Rain Management 101 – The Stormwater Challenge

July 31, 2014
Jim Caldwell
Best Management Practices

This post was written by Jim Caldwell, the new Stormwater Manager with Howard County’s Office of Environmental Sustainability.  Welcome, Jim!

As a college undergraduate my major was wildlife biology.  I enjoyed studying the life histories of animals, the evolutionary changes that helped species adapt, and the ecologic principles that made it all possible.  Many of my classmates took a more practical approach studying wildlife management – the science of balancing human and wildlife ecology.   All these years later I still enjoy the wonders of wildlife biology, but the reality is that long ago environmental management became the foundation of my career.  The impact of human action on the natural environment led me on a quest to achieve reasonable balance with minimal conflict between man and the environment.  My latest challenge is stormwater.

Stormwater is as natural as rain itself.    Trees dampen the rate of fall giving the soil time to absorb the added moisture.  Open meadows slow the sheet flow of rain water allowing it to infiltrate the soil and recharge the water table.  Riparian buffers, defined by trees and brush along stream banks, protect the bank from erosion as the increased storm flows make their way downstream.  At times when the flow is too great for the stream channel to manage, stormwater spills out to the surrounding floodplain where water is either absorbed into the soil or stored until it finds its way back to the stream.  This is nature’s way of managing stormwater.

The human need for housing, roads, driveways, shops and parking lots has changed nature’s ability to absorb stormwater impacts and created the need for stormwater management – an engineering and science discipline dedicated to managing the tremendous flows created when rain runs over impervious surfaces.  Just imagine, a one inch rain event falling on a one acre parking lot generates more than 25,000 gallons of water – equivalent to emptying two backyard swimming pools!  To illustrate the long term impact of uncontrolled stormwater, consider that during the American Revolution, Elkridge, Maryland was a deep water shipping port.  Unfortunately, long ago the port filled with sediment carried to a large part by stormwater runoff from land clearing for both the growing community and agricultural fields.

Stormwater management is an evolving practice.  Early on, the intent was to get water off roads ASAP.   As such, there are many older communities with very little stormwater control, except for roadway storm drains leading directly to streams.  The result has been highly eroded streams, concrete channeled waterways, loss of aquatic habitat, and great amounts of downstream sedimentation.      Since the 1980’s, out of the concern for  Chesapeake Bay, stormwater management has matured and all new roadways and development designs include state-of-the-art stormwater management controls that address both  the quality and quantity of water reaching area streams.

Even though newer developments are designed to control stormwater, there are many older communities where stormwater still causes erosion, stream degradation and negative impacts on the Chesapeake Bay.  These locations are the current challenge for stormwater managers.  Implementing the methods and structures to control storm flows in these active, urban communities is like trying to repair a 747 in flight. The disruption can be both inconvenient and costly.  With land at a premium,  many of the newer control techniques are designed to mimic nature by creating methods to slow flow, increase infiltration and absorb nutrients in very small, localized settings.    More trees, rain gardens, green roofs and vegetated stream buffers are all part of the solution.   Also key to the solution is the involvement of more individuals constructing stormwater controls on their own property to help minimize impervious surface, improve infiltration and prevent stormwater from running off site carrying soil, fertilizer and trash to area streams.

The challenge of stormwater management is a challenge for everyone.  We all benefit from the built community, but we also depend on our streams and the bay for water supply, recreation,  a gift to future generations, and a place where aging wildlife biologists like me can still marvel at the diversity of nature.

Jim Caldwell

Stormwater Manager

Office of Environmental Sustainability