyanobacteria) is naturally present in all New Zealand waterways. Usually, toxic algae forms dense blooms when the weather is dry and warm.

Algal blooms can be dangerous to aquatic life in our rivers and streams by blocking sunlight and smothering the riverbed.

The bloom will usually last until there is a 'flushing event'. Flushing events happen after heavy rain, washing the algae away. Once the algae reaches the sea, it is no longer harmful as the salt water de-activates the toxins which affect humans and dogs.

Swallowing water containing toxic algae can make people sick, and contact can cause irritation of the skin, eyes, nose and mouth.

Dogs are most at risk as they like the smell and taste of toxic algae. A small amount, the size of a 50 cent piece, can be enough to kill a dog. Dogs are most susceptible when algae mats wash up along river edges.

How can I best describe what it looks like? In rivers it's a black, green, brown slime on rocks, or brown or black 'mats' at the river's edge that have a velvety texture and earthy/musty smell. Check for warning signs before getting in the water or allowing your dog near it.

Check for alerts before you go to a river, look for warning signs put up by either KCDC or GWRC, and keep an eye on your dog when you're there.