It's a rainy Sunday morning and it's pouring down outside as I write this - everything is getting a really good soaking.

This is great news for our gardens and street trees - but not so good for the poor old Yarra River. Tomorrow, when Yarra Watch measure the contamination in the river, they'll find higher levels of toxins and bacteria than before the rain.

Everyone knows that the Yarra is sick, we've all heard about the kayakers with leptospirosis and the dead eels, but why? No doubt part of the problem is fertilizers and animal poo from farms in the Upper Yarra, or more disturbingly; businesses like Amcor Packaging in Abbotsford who illegally wash toxins into the river, but I can't just blame other people for the problem. The sad fact is that a large part of the pollution is from neighbourhoods like ours, on nice wet days like today.

As I write this, all that rainwater is running over the road, and the footpaths, and down the gutter to the stormwater pits. On the way the rainwater is picking up pollutants from the surface - including petrochemicals, oils, rubbish, dog poo, detergents and organic matter, which are washed into the drains by the water. By this afternoon, all of that water and pollution is going to end up in the Yarra River. (For a more comprehensive listof pollutants and their effects click here).

So what can we do? On an individual level - not a hell of a lot. We can pick up litter, wash the car in a carwash, and report anyone putting anything nasty where it will end up in the drains. As a neighbourhood however, we can do a lot.

Basically, the best thing we can do is retain and use as much of the water here in our neighbourhood as possible, and then make sure the water that ends up in the stormwater system is clean before it gets to the Yarra.

I've got a couple of ideas on how we could apply some water sensitive urban design measure here in our neighbourhood, I'll draw them up and post them shortly.

The photo above left is one of the stormwater pits in our neighbourhood, taken today during a brief hiatus in the rainfall. Click image to see larger