It's been a while since we've looked at this, but my recollection is that in 2010, when we did look at it, we saw recognized standards from the World Meteorological Organization for well-designed water monitoring systems. I guess they look at the parameters, but they look at the geography and the parameters that need to be monitored and give guidelines for coverage and so on.
So there are standards. I think there are some at the United States Geological Survey as well. They have a sort of model too.