Effects of Urban Development on Streams & Aquatic Life (4)


I work for the Center for Watershed Protection
located in the suburbs of Baltimore City. The Center is a national non-profit watershed
and stormwater management think-tank Prior to
working for the Center, I
spent 30 years working for Baltimore City,
one of 28 sites that participated in the Nationwide Urban Runoff Project which was the first comprehensive
assessment of the causes and effects of urban stormwater runoff through � which concluded
that urban runoff was as bad as secondary treated sewage and led to the Stormwater Management
Permit Program of the 1990s. We have few success stories on mitigating
the effects of urbanization. Most of the development in this country has occurred prior to stormwater
management regulations. The Biological Conditions Gradient is a useful
tool to help predict the effects of different management options.
The �piping� of streams was a common practice to control the increases in urban runoff associated
with impervious cover and to control disease which at the turn of the century was believed
by many to be carried by miasma ( disease spread by vapors from rotting vegetation and
human waste). Prior to coming to work for the Center, I
was the Chief of Baltimore City�s Surface Water Programs for over 20 years.
One of the main impacts of
impervious cover is the need to convey the additional runoff.
For over a century, Baltimore City�s solution to managing stormwater runoff was to bury
streams beneath the streets. The maps above show the reduction in stream density and the
replacement of first and second order streams with storm drains as indicated by red lines
in the map to the right. Many of the sewers were constructed over 70
years ago in leaky terra cotta pipes with the major trunk lines constructed under the
stream beds. Al though not shown, the water distribution system is equally complex and
leaky. The figure to the right shows how these pipes
are placed under a typical street. The impacts to the stream ecosystem are not
just related to stormwater. Water and wastewater infrastructure is typically placed in the
stream channels. All three pipe infrastructure systems crisscross throughout the watershed.
The
water quality of the stream is largely impacted by infrastructure failure. All 3 water systems
are regulated and managed by different entities. The three
need to work together as one to meet our water quality goals.
After decades of working with the communities throughout the City it became obvious that
the goal of restoring the human ecosystem and making it more sustainable has to integrated
into the restoration of the aquatic ecosystem. Practices that benefit both should be emphasized.
Examples of urban restoration. Turning vacant lots into a stormwater management asset. 14,000
vacant lots currently exists. Bioretention provides �green space� to
an ultra urban community. Replacing impervious cover with landscaping
is one of
the best things we can do. At last count, over 30 school yards were greened.
There is a �grass roots� effort in Baltimore City to �Green Communities� because of the
cumulative benefits. While the price tag for restoring our waterways
is expensive, we are beginning to identify synergies among regulatory programs (3-pipes)
Restoring our waterways can help to restore our communities. This should factor into the
cost

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