Given the economic
impact of commercial navigation, is it reasonable to consider reversing
all hydrologic modifications? What responsibility does commercial
navigation have to preserving water quality?
Many made to rivers in order to support commercial
navigation have affected the functions of natural river systems.
Dams were constructed to even out the seasonal changes in water
flows, creating vast lakes behind them. Curves and meanders removed
to straighten rivers have cut wetland areas off from nourishing
river waters. Channels and wing dams, constructed to accommodate
barges and boats have narrowed riverbeds and increased the speed
of the waters flow.
of the rivers water, died off, eliminating important habitat.
Wetlands have traditionally served not only as habitat, but also
as living sponges, soaking up excess water. They are also natural
filters, preventing pollutants from dumping directly into waterways.
Areas flooded with river water suddenly become lakes. These lakes
bury farmland underwater and change the types and number of animals
in the area. Now many communities around these artificial lakes
rely on the water for their livelihood as they cater to boaters,
anglers (fishermen and women), and other water recreationists.
All these changes were made to make navigation faster and less dangerous.
Commercial navigation is a multi-billion dollar business, providing
national and international distribution of goods and services. Does
it make sense to reverse the changes that were made? Is it even
possible to reverse? Can water quality and navigation co-exist?
The commercial activity on working rivers can also pose a threat
to water quality.
- The cargo
hauled by boats and barges ranges from rubber tires to toxic chemicals.
Accidents can spill dangerous chemicals or petroleum products
into water, seriously impairing water quality.
- The volume
of traffic on a working river can also threaten its water quality.
The more boats and barges moving up and down, the greater the
risk of a spill or accident. Theres also more potential
from pollution and dirt the vessels carry with them.
- The increased
traffic also increases the rate of erosion, contributing sediment
to the waterways.