As unfortunate as it is for the pets involved -- I'm really thinking this "blue algae problem" is more a problem of lack of education on basic survival skills (which is problem that seems to be very prevalent in urban areas).
Might just be me and the pictures I'm seeing, but almost all the pictures I've seen leave me wondering why anyone would enter water that looks like that, much drink from it or let their pets drink from it. The lack of clarity and overall color make it seem pretty evident that the water has a tremendous amount of microbial life in it, which would imply it's a high-risk water source for consumption (and possibly even entry depending on lack of clarity and duration of being in the water).
So I'm rather befuddled as to why this would even be an issue -- unless it just comes back to lack of a relatively basic survival education and applying it to pets/livestock.
Actually this confusion reminding me of the first time I saw that a zoo had exhibits with basic farm animals (e.g. chickens, cows, pigs, horses)..... animals I've previously thought everyone would already know and recognize, but it turns out that's apparently not the case. That of course reminds me of a (sadly) amusing freakout I've heard of by a late-teen/young adult who was seeing a cow for the first time in their life (their entire life had been spent in Los Angeles). It almost cause the coworker (whose neive was visiting from LA) to have a wreck as they were driving along and she started screaming and freaking out wanting to know what the animals were she was seeing.....and it was nothing more than one of the many (small) herds of cattle in this area.
