The editorial in the newspaper does not show the main point very well, because so many "but" are used inside. These many transitional hedging words lead the readers apart from the main idea, while the first sentence fail to show the facts, either. So I think the first sentence is just for showing the current state of the residents there, then what is supposed to be done by them is shown later, and the future outlook is stated finally.
The first sentence should be changed to "At present, Mason City residents always use the nearby Mason River for all kinds of recreational activity, according to surveys of the region's residents consistently rank water sports (swimming, fishing, and boating) as a favorite form of recreation.", because the current situation is the base of all the other facts and statements and it have to agree with the surveys.
After that, it should be stated that residents must be avoiding the river because of the low quality. And it can also be shown as "several residents has already found that fact", rather than "residents must be avoiding the river because they think that it is not clean enough", which disagrees with "consistently rank water sports", the consequence of the survey from the residents.The facts themselves must not be disagreeable.
Finally, the future of Mason River and the life of residents are to be told to readers, just as what is done in the original editorial. But a final warning of the use of Mason River for the time being is highly suggested, for it is more important to the life of those residents.
In all, this editorial does not state out its main idea very properly. And at the same time, there are some contradictions inside of it because of the wrong analysis of the survey. It shall be redone as "facts", "warnings" and "futures".