There were quite a few mitigation projects and things like stream and wetlands restoration are part of it. Quite a few ponding systems were installed in my neck of the woods. I live on the banks of a main tributary into the Chesapeake that also supplies the drinking water for the metro area. The whole thing was kicked off by EPA regulations specific to the Chesapeake watershed.
It’s really all quite boring. Taxes are a part of life in a metropolitan complex.
I have a simpler - albeit uglier method of collecting and using rainwater. I bought several big grey plastic garbage cans that I placed at spots where we get a lot of roof run-off. I use old Preen containers, that have handles, to carry the water - especially to newly planted trees and all of my big pots . . . even the ones indoors.
Just have to stay ahead of the mosquitos - but it works well.
I always thought that my well water, from my hoses, was a good watering source . . . but the rainwater beats it every time. I think it has magic properties that no other water has. (Please don’t burst my bubble! 
) 
For everyone wondering why special rates are charged for stormwater, consider that:
Stormwater systems that were designed to move water in all but the worst storms might now struggle with a fairly average storm, resulting in flooding. It costs money to upgrade or even just maintain these. Where it gets tricky is that the area that gets the impact (downhill) is not the full cause of the problem. Water can flow downhill from developments miles away, but these developments are high enough in the watershed that they don’t notice a problem. But when all those little “streams” from the developments’ runoff come together, it can be more like a raging river! Charging a fee based on impervious surface is a way of spreading that cost out more equitably. It’s also a way to incentivize minimizing your impervious surfaces. Believe me, cities and towns would rather not have to upgrade their storm drains, even if they had the money. It’s super intrusive, and trickier to design than you might think.
To think of it another way, imagine you have a neighbor that sprays herbicides upwind and kills your fruit trees. They don’t have any problems, it’s not their fruit trees! Who do you think should be responsible for the trees, you or your neighbor? Or should all parties pay an equal share to fix the problem? Do you apply for a grant from the feds to replace the fruit trees and install herbicide drift mitigation? Those are basically the options that local governments have to choose from when trying to tackle this issue.
Rainwater is going to be slightly acidic and relatively free from any additional minerals or pollution. Your well water may be more alkaline, or might have some sort of minerals in it that your plants don’t like (but might not be bad for you). If you are curious, there are labs that will test your water for a fee (we use G&C Coal Analysis Lab up in Pennsylvania for our mine water samples, but they do lots of other stuff too! They are fairly affordable as far as labs go).
That’s a great explanation Jay. We all live downstream, and whether we think about it or not, our actions most certainly will affect others. My Eagle Scout project involved mapping and stenciling all of the storm drains along the roads in my community. I think I had over 70 volunteers out in one day. Part of that was knocking on every door and sharing a pamphlet with what we were doing and why we were doing it (don’t dump your used oil down the garage floor drain, etc).
In communities seeing higher flooding rates than the “average” (looking at you Texas 1,000 year flooding), a large contributing factor for those events is likely the scale of hardscape and development which has occurred since those 1,000 year flood maps were drawn up, without an acceptable level of mitigation for the area of groundwater storage which has been removed by development.
One of my FAVORITE quotes from a professor in college is a simple one that I repeat in any situation that is appropriate, and this is one of those. DON’T BUILD IN A FLOODPLAIN. I also took that advice and bought a house on a hill instead of a valley, when I had the choice.
Hey i helped collect signatures for that and you can also put your sink your shower and dishwasher all on grey water now.
Also you are not limited to the size of rain container or cistern you store your water in just the number.
The gray water state initiative here was started by a bunch of solar companies and renewable energy leaders in boulder
Many of the older city’s in the East have a combined ,
storm water /sewer system.
So rain water adds to the sewage flow , making it a challenge to treat the combined flow , as one would want to do with sewage .
So any way to reduce the rainwater from getting in the sewer helps .
This may be one reason for rain taxes ? And rain barrel projects …
Cleveland Ohio has a 3 Billion dollar project going on to build massive tunnels just to contain the surge from heavy rains
In their “combined “ ( storm water / sewage ) system, so they can slowly treat the water before discharge into the lake .
So separating rainwater from sewage is important.
My house system , has separate sewer / gray water.
The only water that goes into the septic tank , leach field is from the toilet. Finding its way into some healthy oak trees.
Gray water from shower, sink goes to one end of the garden.
The greener end of the garden.
All of which comes off my roof , into cistern as my water source.
@Hillbillyhort — I have the same setup here… only our 3 toilets empty to my septic system… tank and field lines… showers sinks bathtubs… just goes down the hollow watering thousands of trees and bushes.
I do something similar with an old plastic garbage can. It has a lid which keeps the mosquitos out. I’ll use it to water sensitive plants and it’ll last all summer until it get refilled again in the late fall.