Baseline Assessment of Stormwater and Snowmelt Runoff to the Au Sable River from the Grayling Subwatershed

Introduction

Renowned for its superb angling and canoeability, northern Lower Michigan's Au Sable River system has long reigned as a major destination for outdoor enthusiasts across the upper Midwest and beyond. As a regional economic asset its intrinsic value far exceeds our ability to measure it.

Of paramount importance, the system's high quality water and diversely vegetated corridor provide superior habitat for fish and wildlife. Indeed, they are what drive its famous trout fishery, harbor a wide variety of aquatic and terrestrial fauna, and sustain its resplendent riparian setting. By definition, however, coldwater ecosystems like the Au Sable and its corridor are particularly prone to chronic, incremental impairment brought on by watershed degradation together with poorly controlled use. And rather than recipients of dedicated stewardship, such sensitive resources are often taken for granted, too frequetly become victims of benign neglect, and gradually lose their vitality.

Deeply troubled by local apathy over the Au Sable's slow but perceptible decline as a healthy and productive public asset, the nonprofit George A. Griffith Foundation of Grayling, Michigan, mounted an initiative in 1996 that it felt was long and unconscionably overdue. It did so in the not unreasonable expectation that others equally troubled about the future of such a unique endowment would quickly join in helping to underwrite this Foundation enterprise. That action entails a comprehensive baseline assessment of urban stormwater and snowmelt runoff into the Au Sable system from the greater Grayling area. It also represents a significant if not overriding adjunct to recently unfolding efforts of other groups working cooperatively to stem evident system damage being caused by a mixture of hypothesized factors.

Background

Located appealingly on the world-famous Au Sable River, Grayling and its immediate surroundings are being developed and inhabited at a pace unimagined a scant decade ago. As in many locales elsewhere in northern Lower Michigan, this area rings with the sound of accelerating development for residential, commercial, military, industrial, and recreational purposes. What we don't hear but readily sense and easily foresee are the inexorable effects of this development, not only in a greatly altered watershed but also in much heavier use of its limited and already stressed wildlife, fish, and water resources.

Collaborative efforts to reverse protracted degradation of the Au Sable system as trout habitat, spurred largely by private-sector interest and initiative, are now well underway. The focus during their first five or so years has been almost exclusively on managing the control and removal of sediment (sand), and on rehabilitating woody instream structure. Little attention has yet been paid to evaluating the performance of the expanding -- and world-class but now sputtering -- trout fishery itself, or to the matter of surface water quality as possibly affected by contaminated groundwater discharge and/or untreated urban runoff.

The prospect of chronic system damage attributable to nonpoint runoff pollutants worries many who live in the Grayling and Roscommon communities, or who visit them regularly to angle for trout in, or otherwise enjoy, system waters. Ominous changes in runoff rate and volume, i.e., increased `flashing' in the Au Sable's mainstream below Grayling, also elicit growing anxiety. Widespread publicity in recent years about urban runoff as the Nation's biggest threat to the quality and stability of its surface waters greatly reinforces these legitimate concerns. Even so, very little besides occasional spot checks by public agencies over the past quarter century has resulted in anything close to a solid, credible basis (1) for saying whether or not, to what degree, and at what rate runoff and runoffborne contaminants may be adversely affecting discharge patterns and accumulatively impairing system water quality, thence (2) for taking definitive positions from which to respond accordingly.

Action

In mid1996, the Foundation's board of directors elected to advance its modest financial capital by way of a public service aimed at filling this serious void in our intelligence about the Au Sable system. Following an extensive search for professional representation, it subsequently contracted in mid-1997 with McNamee, Porter & Seeley, Inc. of Ann Arbor, jointly with Dell Engineering, Inc. of Holland, both wellestablished Michigan consulting firms, to perform the subject assessment of urban runoff from the Grayling area. [Note: The Foundation's original request called for a similar effort in the Roscommon (Au Sable South Branch) area but the additional cost induced postponement of this option.]

The assessment consists of three phases: (1) assembly of background detail about local geology and surface drainage, earlier observations related to runoff physics and chemistry, and the present extent of impervious land cover; (2) development ad implementation of a runoff-monitoring and -sampling program; and (3) collection, analysis, and annotated display of baseline data for ready reference. Phase 1 began upon contract endorsement in June of 1997.

Life of the project will not exceed two years. Once data collecting (phase 3) begins, it will span one full year on a season-by-season basis, concurrently with the automated recording of ambient precipitation. At strategic locations in the Au Sable's mainstream and east branch above the Grayling subwatershed, and in its mainstream below, system flow rates and major physicochemical properties (temperature, dissolved oxygen, pH, and conductivity) will be monitored continuously by state-of-the-art sensing devices. Sampling the river's flowage automatically for a variety of its constituents (principal anions, trace metals, sediments, dissolved solids, bacteria, volatile and semivolatile organics, biocides, PCBs, etc.) will be spread evenly across the four seasons, taking place as well during spring snowmelt and instantaneously in response to subsequent storm events. Operation of all automatic samplers will be preprogrammed and flow-actuated, as well as synchronous through telemetric linkage. Supplemental sampling at major runoff outfalls may be dictated by a need to trace sources of contamination detected in downstream river samples. [Note: The Foundation also contemplates similar runoff and water quality assessments in the system's north and south branches as well as in the nearby Upper Manistee River.]

For the Foundation, local liaison with the contractor and coordination of onsite operations will be managed by the Huron Pines Resource and Development Area Council, Inc. in Grayling.

Results

The action so described promises the first-ever continuous, one-year-cycle picture of the Au Sable's (mainstream) flow, together with its physical, chemical, and biological properties, as affected by stormwater and snowmelt runoff from the urbanized Grayling area. The resulting hydrograph, thermograph, and `chemograph' will constitue invaluable baseline references, or indexes, against which future changes in the rate and volume of runoff, the heat load it bears, and the contaminants (including sediment) it conveys are to be gauged. Accordingly, they will be applied to demonstrate the effects of increasing impervious cover and compaction of the subwatershed's surface, identify and measure the influx of potentially harmful urbanization by-products, and thus possibly explain why ecosystem productivity has diminished or may do so in the foreseeable future. Most importantly, they will provide a credible factual basis from which the allocation of community assets in meeting the certain need to manage Grayling's stormwater and snowmelt discharge in the years immediately ahead can be objectively justified.

Cost

From the outset, the Foundation's board of directors insisted that this assessment be pursued in the most comprehensive, impartial, technologically up-to-date, and professional way feasible. Its estimated cost unmistakably reflects these conditions. Projections are as follows: phase 1, background examination, drainage reconnaissance, etc. -- $8,000; phase 2, monitoring and sampling strategy, instrument acquisition and placement, etc. -- $53,000; and phase 3, data collection, sample analysis, computerized observation display, etc. -- $81,000.

The Foundation boldly took the lead in addressing this urgent assessment need, fully anticipating that its total cost of roughly $142,000 would be shared by other like-minded individuals and groups, particularly those who appreciate the Au Sable's real as well as symbolic value. It offers this synopsis for the purpose of enlisting their underwriting support.

Contacts

Additional details for those wanting to help may be obtained by writing the Foundation at P.O. Box 502, Grayling, MI 49738, by telephoning or faxing its secretary at (517) 348-2608, or by telephoning its technical advisor at (517) 348-4075 or faxing him at (517) 348-7945. RWOL

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