Back to StoriesSqueezing the Waterways in Greater Yellowstone
Once the creek leaves the refuge it quickly transitions to the urban environment at the north end of Jackson. The following photos show how gradual urbanization has grown.
By maintaining healthy streams and riparian areas in urban settings, a two-fold goal can be achieved. We can maintain connectivity and habitat for wildlife, which is a rather big deal for our local mule deer herd that must navigate five-lane roadways and a gauntlet of structures and fences to move from the hillsides where they browse to the creek for a drink and for winter shelter. And we can make our town a more pleasant place for people.
June 12, 2024
Squeezing the Waterways in Greater YellowstoneAs Jackson Hole swells with development, MoJo columnist Susan Marsh writes that waterways like Flat Creek need our attention
The town of Jackson, Wyoming. Agricultural land adjacent to Jackson is slated to become the next large residential subdivision. A proposed mega-hotel with two levels of underground parking, to be located on the north end of town near the historic confluence of Flat Creek and its major tributary Cache Creek, is being considered by the town council. Photo by Nick Sulzer / Buckrail.com
by Susan
Marsh
While the
Teton Pass landslide continues to make national news, a consortium of expert
engineers is hard at work figuring out a way to reopen it this summer. Discussions
continue over a longer-term solution; meanwhile, the event is a reminder that
we can’t take anything for granted. So I leave the experts to their work while
focusing on another issue—one that also asks for a long-term solution.
The current
urban sprawl in our region is reshaping a number of the rivers and creeks that
happen to be in the way, increasing the level of pollutants, nutrients, and
sediment entering the water. Creek channels and profiles are being altered by
structures and flood control. Native flora and fauna are being replaced by
exotics and the water’s temperature is rising, among other changes, all of
which worry me.
While
acknowledging the past and ongoing efforts to improve streams, I think most
towns in the region have a poster child for the neglect of an urban waterway. In
Jackson, the stream that graces our poster is Flat Creek.
Flat Creek rises
in the Gros Ventre Wilderness, from which it flows in near-pristine condition. But it doesn’t flow far before the insults begin.
Lack of
protection for streamside vegetation has degraded the creek within the National
Elk Refuge, where a few thousand elk spend the winter months. Their numbers
have eliminated sapling cottonwoods and shrubs along Flat Creek, except for one
stretch that has been protected by a fenced exclosure. The fenced-off area,
vibrant with diverse deciduous shrubs and young cottonwoods, gives an
indication of what Flat Creek would look like if the rest of it were similarly
protected.
Once the creek leaves the refuge it quickly transitions to the urban environment at the north end of Jackson. The following photos show how gradual urbanization has grown.
Streets and buildings
have been built directly adjacent to the creek, and significant investment has
been made by the Flat Creek Watershed
Improvement District and Teton Conservation District in an effort to prevent
flooding due to ice dams in winter. But we’re trying to fix a problem that we
have created instead of allowing the creek and its associated groundwater to
flow naturally.
Why does this
matter? For starters, we would prefer to avoid having this infrastructure,
including homes and businesses, flooded. More importantly, if we don’t take
steps to improve the creek’s ability to flow more naturally, the existing
problems will only get worse.
In
undeveloped areas, water moves into drainages systems after being slowed and
absorbed by soil and vegetation. Where natural sponges in the form of soil,
riparian areas, and forests are replaced by impermeable surfaces—concrete,
asphalt, roofs—water can’t filter into the ground. Runoff happens more quickly,
increasing the chance of the creek overflowing its banks.
When the
natural stream channel is made artificially narrow by encroaching structures,
riprap or fill, seasonal high water and stormwater runoff have nowhere to
spread out, so water rises in the channel and backs up to inundate the area
upstream.
Removing
trees, shrubs and grasses from undeveloped property, along with subsequent excavation
and grading, will leave the land unprotected from erosion. Weeds get a
foothold. Sediment from the bare area ends up in the creek and large amounts
enter Flat Creek at manmade outfalls. The town of Jackson is working to correct
this problem, but these are in violation of EPA standards.
Replacement
of said undeveloped land with development equates to a loss of habitat for
aquatic species and the adjacent riparian areas needed by wildlife—including
mammals and birds. Also lost is the parklike atmosphere of natural streams that
attract people for rest and recreation. Water temperature rises as shade-providing
streamside vegetation is replaced by concrete, which warms the water flowing
over it.
Water quality
becomes impaired from urban runoff, which is laden with sediment and typically contains
fertilizers, hazardous chemicals, heavy metals and hydrocarbons from vehicles, as
well as all manner of other substances that don’t belong in the creek.
Where
channels have been straightened or narrowed and vegetation has been removed
from the banks, streamflow velocities increase. Result: increased channel and
bank erosion.
Jackson town
managers and engineers are well aware of these problems. But as with all
desirable mountain towns, commercial square footage is at a premium here, and
newer developments are designed to maximize that potential. Moderately sized
buildings that leave some open space on lots for trees, grass and shrubs are
being replaced by structures that take up the entire property with concrete walkways
extending from structure to curb, leaving no room for vegetation on which the
eye can rest or rain can find its way into the ground.
Residential
parts of town are being redeveloped in a similar way. Within a couple of blocks
of my house are a dozen “For Sale”
signs in front of houses once owned by neighbors I knew. Most of these houses
will be torn down and the mature trees removed, to be replaced by structures
twice their size. Driveways and garages tend to be wider as well, with a
corresponding reduction of vegetation.
The one part
of town that remains relatively natural is around Karns Meadow Park, where the
creek meanders through a dense and diverse assemblage of willows, river birch
and other tall shrubs. It is a jewel in the midst of development.
While local government entities and nonprofits, including Trout Unlimited
and Protect Our Waters Jackson Hole, have tried to improve conditions in and
around Flat Creek, the march of construction and development continues apace,
with more in the works.
Adjacent to town, agricultural land is slated to become the next large
residential subdivision. A proposed mega-hotel with two levels of underground
parking, to be located on the north end of town near the historic confluence of Flat Creek and its major tributary Cache
Creek, is being considered by the town council. If approved as submitted, this
structure will require pumping groundwater from around the basement structure
to prevent hydraulic buildup against its walls. It’s not hard to imagine where
the pumped water, with its potential load of fine sediments, will end up.
I wonder when
we are going to seriously address the health of Flat Creek, which could be the
thriving heart of Jackson, rather than continuing to degrade it. Other towns in
our region are resurrecting their urban waterways, but I’m not sure that is a
priority here. It’s more a matter of trying to keep an imprisoned creek from
causing damage to all that we have built around it. We should learn from other
urban areas that have created more risk of flooding and damage as they add to
the infrastructure.
By maintaining healthy streams and riparian areas in urban settings, a two-fold goal can be achieved. We can maintain connectivity and habitat for wildlife, which is a rather big deal for our local mule deer herd that must navigate five-lane roadways and a gauntlet of structures and fences to move from the hillsides where they browse to the creek for a drink and for winter shelter. And we can make our town a more pleasant place for people.
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