Project Details

How do natural areas help the river?

Natural areas provide habitat for many animals and plants, like this leopard frog

Natural areas provide habitat for many animals and plants, like this leopard frog

The Huron is the cleanest urban river in Michigan. This is mostly due to the substantial natural areas that remain throughout the watershed – about 44% of it is still forest, wetland, and fields.

Forests, prairies, wetlands and other natural areas are beautiful and important places on their own.  They also play a critical role in keeping the Huron River clean.

  • Natural areas store and absorb rainwater and melting snow. Plants soak up and filter this water before it flows into the river.
  • Rain and snow in natural areas also soaks into the groundwater, where it eventually flows back into the river in the form of springs and seeps. Along the way, that water gets filtered by the soil and cools, so it is healthier for river animals. And the steady flow of spring-water keeps the river flowing even when there’s not much rain.
  • Wetlands and low-lying natural areas absorb excess water, preventing flooding downstream.
  • Natural areas provide homes for trees and plants, habitat for wildlife, and of course offer people places to relax, play, and enjoy nature.

But natural areas are disappearing—paved over for shopping malls and subdivisions. One of the biggest threats to the Huron River is the loss of natural areas.

Map of Natural Areas in the the Huron River Watershed

 In order to provide local communities, land conservancies, and other interested organizations with information about the location and value of our remaining natural areas, HRWC has completed a “Bioreserve Map” that ranks the areas based on the ecological services they provide.  HRWC used aerial photographs taken over Oakland, Livingston, Wayne, Washtenaw, and Monroe counties to create the map. We drew boundaries around areas on the photographs that appeared to be woodland, wetland, or open field and mapped nearly 1,700 sites, for a total of 237,000 acres (out of about a million acres of total land) in the watershed. Once the map of the areas was complete, staff worked with faculty and students at the University of Michigan School of Natural Resources and Environment to develop a computerized model to rank them.

The ranking criteria include:
• Size
• Whether wetlands are on the site
• Whether rivers or lakes are on the site
• The potential for the site to contain groundwater recharge areas
• The potential for the site to harbor a high diversity of ecosystems (determined indirectly by measuring diversity of the site’s geology and topography)
• The potential presence of high value remnant ecosystems such as lakeplain prairie

Remaining natural areas in Dexter Township

Remaining natural areas in Dexter Township

Funding to preserve natural areas is limited. The map provides one tool for prioritizing funding to preserve the best natural areas first, before encroaching development engulfs them forever. Programs like the City of Ann Arbor’s Greenbelt millage, where communities are attempting to save the best natural areas through purchase of development rights or outright acquisition, will find the map useful. Other communities have used a similar map that Livingston County Planning Department staff adapted from the HRWC map to enact ordinances to require a permit before development in the areas occurs.

Kingfishers hunt and live along the river system.

Kingfishers live and hunt along the Huron and its tributaries

Download the Bioreserve Map. With Adobe Acrobat, you can zoom in to see the detail in your area of interest by using the magnifying glass icon on your Acrobat toolbar.} If you are interested in the map and are not able to download it, please contact Kris at 734/769-5123 x607 or

The Table of Scores and Rankings lists all the Bioreserve Sites, their total score and scores for each ecological criteria, and how they reanked overall and for each ecological criteria.
Table of Scores and Rankings, xls file, 656kb
Table of Scores, pdf 259kb
Table of Rankings, pdf 187kb

Bioreserve scores explained, 2007 59kb, explains how HRWC created the scores and rankings.

Rapid Ecological Assessment of Natural Areas

To allow us to obtain more information about these sites and to further identify those of the highest quality, we created the rapid ecological field assessment method. HRWC adapted the method from assessments performed by professional ecologists at the Michigan Natural Features Inventory (MNFI), making it general enough that volunteers with a half-day of training will be able to complete it, but detailed enough to glean meaningful information about the ecological quality of the site. Volunteer teams walk the site and fill out separate forms for wetlands, forests, grasslands, and creeks. The forms include questions about the kinds of plants growing on the site as well as vegetation structure (e.g. tree size distribution, percent cover of native vs. invasive plants), soils, and signs of human disturbance.The information from the forms is then inputted into a database, which computes scores for ecological integrity and levels of human disturbance for each site.

Results from the field assessments are shared with property owners, land conservancies, and local communities to aid in planning and preservation efforts.

Here is an example of the report that we create for each assessment.  We send the report to the property owner, the community, and the local conservancy.

Help Us Assess and Protect Natural Areas

Learn about field ecology, get outside, and help us assess and protect the natural areas of the watershed. Join volunteer teams to perform field assessments on the bioreserve sites.  Contact Kris at 734/769-5123 x607 or to find out more and get on the list for the next training session.  Also check out the field assessment volunteer web site , which includes all the instructions and forms you will need to participate.

Plant ID experts needed!

If you are experienced in plant identification, we especially need your help! Every team will need at least one “expert” (someone who has some experience with identifying plants). If you have had a plant identification class, or have become familiar with wildflowers, grasses, and trees over time spent hiking this beautiful watershed, we’d love your help!

LANDOWNERS: Learn About Your Natural Area Property

Take a look at the Bioreserve Map. Are portions of your property on the map? Do you think they should be? HRWC would be delighted to help you find out more about the natural areas on your property. This information can help you make decisions about maintaining your land, including developing options that could provide tax incentives for conserving high quality areas. An assessment will give you a base knowledge about what natural features exist and the benefit they may provide.

Please contact Kris if you are interested in learning more about your property


HRWC is seeking partnerships with local governments, conservancies, and parks departments to actively pursue strategies to permanently protect high quality natural areas. HRWC will work with partners in recruiting volunteers to assess sites, holding training sessions, and developing ordinances and policies to protect natural areas.

Please contact Kris if your community or organization is interested in working with HRWC to protect natural areas.

734/769-5123 x607 or

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