The author comes to a conditional conclusion: if a recent trend in water pollution levels continues, then the issue of water pollution will stop getting worse. The trend the author cites in support is that the rate at which water pollution is increasing is leveling off. We can see this by comparing this year's and last year's water pollution: both years generated almost the same amount.

When thinking about the argument's flaw, remember that the conclusion is a conditional statement. We're looking for a flaw in the claim that water pollution will stop getting worse if the rate of pollution truly stops increasing. So we have to think of other factors that might interfere: even if the rate of pollution stays stable from now on, how might it be possible that the problem of water pollution will still get worse?

One oversight in the argument is that new pollution might worsen the effects of existing pollution. Even if the rate of pollution stops increasing, that still leaves us with a fixed amount of new pollution generated each year. If those annual amounts of pollution compound with each other, the overall problem could still keep getting worse. Another oversight is that pollution may not all be equally toxic, so if the type of water pollution is getting worse, that could continue to worsen the water pollution problem.