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The Issues
Allen's Creek and Mallett's Creek
Below the streets of Ann Arbor are two sewer systems, one for
sanitary sewage and one for storm water runoff. The latter system is
known by the U.S. Environmental Protection Agency as a municipal
separate storm sewer system (MS4). These sewer pipes take storm water
runoff from our impervious surfaces (roads, sidewalks, parking lots,
roofs) and transport it directly to the Huron River, completely
untreated. In the case of the Dicken neighborhood, the MS4 makes use of
both Allen's Creek, heading north, and Mallet's Creek, heading south,
to direct the runoff to the Huron River. That is, the underground sewer
pipes from the Dicken neighborhood empty directly into these two creek
systems,
where the runoff continues flowing until it reaches the Huron.
All three water bodies - the Huron River, Allen's Creek, and
Mallett's Creek - have suffered significant pollution problems due to
the continuous development and sprawl that has consumed former open
lands in the Huron River watershed. Where formerly open land used to
absorb storm water, the newly paved surfaces now shed that water to the
River. Dicken Woods is one of the last remaining natural areas on Ann
Arbor's west side that still functions to absorb storm water rather than
simply sending it to the River.
How does development, miles away from the River, affect the river's
water quality? According to the Environmental Protection Agency:
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"Storm water discharges from MS4s in urbanized areas are a concern
because of the high concentration of pollutants found in these
discharges. Concentrated development in urbanized areas substantially
increases impervious surfaces, such as city streets, driveways, parking
lots, and sidewalks, on which pollutants from concentrated human
activities settle and remain until a storm event washes them into nearby
storm drains. Common pollutants include pesticides, fertilizers, oils,
salt, litter and other debris, and sediment. Storm water runoff picks up
and transports these and other harmful pollutants then discharges them –
untreated – to waterways via storm sewer systems. When left
uncontrolled, these discharges can result in fish kills, the destruction
of spawning and wildlife habitats, a loss in aesthetic value, and
contamination of drinking water supplies and recreational waterways that
can threaten public
health." [Storm Water Phase II Final Rule: Overview, p.1]
Allen's Creek
The Ann Arbor Planning Department Staff Report notes that Dicken
Woods is within the headwaters of Allen's Creek, an important tributary
of the Huron River. Allen's Creek is a controversial Ann Arbor
environmental entity, with significant impact on development of downtown
Ann Arbor, due to concerns about floodplain issues, as well as
significant impact on the quality of the Huron River. Allen's Creek has
recently been subject of an intense research and planning process,
resulting in the May 2001 Michigan Department of Environmental
Quality-approved "Allen's Creek Watershed Management Plan,"
designed to restore the health of this important waterway. Below are
just a few excerpts from that plan, but even a casual reading of that
plan shows the enormous impact of Allen's creek on many fronts, from
flooding in many areas of the city in parks, streets, basements &
businesses, to the quality of our drinking water, to soil erosion,
killing of downstream trees, and so on. According to that plan,
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"Allen's Creek is a tributary of the Huron River that courses through,
and is contained within, the City of Ann Arbor. Surface water flowing
through the Ann Arbor urban environment accumulates and concentrates
pollutants that then flow into the Huron River. The Huron River serves
as a drinking water source, recreation resource, and aquatic habitat in
Southeast Michigan. Moreover, this watercourse empties into Lake Erie,
the shallowest of the Great Lakes.
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Water runoff is a significant public health and economic concern in Ann
Arbor. Poorly managed surface water runoff damages property, degrades
ecosystems, and introduces risks for injury from erosion and
contamination. Repetitive occurrences of surface and basement flooding,
sometimes mixed with sewage, are clear symptoms of a stormwater
management system stressed beyond its capacity. Moreover, the high
level of impervious surfaces in our urban landscape reduces groundwater
recharge as well as contributing to the degradation of water quality and
risk of flooding. Poorly managed surface water runoff and decreased
surface water quality threaten property values and tax revenues, with
the potential to erode the economic vitality of the community and
thereby contribute to urban decay.
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Most of Allen's Creek is enclosed and inaccessible -- out of sight and
out of mind except when storm events make it a public nuisance or
hazard. Many residents are likely unaware of its existence. With most
of the watercourse enclosed, Allen's Creek is often thought of as an
“urban drain” for stormwater conveyance.
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Although Allen's Creek has the potential to be a community amenity,
issues of water quality, flooding, ecological health and structural
integrity overshadow the creek's potential. With proper planning,
government oversight, educational efforts and community investment,
Allen's Creek will again become a resource to the city. By improving the
health of the Allen's Creek Watershed now, the city is likely to reap
long-term savings.
That report's section on "Natural Features" goes on to say:
- "Short stretches of the few remaining open channels and many of the
enclosed sections of Allen’s Creek transverse areas with desirable
natural features such as woodlands and ravines. The few sections
remaining above ground routinely attract walkers, children and wildlife,
and many of the enclosed sections underlie neighborhood parks and
greenspaces. The natural features of these areas need protection.
Moreover, with community involvement and investment, Allen's Creek could
provide the residents of the city with much more than stormwater
conveyance through the addition of natural areas of greenery, flowing
water, and repose. With this, also, would come the commensurate
economic benefit to the community."
And regarding safety issues, the report states:
- "Development has added impervious surfaces, such as rooftops,
driveways, roads and sidewalks. Eventually, increased levels of
imperviousness contributed to major flooding (in 1947 and 1968), as well
as to recurrent localized flooding experienced in recent years during
moderate or large rainstorms (e.g., in 1998 and 2000). Increased runoff
velocities eroded banks of open stream channels, which led to further
enclosure projects, such as the Liberty-Glendale project in 1997-98."
Finally, the plan's recommendations section says:
- "Opportunities exist to create a greenway system through the Allen's
Creekshed. Residents and community members within the Allen's Creek
watershed may be receptive to the use of parklands within Ann Arbor for
stormwater detention purposes if the process also enhances the
recreation amenity of the parks. This greenway should be integrated
into other city plans. For example, an Allen's Creek greenway could
start from the planned greenway along the Huron River and run through
downtown Ann Arbor all the way up to the University of Michigan athletic
campus. Furthermore, the greenway could potentially branch out
along Allen's Creek up through Ann Arbor's west side, linking existing
parks (and perhaps creating new park spaces) along the creek system."
Mallett's Creek
Dicken Woods also drains partially to Mallett's Creek, the main
waterway from south Ann Arbor to the Huron River. Like Allen's Creek,
Mallett's Creek is a severely stressed urban creek and drainage system,
and has recently been the subject of a massive public/private
partnership planning effort to begin restoring the creek to it's full
potential, resulting in the Mallett's Creek Management Plan.
Again, even a casual reading of that plan argues for taking great care in further development within the creekshed:
- "As a result of expansion of urban development in Mallett's
creekshed, Mallett's Creek has become dangerously degraded, producing a
great deal of surging of the creek and consequent flooding of
properties, reduction of biological live in the creek, and unacceptably
high levels of pollutants which flow into and degrade the Huron River."
Prominently listed in it's executive summary, The Mallett's Creek
Management Plan requests the City of Ann Arbor Parks & Recreation
Department to:
- "Expand the goals of the Parks, Recreation and Open Spaces Plan [the
parkland/open space acquisition millage] to include creek protection
through creation of more non-turf area, increasing groundwater
retention/detention facilities in public parks, reduction of impervious
surfaces, expanded use of native species, maintenance of creek buffer
areas ...." [p. 1]
While the "Proposed Action Plan" section expands on this request:
Park Management and Policy.
- "Ann Arbor parks can play a major role in protecting and improving
the functionality of Mallett's Creek. We therefore propose a number of
changes in park management policy:"
"Expand the Parks goals by including parks as functional
resources, in addition to visual resources. Functional uses include
water retnetion and cleansing, air purification and cooling, wild plant
reserves and wildlife habitat, in addition to their roles as resources
for physical activity and mental recharge for people. Improving this
aspect of the Parks, Recreation and Open Spaces system can involve
purchases of high quality natural areas, expansion of the Natural Area
Preservation program, and the creation of more non-turf areas in
existing parks ...."
"Expand the Parks goal of protecting and improving the Huron River by
including protection of its tributaries and the watershed land. Only by
looking at the watershed more holistically can we hope to improve water
quality." [p. 12]
And it is also worth noting that when it adopted (on June 1, 1999)
the "Mallett's Creek Watershed Resolution," the Ann Arbor Planning
Commission stated:
- "Resolved, the Ann Arbor City Planning Commission hereby
supports the goals of the Malletts Creek restoration planning effort and
encourages residents and property owners of land within the watershed
to participate in the planning effort."
By saving this natural area that sits at the highest elevation in the
city, the Friends of Dicken Woods can play an important role in the
helping to improve the water quality of Allen's Creek, Mallett's Creek,
and through them, the Huron River.
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