the selwyn can be thought of as a bit of a ground yaar local councilor and freshwater ecologist lan phamd by excess nutrients from fertilizers. lan: there's a toxic cyanobacteria warning for this site and actually two other sites on the selwyn as well. actually, this is just a patch of it. yaara: right, it's the black stuff on the rocks. lan: yeah, so it appears as kind of these quite thick, almost velvety, mats. yaara: you can't swim here. this algae is toxic and can harm people and animals who come into contact with it. lan: and it just takes one teaspoon for a dog to ingest that for it to actually die. when you have excessive nutrients and sediments coming into the system, these blooms can really take off. and that's really sort of the perfect storm of what we've gohere. and so it really provides, like, this, essentially, a wonderland for 4 million blooms and they have taken off here this summer as they often do in recent history. yaara: yeah, which is really unfortunate in summer, 'cause that's when families wanna come to rivers. lan: oh, it's hugely disappointing. it just fuels this