Stormwater – here’s the rundown on runoff…

One of the hottest topics of public discussion when it comes to the proposed plan for cleaning up Butte’s urban Superfund site is the waiver for copper and zinc levels during storms. I’ve already covered this waiver in a couple of my previous columns, so I won’t go into great detail again. But the long story short is that instead of our creeks being required to meet state water quality standards for both dissolved and particulate substances (in this case, copper and zinc), they are required to meet the federal standards, which only apply to the dissolved fraction. Both standards are protective of humans and the environment.


This is probably the most important thing to understand: Our streams in Butte will be held to the same standard of water quality that applies to roughly 75 percent of the states in our country (37 states or 74 percent, to be exact). But there are a few other things we should all understand.


First, these numeric standards for copper and zinc only apply during storm events, when water is running down our streets and into the creek after rain or snowmelt. The rest of the time, when our streams are flowing normally, they are required to meet the same water quality standards as any other stream in Montana.


Secondly, it’s important to point out that no other city in Montana – or any state for that matter – is required to meet numeric water quality standards during storm events. Why? Generally, because it’s “technically impracticable,” to steal a Superfund term.  What this term means is that it’s not possible and/or practical to meet a specific standard using the technology available. And when it comes to municipal stormwater, this isn’t a “waiver” – it’s the law of our land.


Let’s take a closer look at municipal stormwater and how it is regulated…


Municipal stormwater is the water that occurs when it rains in our cities and towns and the rainfall runs off our roofs, yards, sidewalks and streets and into our storm sewer drains and local water ways (creeks, lakes, rivers, wetlands). The amount of water that runs off an urban area is about FIVE TIMES the amount that runs off a natural, undeveloped area of the same size. This is because we replace porous, natural surfaces like forests, grasses and other soft, native grounds with hard, impervious structures with surfaces like metal, asphalt and concrete that do not allow water to soak in. The result is a lot more water moving downstream a lot faster than it would naturally. These greater, faster quantities of water can erode natural grounds and also carry with it everything on our city’s surfaces. And by everything, I mean EVERYTHING.


·       Dirt, sand and other sediments, which in cities mean things like small pieces of asphalt, concrete and paint.

·       Vehicle wastes, such as oil, grease, and other toxic chemicals and substances, like antifreeze or metal from brake linings that continually come off our cars, trucks, motorcycles and bicycles.

·       In cold climates like Montana, our state and cities apply sand and chemical deicers to keep vehicles safely on the road. All of these wash into our waters when the snow and ice melts or the rains come.

·       Fertilizers, herbicides and pesticides used on our parks and lawns and the clippings that find their way to the drain and streams.

·       Bacteria and viruses from pet wastes and other animals.

·       Litter and trash – including plastics, papers and nasty things like cigarette butts and household batteries.


All of these things are in most cities’ municipal stormwater runoff. And all cities’ stormwater eventually runs into our streams, rivers, lakes, wetlands and oceans. Here’s a fact that might surprise you: Stormwater pollution is the number one type of water pollution in America.


How do we regulate it?    


The federal Clean Water Act regulates municipal stormwater in two ways: Phase 1 regulates all of the larger cities in America, those with populations of 100,000 or greater. Phase 2, which have only been in place here in Montana since around 2000, regulates smaller cities, those with populations of 10,000 or larger. There are roughly 750 Phase I and 6,700 Phase II regulated communities in the U.S. You may have also heard the term “MS4” when regulators talk about stormwater. This is just an acronym for “Municipal Separate Storm Sewer System,” which is the system of drains, pipes, ditches and other management features that make up a city’s stormwater system.  


Both of these phases require cities to develop management plans to reduce the contamination that comes from their urban stormwater, or MS4. While the goal of these stormwater regulations is to keep our local streams and waters clean, there is no requirement for cities to be in compliance with numeric standards. Why?


Again, there is no practical way to technically control or treat all of the variable types and quantities of contamination that are in municipal stormwater because it comes from everywhere, or at the same time, nowhere in particular. (Note: they call this type of pollution “non-point source pollution.”) Because of this impracticability, the MS4 regulations for cities require best management practices laid out in a plan to basically, do the best we can.  So, in that regard, Butte has stormwater standards that are actually stricter than most cities.


In fact, because it’s not required (compliance with numeric standards), it’s very difficult to find comparable numbers of how other cities’ stormwater compares to our own. In a recent presentation by retired DEQ Superfund manager Joe Griffin, he displayed the only data he was able to find for another city in Montana – Big Fork, population ~4,500. What those numbers show is that today, Butte and Big Fork have about the same amount of copper in its urban stormwater runoff. Keep in mind that Big Fork is not under the same numeric standards Butte is for Superfund. Big Fork isn’t even required to comply with MS4 regulations, because it’s less than 10,000 people. So, while Big Fork isn’t a mining city with Superfund status, it appears that the amount of copper that comes from its 4,500 residents is the about the same as what we have here in Butte. Perhaps the biggest difference of significance is that in Butte, we have a small stream that has to handle all of our urban runoff; in Big Fork, there is the Swan River and Flathead Lake.  


In Butte, we will have numeric standards to help keep our creeks clean from the impacts of our historic mining and smelting past.  But it’s up to all of us to keep our water clean. Public education is widely accepted as the best tool to reduce the pollution that comes from urban stormwater runoff. We all contribute to the problem, so we can all do something to change our behaviors in order to improve our water quality. I hope this column leaves you more educated and capable of understanding stormwater and how it relates to keeping Butte’s creeks clean. I also hope you understand that while our Superfund cleanup will improve our area’s water quality, it’s up to all of us to keep it that way.


Questions? Comments? Send an email to  I’ll send you a reply, or do my best to address your ideas in a future installment of Restoring Butte.

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