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What Is This Indicator, and Why Is It Important?
This indicator will describe the percentage of miles of stream
(stream-miles) in urban and suburban areas that are lined
with trees, shrubs, and other plants.
The amount of vegetation along a stream bank strongly affects
both water quality and the kinds of fish and other animals
that live in and along the stream. Plants lining a stream
bank shade the stream, making it cooler in summer, and they
serve as habitat for animals. Plants drop leaves and branches
into the stream, providing food and habitat for stream animals;
they also trap sediments and pollutants washing in from adjacent
areas, preventing them from reaching the water and helping
to maintain good water quality.
Why Can't This Indicator Be Reported at This Time?
Reporting on this indicator would require agreement
on a standard approach for defining and measuring streamside
vegetation, including the minimum width of plant cover for
a stream to be considered “vegetated,” and agreement
on whether and to what degree “unnatural” plant
cover such as lawns should be counted. Once such definitions
are established, data sources could be evaluated. These include
satellite-based measures, which currently cannot distinguish
very small landscape features, and locally generated information,
which can be quite detailed, although it may be incompatible
from location to location and very expensive to obtain.
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