Stormwater

When water from rain and melting snow runs off roofs and roads into our rivers, it picks up toxic chemicals, dirt, trash and disease-carrying organisms.

Scientific studies show that stormwater pollution rivals sewage plants and large factories as a source of damaging pollutants in our drinking water!

We Support Innovative strategies capturing, controlling and reusing rainwater

Rainwater capture and control practices, also called green infrastructure, help address stormwater problems by restoring parts of the natural water cycle that were paved over by development. Strategies most commonly being used in urban areas include green roofs, rain barrels and cisterns, rain gardens, pocket wetlands, and permeable pavement. Not only do these smarter water practices help address stormwater runoff, but they also beautify neighborhoods, cleanse the air, reduce heat-related illnesses, save on energy costs, boost economies, and support American jobs.

Why does stormwater management matter in Montana?

Stormwater runoff is one of the fastest growing sources of pollution in Montana.  As our Big Sky state grows in population, so too do our impacts on the local environment.  Stormwater runoff can cause a number of environmental problems:

  • Fast-moving stormwater runoff can erode stream banks, damaging hundreds of miles of aquatic habitat.
  • Stormwater runoff can push excess nutrients from fertilizers, pet waste and other sources into rivers and streams. Nutrients can fuel the growth of algae blooms that create low-oxygen “dead zones” that suffocate aquatic life.
  • Stormwater runoff can push excess sediment into rivers and streams. Sediment can block sunlight from reaching plants, artificially raise local water temperatures to unhealthy levels for fisheries, and suffocate macroinvertebrate life, which is critical food for trout and fish populations!
  • Stormwater runoff can push pesticides, leaking fuel or motor oil and other chemical contaminants into rivers and streams. Chemical contaminants can harm the health of humans and wildlife.
  • Stormwater runoff can also lead to flooding in urban and suburban areas.  Runoff season for the past few years in Montana has resulted in a rising number of flood issues based on poor land development policies at local and county government levels.

We need to slow the flow!

Forests, wetlands and other vegetated areas can trap water and pollutants, slowing the flow of stormwater runoff.  But when urban and suburban development increases, builders often remove these natural buffers to make way for the impervious surfaces that encourage stormwater to flow freely into local waterways.  This exact scenario of wetlands fragmentation is presently occurring throughout Southwest and West-Central Montana’s populated river valleys!

What are impervious surfaces and why are they a problem?

Impervious surfaces are paved or hardened surfaces that do not allow water to pass through. Roads, rooftops, sidewalks, pools, patios and parking lots are all impervious surfaces.  Impervious surfaces can cause a number of environmental problems:

  • Impervious surfaces can increase the amount and speed of stormwater runoff, which can alter natural stream flow and pollute aquatic habitats.
  • Impervious surfaces limit the amount of precipitation that is able to soak into the soil and replenish groundwater supplies, which are an important source of drinking water in some communities.
  • Impervious surfaces that replace soil and plants remove the environment’s natural ability to absorb and break down airborne pollutants.

According to the U.S. Environmental Protection Agency (EPA) the presence of roads, rooftops and other impervious surfaces in urban areas means a typical city block generates more than five times more runoff than a forested area of the same size.  This type of local, disproportionate environmental impact is especially important to address in Southwest and West-Central Montana where our groundwater and surface water are hydrologically linked, and thus stormwater can directly affect the health of our local waterways!

Impervious surface data are used to measure the rate of development across the watershed and to identify high-growth areas and patterns of sprawling development.  Between 1990 and 2007, impervious surfaces associated with growth in single-family homes are estimated to have increased about 34 percent, while the watershed’s population increased by 18 percent.  This indicates that our personal footprint on the landscape is growing.