Dear Editor

I would like to add my two bob to the Richardson Road Reservoir debate.

I have been a keen observer of the reservoir over the past ten years by way of its capacity to reduce nagging to a tolerable level. Grab the fishing rod and a couple of stubbies and watch the float jiggle as the trout play with the hook while surrounded by an absolute Tasmanian  diamond. I sat on the wall one day while a platypus and  two pups swam at my feet. I blinked, they crash dived and came up for air about 30 meters away.

Those pups would now be teenagers and like most teenagers they should have been strangled at birth because I reckon they are the cheeky little buggers that have vandalised and breached the wall. They have reduced their idyllic home to a mud puddle and the eight or ten that used to be the dam clan are now living rough on the street God knows where. It is harder to feel sorry for the smartaleck trout who for the most part ignored hundreds of dollars worth of fishing gear over the years.

When there is a heavy rain event two creeks feed directly into the reservoir and meet at a 90° angle. This sets up a turbulent vortex motion across the water surface. The dam rises and spills and the hundreds of tonnes of silt gets a buffing but remains in place behind the wall. The St Marys Rivulet runs cloudy for a while then cleans up soon after.

The thing that worries me is what would happen to all this accumulated silt if there was a catastrophic failure around the already breached wall or worse still if some wet behind the ears engineer/economic genius was to have the wall removed. I reckon a large sharp rain event would see all this silt arranging its sticky, stinking, toxic mass on or about the flood level of the St Marys Rivulet in the  middle of town.

The silt is made up of rotted eucalypt material, rotted  water weeds and some mineral matter carried up to and retained in situ by the wall. The anaerobic mass will be highly acidic, loaded with tannins and if allowed to move en mass down the system it will suck the life out of everything it contacts. The food chain downstream will cease to exist until the silt dilutes and the poor bloody platypus are going to cop it again.

Simply draining the dam is not a solution. The 30cm plughole will be overwhelmed by inflow in a rain event and will quickly block with sticks and leaves. The two breaches around the wall are both in areas of earth fill and will rapidly scour out and the silt will begin to move.

There is a serious environmental problem here caused by humans in building the dam. Ignoring this and buck-passing are unlikely to solve the potential for disaster. Someone needs to take responsibility and sort this out real soon.

A short term fix would be to pump some concrete into the platypus burrows and see if the pesky little buggers can dig through that. The right thing to do would be to de-silt the dam, fix the wall (which looks like it was built by the same bloke who made the nuclear bomb proof missile silos) and turn it back into the absolutely sensational gem that it has been for the past fifty years or so.

Bob Oates, St Marys