It is entirely true that we don’t want rivers of shit to be added to our, err, rivers. That is one of the things that we have water companies for, to make an attempt at preventing this.
It’s also true that at some point, or some times, we do want to have rivers of shit joining our rivers. Because the costs of not having them are greater than the benefits we gain by their absence.
True, we can all argue about those costs and benefits. Those who like swimming in wild waters might place a greater value on the absence of turds than those who have to pay for the clean up but who live in a different watershed. The allocation of costs and benefits will change valuations, most assuredly.
And yet the base problem remains:
Even in the wake of the sentence last week, under which Southern Water was fined £90m, the company’s own maps show a continued flow of raw filth into coastal waters. Same shit, different day. The only occasions on which water companies are allowed by law to release raw sewage are when “exceptional rainfall” overwhelms their treatment works. But the crap keeps coming, rain or no rain.
We all agree than that exceptional rainfall – or other exceptional circumstances perhaps – allow the discharges. Again, we can then argue about what the meaning of “exceptional” is but we all do agree, at least I think we do, that if Noah’s Ark starts to look like something we’ll regret not having built then we’re going to be happy enough that we didn’t overbuild of sewage plants so as to not leak at this point. A once in 8 thousand years event would be over-engineering to a ridiculous extent.
So the pass is sold, the principle accepted. Now all we’ve got to do is define when?
Well, that’s a simple enough problem, we’re looking for the optimal result. Which is when the costs of prevention are about the same as the damages from non-prevention. We can get fairly fancy and add in probability if we wish. But that is about where the line is. The costs of preventing this happening are such and such, the damages avoided by spending this are so, we spend to prevent until such and such equals so.
So, what are the costs of rivers of shit in our rivers? What are the costs of preventing them?
And no, we don’t want to spend more than is saved – that merely makes us poorer.