Allen's and Mallett's Creeks


Note: This is archived info from the original website for the Friends of Dicken Woods. 
It was written when the Friends were in the process of saving DW

 

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:

  • "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,

  • "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.

  • 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.

  • 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.

  • 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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