Hope you aren't trying to do a paper on that.
There are too many other factors affecting business to try and blame it on the water. The economy began its down-turn back then, first with the dot-com collapse, and later with the drops in the stock market. Businesses on the edge just couldn't keep up with all that pressure.
Also, who says (authoritative source?) that the water quality is 'bad'? Is the vis down because the water quantity is down? This can be the drought, as a cause. The visibility is worse because the same particles are now condensed into less water.
Bottom line: Neither the cause, nor effect, nor premise are logically sound.