Court decision leaves wetlands at a high risk
Aozotorp
guest commentary
Court decision leaves wetlands at a high risk
By Daniel Luecke
Feb. 18, 2001 - Colorado's waters include not just rivers, streams and lakes,
but ponds and wetlands that are spread around the landscape and that do not
necessarily flow directly into streams. Sometimes considered "isolated," these
wetlands and ponds are of enormous environmental importance, and for 25 years
they have been protected by the Clean Water Act like every other water body.
Yet their survival is now threatened by a narrow 5-4 decision of the U.S.
Supreme Court.
Exactly what the court decided is not fully clear. The case involved "isolated"
ponds outside Chicago that a local garbage agency wished to convert into a
landfill. Though used for breeding by large numbers of great blue herons, the
agency argued that their use by these birds did not justify their protection,
and the court agreed, suggesting that only wetlands and ponds that eventually
flow into navigable waters can be protected.
We think the court's decision was scientifically unsound. In fact, isolated
waters perform precisely the same water quality, flood protection and other
hydrologic and biological functions as protected waters. So-called isolated
ponds and wetlands (often isolated only as a matter of degree) provide a basic
function that wetlands adjacent to navigable waters and their tributaries
provide.
Only 5 percent of the area in the Rocky Mountain states is occupied by rivers,
lakes, ponds and wetlands, but more than 65 percent of the region's species
rely, for at least some portion of their life cycle, on this limited habitat
resource. While it is true that only a tiny fraction of the 5 percent may be
"isolated" wetlands and ponds, their very scarcity makes them important.
The term "isolated" wetland or pond is not a precise, scientific concept. In
general, the term is used loosely to define wetlands or ponds that lack a
surface outlet to downstream rivers and bays. Such wetlands and ponds typically
form in depressions in the landscape and are "isolated" because the higher
elevation of the land around them traps surface runoff, but rarely groundwater
flows.
The basic function served by "isolated" ponds and wetlands is simply that they
store water at least temporarily, often filter it through their plants and
soils and keep it from flowing farther downhill and downstream over the
surface.
This prolonged storage of water in many isolated wetlands affects water quality
by holding water back during wet seasons and feeding the water slowly to
streams and rivers through groundwater during the drier months of the year.
This water is called "base flow," and it is what keeps streams from drying up
during drier months. Drainage of any wetlands that recharge groundwater,
whether isolated or not, can decrease this base flow to streams.
Isolated wetlands and ponds also provide some of this country's important
migratory habitats for waterfowl and many other species of water birds.
Although most of these basins have been drained, some remain.
The Rainwater Basin in Nebraska, for example, still consists of thousands of
"isolated" wetland ponds in an area south of the Platte River. Although they
may be inundated only through the early spring migration period, between 2
million and 3 million migratory waterfowl and a huge variety of shorebirds and
wading birds use them, often for several weeks, as a rest and refueling stop on
their northward migration precisely during this period.
Some species are particularly dependent on these ponds, including 90 percent of
the entire population of white-fronted geese and 50 percent of the mallards
that use the mid-continental flyway.
While less visible than waterfowl and wading birds, amphibians and reptiles -
including frogs, salamanders, snakes and turtles - also play an important role
in ecosystems. They comprise an important part of the food chain, eating
insects and plants and, in turn, being eaten by fish and waterfowl. Amphibians
as a whole rely heavily on isolated, often seasonal, wetland ponds for breeding
or feeding sites. Many species prefer isolated ponds precisely because they
harbor fewer predators such as fish that eat amphibian eggs and larvae.
In addition to their value as breeding sites, isolated ponds also provide
critical "ecological connectivity" for many amphibians. Changing conditions in
water bodies can cause local species to become extinct, so the long-term
presence of amphibians depends on the ability of other amphibians to recolonize
sites after extinction. Small isolated wetlands may provide a sufficient
density of aquatic habitat in some areas to allow amphibians to migrate and
recolonize lost sites.
All of these conditions highlight a simple fact: isolated water bodies are
critical to the overall biological integrity of this region's and the nation's
waters. They are now at risk. It is critical to find new ways to protect them.
Daniel Luecke is regional director for the Rocky Mountain office of
Environmental Defense.