Where the Rain Goes

Rain garden in St. Stephen’s Lake Park in Columbia, MO (Photo courtesy of Steve Johnson, Executive Director of the Missouri River Communities Network)

Don’t it always seem to go that you don’t know what you’ve got ‘til it’s gone?  They paved paradise, and put up a parking lot!

Joni Mitchell warned us years ago about what we’re doing in the name of “progress.”  As we moved from the city to the suburbs to the exurbs, we’ve been slowly paving over our metropolitan areas at an alarming rate.  Of course, with paving comes piping – channeling the rainwater that can’t penetrate into the ground into concrete pipes that quickly carry it to our creeks, streams and rivers.

This is growing into a significant problem.  During heavy storms, huge volumes of water are channeled into creeks, carrying residues from cars, lawn-care products, salts and other pollutants directly into our streams, and in the process eroding the banks of the natural waterways.  Ultimately, this increases flooding because the stormwater doesn’t get a chance to seep into the ground.  In a natural system, much of the water in creeks and streams comes from groundwater, which is filtered and purified by the earth itself.  Our groundwater tables are at all-time lows these days, from a combination of pumping for crop irrigation and a lack of replenishment.

The St. Louis Metropolitan Sewer District, which has the responsibility to manage both sewer and stormwater systems, recently began charging property owners a special surcharge based on the total impervious surface area of the property, which includes rooftops, driveways, patios and parking lots.  This was intended to be a more sensible means by which to apportion the charge, which used to be a flat rate per property.  While this helps MSD fund stormwater maintenance projects, it’s not currently a significant enough cost to incent property owners to make changes. 

There are a number of things you can do to reduce the flow of water into the stormwater drains.  The two more expensive options – adding a “green” roof or a permeable paved driveway – will get you a reduction in the impervious surface area charge, which is destined to become a more significant portion of your sewer bill.  However, the two less expensive strategies – adding rain barrels and rain gardens – will help solve the problem but don’t currently have any incentives.  Hopefully at some point MSD will find a way to develop a metric off of which to base a financial incentive for these implementations.

A rain barrel is the cheapest and simplest option.  These barrels come in a variety of colors, shapes and sizes.  They usually hold about 60 gallons, but larger models that hold 300 gallons or more are also available.   There are square containers with a cutout so that it fit into the corner of a building, stone-shaped containers and plastic tanks that are designed to be buried underground.  But a standard 55 gallon barrel kit is the most common, and can be purchased and easily installed for under $100.

In addition to reducing your runoff, a great benefit of having a rain barrel is that you can water your plants with fresh rainwater.  In the summer, when water demand is highest, you can draw from your own reservoir.  The ideal setup includes an automatic release, which slowly drains a gallon or so an hour into a nearby flower bed.  That’s also a great way to minimize the maintenance of having to manually empty the barrel before the next rainfall.

Another option is the rain garden.  These can occur naturally, as in a low-lying “bowl” in a yard or field, but can be manually constructed on a gentle slope using a berm.  Native water-loving plants can line and fill the basin, which is designed to hold the water for a couple days.  (Because the water is only held for a short time, rain gardens are not a habitat for mosquitoes.  In fact, rain gardens attract beneficial insects that actually keep mosquito populations in check.)  Rocky or sandy soils allow the water to infiltrate the ground more quickly than soils with a high clay content, so the design of the rain garden has to take soil composition into account.  These gardens can be a beautiful addition to your landscape, and can serve a valuable purpose in slowing the flow of water into storm drains, and replenishing our valuable groundwater.  For more information on rain gardens, check out ShowMeRainGardens.com.

There are no easy solutions to our water problems, but if we all do our part at the beginning of the process, the downstream impact will be much more manageable. 

This was published in the Going Green section of the April 2010 issue of Spirit Seeker magazine.