US water utilities contribution to PWS systems

I am still stopped in the middle of a rope pulled to the right by the advantages and to the left by the disadvantages, and staring at both sides. And still I would not know if the payments for the watershed services (PWS) are a good or a bad strategy. In any case, and on line with the interesting post written by Donna Vincent some days ago (https://water.tallyfox.com/groups/value-water/blog/water-utilities-own-value-water-equation), I found an article about the engagement of US water utilities into different PWS programmes (http://www.sciencedirect.com.sciencedirect.han.technikum-wien.at/science/article/pii/S2212041614000059), which seem to show the positive repercussion of their participation (not only on the water system efficiency and management, but on the environmental status of the watershed).

I was just wondering that if water utilities (and we are not discriminating between private or public ones) needs to pay for the equipment maintenance, cleaning, repairing, chemicals supply, etc. why not to pay for those other type of services… However, I am still confused. If riparian shading, for example, helps to steady the water temperature, and therefore, it represents a saving in the final costs of the treatment for example, what would PWS mean in this context? Are the water utilities going to pay to the trees for growing? or to their "owners" (whoever they are, common goods, private properties…)? If this last, the concept of PWS could be a bit tricky. It sounds like if everyone who is not throwing stones against the windows of a company must to be paid, since this would reduce the maintenance costs. Or anyone who is taking the bus instead of the car needs to be paid because he, or she, is reducing the CO2 emissions... So, should we pay or should we regulate or should we educate? How necessary is taking the risk of causing a higher water and ecosystem commodification in order to avoid a long term solution based of the awareness?

On the other side, the environmental and water preservation and their sustainable management have associated costs and benefits; so how to deal with this? Should the companies pay for the environmental maintenance in the same way as they do with the rest of their equipment and infrastructures? Is so, how can these processes be regulated and assessed? Or what would the alternatives be? So, I am still in the middle of the rope, staring at both sides…