Old Cahokia Creek
Judy's/Burdick Branch
Brushy Lake
Spring Lake
Cahokia Mounds
Elm Slough
Dobrey Slough
Mullens Slough

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St. Louis District East St. Louis & Vicinity Interior Flood Control and Ecosystem Restoration Project February 2, 2000

The Old Cahokia Creek scenario currently consists of 18 action alternatives.

Location The project area is in Madison County. The floodplain component lies parallel to the bluff between the Cahokia Creek Diversion Channel and I-270, and consists of the remnants of Cahokia Creek and its adjacent floodplain. The "Bluff 1" watershed, to the north of Judy's Branch, comprises the upland component.

Purpose The purpose of this scenario is three-fold: 1) to restore Cahokia Creek and its adjacent forested floodplain to presettlement (ca. 1800) conditions, to the maximum extent practicable; 2) to minimize upland erosion and manage sedimentation in the "Bluff 1" watershed; 3) to create temporary storage areas for storm events to reduce flood damages within the County Ditch watershed (with a focus on Sand Road and vicinity).

Features Under Evaluation Each action alternative shares these features:

1. Restoration of the Cahokia Creek channel - segments of historic channel that have been filled over the years would be reopened, and existing channel areas would be excavated to remove accumulated sediment, to recreate a floodplain stream that once flowed from north to south;
2. Creation of a continuous forested zone along Cahokia Creek - trees would be planted where they currently do not occur on both sides of the creek;
3. Construction of an earthen berm along Cahokia Creek - this low berm would be located along the edge of the forested zone on the west side of Cahokia Creek to contain overflow from the channel; remnants of such a berm still exist in some areas.

1. Upland vs. bottomland sediment detention - upland sediment would be detained either in the uplands, by constructing about 10 new dry detention basins in the "Bluff 1" watershed, or in the bottoms in existing ditches and in the Cahokia Creek channel;
2. Length of channel restoration - two lengths of channel restoration are being considered; the shorter one extends north from I-270 along the creek for a distance of about 2.9 miles; the longer option extends all the way to the diversion channel (about 4.2 miles);
3. Augmentation vs. no augmentation of stream flows - a new pump station built at the diversion channel would be used to augment low stream flows for environmental purposes, and the pump would be reversible to facilitate removal of storm water during large rain events;
4. Width of forested corridor - on each side of the creek, widths of about 165 feet (50 meters), 245 feet (75 meters), and 330 feet (100 meters) are being considered.

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St. Louis District East St. Louis & Vicinity Interior Flood Control and Ecosystem Restoration Project February 2, 2000

The Judy's/Burdick Branch scenario currently consists of 8 action alternatives.

Location The project area is in Madison County. The floodplain component is southeast of the junction of I-255 and Route 162, at the confluence of Judy's Branch, Burdick Branch, and Cahokia Canal. The Judy's Branch, Burdick Branch, and "Bluff 1" watersheds comprise the upland component. In the floodplain, much of the project area lies at the southern end of historic Rattan's Prairie, a 15,000-acre wet prairie once located in the northeast part of the American Bottoms.

Purpose The purpose of this scenario is three-fold: 1) to restore presettlement (ca. 1800) floodplain plant and animal communities and flooding conditions, to the maximum extent practicable, using stormwater from the Judy's, Burdick, and "Bluff 1" upland tributaries; 2) to minimize upland erosion and manage sedimentation in the Judy's, Burdick, and "Bluff 1" watersheds; 3) create temporary storage areas for storm events to reduce flood damages within the Cahokia watershed.

Features Under Evaluation Each action alternative shares these features:

1. Creation of a habitat area with earthen ring levee, to contain the 100-year stormwater event delivered by Judy's and Burdick Branches combined;
2. Modification of the existing levee along the south side of Burdick Branch to direct the 100-year stormwater event from the two bluff tributaries into the new habitat area;
3. Creation of a 330-foot (100-meter) wide prairie buffer around the perimeter of the habitat area on its west, south, and east sides;
4. Creation of a 330-foot (100-meter) wide forested corridor along the north side of Burdick Branch, extending from Cahokia Canal to Route 157.

1. Upland vs. bottomland sediment detention - upland sediment would be detained either in the uplands, by constructing about 23 new dry detention basins in Judy's Branch watershed, 4 in Burdick Branch watershed, and 4 in "Bluff 1" watershed, or in the bottoms in the channels of Judy's and Burdick Branches, and in a sediment detention basin within the new habitat area;
2. Size of habitat area - small (131 acres), medium (230 acres), and large (350 acres) areas are being considered; to accommodate the volume of a 100-year storm event, extensive excavation within the habitat area would be required for the small area, moderate excavation for the medium area, and essentially no excavation for the large area;
3. Type of vegetation within the habitat area - wet prairie or marsh are being considered.

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St. Louis District East St. Louis & Vicinity Interior Flood Control and Ecosystem Restoration Project February 2, 2000

The Brushy Lake scenario currently consists of 12 action alternatives.

Location The project area is in Madison County. The floodplain component is east of Horseshoe Lake, and is bounded by Cahokia Canal on the west, I-255 on the east, and I-55/70 on the south. The Schoolhouse Branch and Snyder Ditch ("Bluff 3") watersheds comprise the upland component. In the floodplain, much of the project area is an old meander scar of the Mississippi River. Two centuries ago, Cahokia Creek flowed through this area, and forest was the predominant type of vegetation.

Purpose The purpose of this scenario is three-fold: 1) to restore presettlement (ca. 1800) floodplain plant and animal communities and flooding conditions, to the maximum extent practicable, using stormwater from Schoolhouse Branch, Snyder Ditch, and Cahokia Canal; 2) to minimize upland erosion and manage sedimentation in the Schoolhouse Branch and "Bluff 3" watersheds; 3) to create temporary storage areas for storm events to reduce flood damages within the Cahokia watershed.

Features Under Evaluation Each action alternative shares these features:

1. Creation of a 710-acre forested habitat area, to contain the 100-year stormwater event delivered by Schoolhouse Branch and Snyder Creek combined;
2. Modification of the existing channels and levees of Schoolhouse Branch and Snyder Ditch to deliver the 100-year stormwater event from these two bluff tributaries into the new habitat area;
3. Restoration of the historic Cahokia Creek channel within the habitat area - segments of channel that have been filled would be reopened, and existing remnants would be excavated to remove accumulated sediments, to recreate a floodplain stream that once flowed from north to south.

1. Upland vs. bottomland sediment detention - upland sediment would be detained either in the uplands, by constructing about 15 new dry detention basins in Schoolhouse Branch watershed and 2 new basins in "Bluff 3"watershed, or in the bottoms in the channels of Schoolhouse Branch and Snyder Ditch, and in a sediment detention basin within the new habitat area;
2. Type of channel modification in Schoolhouse Branch and Snyder Ditch - three kinds of channels are being considered: grass sides and earthen bottom, concrete sides and earthen bottom, and concrete sides and bottom;
3. Presence or absence of prairie filter - under the bottomland sediment detention option, a 330-foot (100 meter) wide vegetative buffer would be established in the habitat area outside the detention basin, and would consist of prairie plantings to intercept sediment carried by stormwater overtopping the basin.

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St. Louis District East St. Louis & Vicinity Interior Flood Control and Ecosystem Restoration Project February 2, 2000

The Spring Lake scenario currently consists of 21 action alternatives.

Location The Spring Lake project area is the largest of all those under consideration, and it spans both Madison and St. Clair Counties.
The floodplain component consists of three major areas, in addition to Harding Ditch:

1. Cell 1 (bounded by Forest Boulevard to the north, I-255 to the east, Bunkum Road to the south),
2. St. Clair Farms (bounded by I-64 to the north, Harding Ditch and I-255 to the east, St. Clair Avenue to the south),
3. Indian Lake (bounded by I-55/70 to the north, Route 111 to the east, Collinsville Road to the south, Route 203 to the west.

Purpose The purpose of this scenario is three-fold: 1) to restore presettlement (ca. 1800) floodplain plant and animal communities and flooding conditions, to the maximum extent practicable, using stormwater from both Canteen and Little Canteen Creeks; 2) to minimize upland erosion and manage sedimentation in the Canteen and Little Canteen Creek watersheds; 3) to create temporary storage areas for storm events to reduce flood damages within the Cahokia and Harding watersheds.

Features Under Evaluation Each action alternative shares these features:

1. A habitat area within Cell 1 (370 acres), St. Clair Farms (180 acres), and Indian Lake (620 acres), to contain the 100-year stormwater event, and earthen berms where necessary around these areas to contain this event;
2. Construction of a new Canteen Creek relief channel, to carry the 100-year stormwater event from Canteen Creek watershed into Harding Ditch;
3. Modification of Harding Ditch, from Route 157 to Cell 1 to carry the 100-year stormwater events from Canteen and Little Canteen Creek watersheds, and from Cell 1 to St. Clair Farms to carry the 100-year stormwater event from Little Canteen Creek watershed;
4. Construction of a new Fairmont City Ditch, from Cell 1 to Indian Lake to carry the equivalent of a Canteen Creek 100-year stormwater event;
5. Creation of a 330-foot (100-meter) wide forested corridor along both sides of Harding Ditch, between Cell 1 and St. Clair Farms;
6. Drainage of permanent water from dead timber north of Forest Boulevard within the Cahokia Mounds State Historic Site - standing water within a 35-acre tract of dead (drowned) timber would be drained and appropriate tree species planted.

1. Upland vs. bottomland sediment detention - upland sediment would be detained either in the uplands, by constructing about 46 new dry detention basins in Canteen Creek watershed and 23 new basins in Little Canteen Creek watershed, or in the bottoms in the channels of Harding Ditch and Canteen Creek;
2. Type of channel modification in Harding Ditch - six kinds of channel modifications are being considered. The first four retain berms alongside the channel: 1) concrete sides and earthen bottom, 2) concrete sides and bottom, 3) grass sides and earthen bottom, 4) rip-rap sides and earthen bottom. In addition to channel modifications, the last two involve moving the berms away from the channel to create a "floodplain": 5) "floodplain" with concrete sides and earthen bottom in the channel, 6) "floodplain" with riprap sides and earthen bottom in the channel. Not all options apply to each reach of Harding Ditch.
3. Degree of excavation in Cell 1 and St. Clair Farms - to accommodate the 100-year stormwater event in these two areas, excavation would be required. One option is extensive excavation in Cell 1 and none in St. Clair Farms, the other is minimal excavation in both areas. No excavation would be required at all in Indian Lake;
4. Type of vegetation within the habitat areas - various types are being considered, depending on the excavation option:
   Cell 1 - marsh for both excavation options,
   St. Clair Farms - prairie or forest are being considered under the no excavation option, and marsh for the excavation option.
   Indian Lake would remain constant across all alternatives. In general, existing habitats would be preserved. Remnants of Cahokia Creek would be reopened to create a flowing floodplain stream, and trees would be planted along both sides of the channel to create a continuous forested corridor 330 feet (100 meters) wide. Impaired drainage at the northern end would be improved and standing water removed to allow forest to become reestablished.
   Under the "floodplain" option, prairie would be planted along the Harding Ditch channel.

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St. Louis District East St. Louis & Vicinity Interior Flood Control and Ecosystem Restoration Project February 2, 2000

The Cahokia Mounds scenario currently consists of 12 action alternatives.

Location Cahokia Mounds State Historic Site, in Madison and St. Clair Counties, is the location for this scenario. There is no upland component. The project area lies within historic Cold Prairie, a 15,000-acre prairie once found in the southeast part of the American Bottoms.

Purpose The purpose of this scenario is to restore presettlement (ca. 1800) prairie plant and animal communities, to the maximum extent practicable.

Features Under Evaluation Each action alternative involves the restoration of a total of 525 acres of high quality prairie in the Cahokia Mounds State Historic Site.

In addition, the action alternatives consist of various combinations of the following 2 parameters:

1. Rate of restoration - replacement of hay production areas with prairie plantings would be completed within a 5, 10, 25, or 50 year time period; in terms of area, these rates correspond to an average of 105, 52.5, 21, or 10.5 acres planted per year
2. Type of maintenance for prairie vegetation - three maintenance options are being considered.
   1. Burn - burning only; the entire prairie is burned every 3 years on a rotational cycle (a portion is treated every year);
   2. Burn/mow - burning and mowing; the entire prairie is mowed every 2 to 3 years in a 5-year period, and burned once every 10 years; both treatments are on a rotational cycle;
   3. Mow - mowing only; the entire prairie is mowed once every 3 years on a rotational cycle.

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St. Louis District East St. Louis & Vicinity Interior Flood Control and Ecosystem Restoration Project February 2, 2000

The Elm Slough scenario currently consists of 5 action alternatives.

Location The project area is northeast of Horseshoe Lake in Madison County. Route 111 bounds it on the west, Route 162 to the north, and I-255 to the east. There is no upland component. Much of the project area is an old meander scar of the Mississippi River, and forest was the predominant type of vegetation two centuries ago.

Purpose The purpose of this scenario is two-fold: 1) to restore presettlement (ca. 1800) floodplain plant and animal communities and flooding conditions, to the maximum extent practicable, using stormwater from both Long Lake and Mitchell Ditch; 2) to create temporary storage areas for storm events to reduce flood damages within the Long Lake watershed.

Features Under Evaluation Each action alternative shares these features:

1. Creation of a 670-acre forested habitat area to contain the 100-year stormwater event delivered by Long Lake and Mitchell Ditch combined, and earthen berms where necessary to contain this event;
2. Modification of the existing channels south of Route 162 that carry Long Lake and Mitchell Ditch into the area - the drainage pattern would be changed to allow storm water from these waterways to sheet flow from the east to the west; culverts under Route 162 and the adjacent railroad would be modified.
3. Creation of a forested zone along the channel modifications - trees would be planted alongside the modified channels.

1. Various intensities of improvement to existing forest - three levels of intensity would be considered: no improvements, simple, and intensive; simple improvements would consist of selective thinning and planting of underrepresented tree species in the existing drier forest; extensive improvements would involve drainage of existing dead (drowned) timber and plantings of appropriate tree species;
2. Presence or absence of prairie buffers - a vegetative buffer consisting of prairie plantings would be established before the main forested habitat area to intercept sediment carried by flows from Long Lake and Mitchell Ditch.

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St. Louis District East St. Louis & Vicinity Interior Flood Control and Ecosystem Restoration Project February 2, 2000

Location The project area is north of Horseshoe Lake, near Granite City and Pontoon Beach, Madison County. It lies north of Pontoon Road and east of Maryville Road. There is no upland component. Dobrey Slough is a relatively small historic slough of the Mississippi River without any natural tributaries leading out of it. Historic vegetation of the slough apparently was non-woody.

Purpose The purpose of this scenario is two-fold: 1) to restore presettlement (ca. 1800) floodplain plant and animal communities and flooding conditions, to the maximum extent practicable, using local stormwater; 2) to create temporary storage areas for storm events to reduce flood damages in the neighborhoods adjacent to Dobrey Slough, in the Long Lake watershed. This scenario addresses only surface flooding and not below-ground flooding due to localized high groundwater conditions.

Features Under Evaluation Each action alternative shares these features:

1. Creation of a 55-acre marsh habitat area to contain the 100-year stormwater event delivered by local runoff; adjacent to the southern end of the historic slough, excavation would be required to increase the storage area, and existing drainage structures located under the railroad embankment would need to be modified;
2. Creation of a continuous forested zone along Dobrey Slough - on one side only (north side), trees would be planted where they currently do not occur along the slough.

1. Width of forested corridor - widths of about 165 feet (50 meters), 245 feet (75 meters), and 330 feet (100 meters) are being considered.