Au (Ahhhhh) Sable River

The Au Sable is a major tributary to Lake Huron. It drains a north-south basin that includes 1,932 square miles in north-central lower Michigan. The basin is approximately 90 miles long and 10 to 30 miles wide. The river basin is partially within the Huron National Forest. The watershed is located within parts of the following eight counties: Otsego, Crawford, Roscommon, Montmorency, Oscoda, Ogemaw, Iosco and Alcona. The area includes some 30 administrative townships. The incorporated cities of Grayling and Roscommon are within the watershed, as are numerous unincorporated villages, including Mio, the seat of Oscoda County, and Oscoda. Gaylord, a major community, sits at the headwaters of both the Sturgeon and Au Sable rivers. Drainage to the south out of Gaylord makes its way to Lake Huron through the Au Sable River system. The river basin is readily accessible by all major forms of transportation. Interstate highway 75 is a major Michigan north-south artery. It provides ready access to the Grayling area from all of southern Michigan. Highway 23 is a major Lake Huron shore route serving the Oscoda area and providing access from all of southeastern Michigan. State highways 72, 33, and 65 are intermediate routes serving the entire river basin. Aside from several very small areas with difficult access, the basin has a heavily developed system of federal, state, county and Forest Service roads. The Au Sable River has the reputation for being an outstanding trout stream as well as being popular with canoeists, homeowners and other recreationists. The many outstanding natural values possessed by this river have resulted in 23 miles of the mainstream being designated by the United States Congress as a Scenic River under the Federal Wild and Scenic Rivers Act (PL 90-542). The Natural River Act (Part 305, P.A. 451 of 1994) authorizes the Natural Resources Commission to establish a system of "natural rivers" in the state to provide for their preservation, protection and enhancement. Section 30502 of the Natural River Act states, in part, that: "The commission, in the interest of the people of the state and future generations, may designate a river or portion thereof, as a natural river area for the purpose of preserving and enhancing its values for water conservation, its free flowing condition and its fish, wildlife, boating, aesthetic, flood plain, ecologic, historic and recreational values and uses". It is recommended that the mainstream of the Au Sable River and selected tributaries be designated as a "wild-scenic” river under authority of Natural Rivers, Part 305, P.A. 451 of 1994 is of a wild character with wild or forested borders, in close proximity to human development. The wild aspect may be relatively broad or confined to a narrow ribbon. The Au Sable River drains an area of 1,932 square miles and drops approximately 650 feet from its point-of-origin. The average discharge at the Mio Dam from a drainage area of 1,100 square miles equals 990 cubic feet per second (cfs). On a direct drainage area ratio, the average discharge at the mouth is estimated to be 1,600 cfs. There are approximately 476 miles of streams in the Au Sable River system. The mainstream is about 129 miles long and includes 37 miles of impoundments. There are six existing hydro-electric power plants in the Au Sable River basin, with a total installed capacity of 41,000 kilowatts and an average annual energy output of 139,000 megawatt hours (MWH). All the power plants are operated by an investor owned utility company - Consumers Energy Company of Jackson, Michigan. The six reservoirs were constructed during the period of 1911 through 1924. The Au Sable River mainstream originates at the junction of Kolka and Bradford creeks, approximately 2 1/2 miles north of the town of Frederick in northwestern Crawford County. The mainstream above Grayling has a narrow winding channel with occasional beaver dams and debris clogged passages. Although safely floatable from Cameron Road Bridge, it is arduous canoeing and not popular. Shallow water and partly submerged debris also discourages canoe use. The stream gradient averages 4.0 feet per mile. The stream gauging station at Grayling indicates an average discharge of 73.5 cfs -- or approximately four percent of the total discharge at Oscoda. Discharge increases rapidly between Grayling and Mio. Stream flow measurements in July 1972 indicate: a discharge of 76 cfs at Grayling; 141 cfs at I-75; 230 cfs at Stephan's Bridge; 511 cfs at Beaver Bend; and 862 cfs at Mio. The increase reflects East, North, and South Branch inflow as well as groundwater flow. Current speed below Grayling varies from 2 to 4 mph depending on depth, bottom conditions, and gradient. The gradient is 4.71 feet per mile below Grayling. The river follows an occasionally narrow, sinuous course before straightening at McMaster's Bridge. It has sufficient depth for canoeing at all seasons, but heavy ice may be encountered above this area during severe winters. There are many short sections of fast riffle current, sharp turns, and occasional sweepers and down debris which constitute challenging and relatively safe floating for the novice and beginner canoeists. The Mio to Alcona 23 mile segment was the only portion of the Au Sable River system designated by the U.S. Congress as a component of the Federal Wild and Scenic River system. From Mio to Alcona Pond, the river has occasional large curves and many short relatively straight stretches. The river is wide, flows at a moderate speed, and has sufficient depth for safe, pleasant canoeing by beginner-novice level canoeists. It is free of all debris and sweepers but may be iced over below McKinley during severely cold winters. There are occasional short stretches of riffle. Current velocity may average 2 to 4 mph depending on channel configuration and discharge increases from 982 cfs (average-1966) at Mio to 1,350 cfs (average 1909-1914) at Alcona. The increase is attributable to inflow from Cherry, Perry, Comins, Wolfe and Loud creeks, plus groundwater sources. Although the Mio Dam is still used by Consumers Energy Company for power generation, an agreement between the DNR and Consumers Energy in 1966 set Mio Dam discharge equal to pond inflow. Therefore, river discharge above and below the pond are equal and power generation should not affect the lower river flow rates. Below Alcona Dam, the Au Sable flows through many large gradual curves with few straight stretches over 1/4 mile long. It is a large river at this point and has sufficient depth and width for easy canoeing. However, during power generation discharge at Alcona, the water level may rise up to four feet and create somewhat hazardous conditions for inexperienced canoeists. Although this section is relatively free of debris, the current becomes quite strong forming deep eddies and some turbulence. The power generating schedule at Alcona and Foote dams, being dependent on waterflow, season, and power demand, is somewhat unpredictable. Therefore, water levels are also unpredictable. They maintain a partial flow of 14 cfs or 30 percent of full throttle 24 hours per day to provide water for the river below. This flow rate is something less than the inflow into the reservoir above. Twice per day at approximately 10:00 AM and 3:00 PM, the discharge is increased considerably to meet power demands and may run until noon and 9:00 PM respectively. Average discharge at Alcona between 1909 and 1913 was 1,444 cfs without the influence of Alcona Reservoir. Discharge extremes during that same period were 4,800 cfs and 850 cfs. Discharge can be expected to range form 1,480 cfs to 3,650 cfs. Conditions similar to those below Alcona also prevail below Foote Dam. However, the lower river has considerable amounts of sunken and partly submerged debris which is largely covered during high water. Average annual discharge at Oscoda in 1966 was 1,937 cfs. Discharge at Foote Dam during power generation ranges from 1,480 to 3,650 cfs. The South Branch above Roscommon follows a slow sinuous course through lowlands. The channel is narrow and frequently choked with downed trees, debris, and overhanging shoreline vegetation. Although safe, it is arduous, slow and unattractive to most canoeists. Below Roscommon, the river has adequate depth and width to provide safe, pleasant canoeing experiences. It has many gentle bends, several narrow channels and many short interesting stretches of riffle. It is relatively free of debris that would hinder canoeing, but may have several shallow stretches with exposed rock during very dry seasons. August 1972, stream discharge at Chase Bridge, six miles below Roscommon was 91 cfs; Smith Bridge 136 cfs, Oxbow 178 cfs, and at the mouth, 133 cfs. The lower river below Oxbow actually loses flow from infiltration and evaporation. An average annual discharge at Smith Bridge and the mouth would be 229 cfs and 252 cfs respectively. The stream gradient from Roscommon to the mouth is 4.4 feet per mile. The North Branch above Lovells progresses from a slow, narrow meandering stream, clogged with shoreline vegetation, to a much ider shallow river at Lovells. The vegetation, debris and shallow ater make this section very difficult to navigate with a canoe. Below Lovells, the first 1/2 mile may be shallow and difficult during normal seasons but can be floated safely. The lower river has adequate depth and width for canoe use. Streamflow measurements taken in July 1971, indicate discharges of 16 cfs at Old State Road; 79 cfs at the Ford; 125 CFAs at Blackhole; 161 cfs at Lovells; 204 cfs at Kellogg; and 344 cfs at the mouth. Stream gradient from Dam #2 to the mouth is 8.7 feet per mile. Highly stable water flows of very high quality water may be the single most significant trait of the Au Sable River. The coarse sand-gravel composition of the watershed allows rapid infiltration of water and tends to level precipitation into a steady groundwater contribution to stream flow. Water flows vary insignificantly throughout the season because most inflow is from groundwater sources. This spring seepage is also an important factor to help maintain lower stream temperature during the summer months. However, river flow rates may respond to very rapid snowmelts and some sections will experience increases in water level and turbidity. High or dangerous water conditions are rare. The greatest river discharge occurs during April following snowmelt with an average discharge at Mio from 1961 to 1965 of 1286 cfs. The average discharge drops to 1,163 cfs in May; 864 in June and 746 in July as compared to annual average of 990 cfs. In addition to a stable flow, the water quality of the Au Sable River system is very high when compared to other rivers in the state. Using the standardized Water Quality Index, the Au Sable River at its mouth is shown to average 85.9. Water quality index consists of averaging numerical values from chemical, physical and biological parameters collected from monitoring stations on the river. Parameters used in establishing the WQI are: dissolved oxygen (D.O.), Fecal Coliforms, PH, Biochemical oxygen demand (BOD5), NO3-N (nitrogen), PO4-P(phosphates, temperature, turbidity and dissolved solids. Water quality of the Au Sable river system is protected for the following uses: (a) total body contact recreation; (b) agriculture; (c) industrial water supply; (d) navigation; and (e) public water supply. Most of the mainstream and tributaries, at least above Loud Dam are classed as cold water trout streams. Any designated stretches of the river system will governed by the "nondegradation" rule of the Water Resources Commission's water quality standards. The topography of the Au Sable river basin is rolling to flat. Maximum elevation above sea level is approximately 1,447 feet in the extreme western portion and the minimum elevation is approximately 600 feet on the extreme eastern end. The river basin has an approximate fall of 669 feet. The western half of the river basin is generally flat to slightly rolling and the eastern half is flat--broken only by stream channels. Low swamps and marshes are common throughout the western half of the river basin--particularly in the river headwaters and margins. The eastern half is comparatively well drained and has relatively few lowland areas. The Au Sable's outstanding scenery is presented in dramatic fashion by constantly changing topography. Each landform situation offers an attractive and varying display of geologic and vegetative conditions. High bluffs, lowland swamps, gentle slopes, river banks, upland plateaus and marshland often fluctuate over relatively short distances and provide background for the river's outstanding scenic resources. The watershed, like all others in the State of Michigan, shows the effects of glacial action. It lies in an area once covered by the Michigan Lake of the Pleistocene glacier and is characterized by glacial moraines and outwash plains. The basin is underlain by glacial drift up to several hundred feet deep with no outcroppings of bedrock material. The morainal areas are hilly with bold detached ridges. Outwash areas are relatively flat undulating plains except where cut by stream channels. The ancient lake bed area west of Oscoda is extremely flat and was covered during ancient glacial periods by the waters of Lake Huron. There are excellent examples of the effects of the ice, water, and wind on the landscape. Kettle lakes, oxbow lakes, eskers, drumlins, kames, terraces, sandblows, and deltas can be observed in the watershed. The soils of the Au Sable River are situated on three main levels--the flood plains, at the terrace level, and the outwash plain. The outwash plain was deposited as the glaciers started to recede. As the glaciers receded further and the amount of water increased, the Au Sable began to downcut through its own outwash plain, thus producing the terrace level and the present level of the river. The outwash plain is primarily a deep medium sand soil with very little organic soil development. Because of its sandy nature, water percolates through it rapidly, thus causing a water scarcity for plant life. The principle vegetation is jack pine and oak. There are some areas that have more nutrient and moisture status that support quaking aspen, red pine, and higher site oak and jack pine. On the terrace level, gravel predominates most of the soils. This gravel is found, in many cases, throughout the soil profile, ranging from 5 to 30 percent of the soil material; often it starts at 18 to 24 inches and continues throughout the profile. The texture of the layer above the gravel is sand, resembling the weakly developed soil of the outwash plain. The vegetation of this soil is jack pine and oak. Along this terrace there are many areas of well-drained, heavy textured soils and more strongly developed sands that support quaking aspen, white pine, and more productive red pine. The soils in the flood plain are mostly poorly drained organics. The organic layer varies from about 6 inches to 5 feel deep. The mineral layers below are usually sand with a few having sands of finer textured materials just below the organic layer. White and black spruce, balsam fir, northern white cedar, and tag alder occur on these soils. In draws and potholes on the terrace, similar soils also occur with lowland hardwoods such as elm, ash, and paper birch. Between the flood plain and terrace, there is often a transition zone containing the moderately well-drained and somewhat poorly drained soils which are sand or heavy textured. Quaking aspen, paper birch, and balsam fir dominate on these areas. The heavier textured soils that are better drained that might be used for farming occur only in small areas, and on steep slopes not conducive to farming. There is some evidence of small gravel pits, but apparently none have been commercially developed. Vegetation is the primary contribution toward providing and protecting the Au Sable's outstanding values. The river's high scenic quality results from constantly changing vegetative types and conditions--all remaining in a relatively natural condition and in apparent harmony with other natural elements. Vegetation shades the water thereby helping maintain low water temperatures. Vegetation softens incongruities and provides habitat and food for wildlife. Soils are stabilized and developed by vegetation. The great diversity of trees, shrubs, ferns, small flowering plants, lichens, mosses and mushrooms offer an interesting variety of form, color and texture--often changing with each season. Vegetation along the Au Sable River is generally typical of east central Michigan. However, two features combine to produce distinctive local plant communities within the river zone. First on the stream terraces, water from the river and local aquifers permit a greater variety of growth than that found on the surrounding plains. There is also a preponderance of silty and organic soils found on the river terraces with their associated different vegetative types. Secondly, the river winds through a variety of landforms and soil types--each having its own distinct vegetative cover. This vegetative description is not all encompassing, but describes dominant plants in either the superstory or substory for the various landforms. Over 80 percent of the watershed is forested. Major vegetative types include aspen, jack pine, red pine, oak, maple, beech, birch, and pine plantations. Lowland conifers include white cedar, balsam fir, tamarack and spruce. Original cover on the better-drained sites was predominantly red and white pine and northern hardwoods which were virtually eliminated during the early logging era. Nearly all stands are now in second or third growth cover. Vegetative types are predictable and ecologically diverse, depending on topographic situations, particularly in the river zone. The well-drained sites support stands of northern hardwood, aspen or red, jack, and white pine. They often cover extensive upland areas, are productive and generally even-aged. They provide good summer range for wildlife and support many varied forms of ground vegetation. Lowland areas have higher water tables and poor drainage. Lowland conifers, hardwoods and shrubs dominate these sites. These lowland areas tend to be less extensive, are spotty, follow stream courses and are densely vegetated. They tend to be excellent deer winter range and have rich variety of ground vegetation. The Au Sable River basin offers a climate typical of the state's "north country". The warm days and cool nights offer a pleasant haven for vacationers. The winters provide an excellent climate for skiers, snowmobiling, and other winter sports. Weather data for the Au Sable basin indicates a record high of 112 degrees F with the record low of -47 degrees F, both recorded at Mio. A temperature of 100 is reached on an average of once in 10 years. At the other extreme, one can expect temperatures to fall below zero an average of 25 days per year. The average yearly temperature for the basin is 43.1 degrees F. Precipitation is heaviest during the summer season averaging 63 percent of the annual total during the six month period, April through September. Heaviest rainfall for the basin is in September which shows an average of 3.38 inches. Lowest rainfall occurs in February with an average of 1.30 inches. Annual precipitation averages 28.30 for the 24 years of record. Summer skies tend to be generally free of cloud cover and westerly breezes are nearly constant. Winter skies are generally cloud covered and windy.Support for including the Au Sable River under the Natural River Act comes from a variety of organizations and interests.