Rock Island Ecological Services Office
Midwest Region

Draft 10/21/02, needs Bio’s review.



Description of Pool 13:

Pool 13 is the 34.2 mile segment of the Mississippi River extending upstream from Lock and Dam 13 at Fulton, Illinois to Lock and Dam 12 at Bellevue, Iowa. Bordered by the states of Iowa and Illinois, Pool 13 includes ____ acres of public lands and waters and has a total drainage area of 85,500 square miles. Although the project area is Pool 13, planning considerations extend to areas which impact pool resources, including watersheds, natural floodplains behind levees, and private lands within the pool.

Pool 13 encompasses much of the natural floodplain. Levee systems are adjacent to about five river miles in Iowa and four in Illinois. The one Illinois levee defines the Spring Lake area which is a previous agricultural drainage district now open to the river and managed for river habitats. The Green Island Levee and Drainage District (Iowa) is an active agricultural District but much of the unit is managed for river habitats by the State of Iowa. With the exception of the small towns of Bellevue and Sabula, Iowa, and Savanna, Illinois, the riparian environment is rural. The Maquoketa River (Iowa) is the major tributary, entering in the upper third of the pool. Smaller streams include the Apple and Plum Rivers (Illinois) and Smith Creek and Elk River (Iowa). The total watershed of tributaries entering the Pool is 3,100 square miles.

A distinguishing character of Pool 13 is the large unit of floodplain and riparian area, including sand prairie, which is encompassed within the Savanna Army Depot, a closed Military Reservation. Portions of this area are scheduled to be managed for natural resource values and this will include designation of the Lost Mound Unit within the National Wildlife Refuge system. A large expanse of open water upstream from lock and dam 13, approximately three by five miles in dimension, also characterizes the pool. Turbidity and sedimentation are serious problems and impacts are especially obvious in all backwater areas where deeper-water habitats are rare. Vegetation however, remains relatively abundant throughout the pool.

Public lands and waters include the Upper Mississippi River National Wildlife and Fish Refuge, Savanna Army Depot, General Plan lands of the Nine-Foot Navigation Project, Iowa DNR Green Island Wildlife Management Area and other lands and waters owned by the States of Iowa and lllinois.

Resource Problems and Issues:

1. Fine sediments are accumulating at accelerated rates within backwaters and other floodplain locations due to high-suspended sediment concentrations and the reduced sediment transport capability of the navigation project.

2. Habitats critical to migratory birds must be maintained, especially aquatic food resources and woodlands.

3. Coarse sediments, or bed load sediments, accumulate in side channels where they fill valuable habitats and restrict flow.

4. Elevated water tables favor moisture tolerant forest species, limit site potential for species diversity, and promote plant succession to moisture tolerant grasses.

5. Watershed discharges into Pool 13 contribute to significant water quality and habitat problems which affect natural resources. Issues and examples include accelerated sedimentation with associated nutrient and contaminate delivery (see 1 and 3 above) and urban and industrial discharge. More information is needed about discharges into Pool 13 and associated impacts.

6. Locks and dams 12 and 13 restrain fish passage between pools.

7. Information is needed to better assess and manage Pool 13 mussel populations.

8. The current water management regime, especially the avoidance of seasonal low water, removes much potential for periodic regeneration aquatic habitats.

Resource Opportunities:

1. Restoring the full range of bottom contour and depth (bathymetric diversity) within backwaters will address Resource Problem 1 discussed above. The river’s natural energy may be harnessed at select sites with features designed to (a) scour sediment, (b) maintain sediments in suspension to prevent accumulation, or (c) divert sediment laden. At sites protected from accelerated accumulation but where natural processes cannot restore desired bathymetry, dredging can replace natural cutting and scour. Watershed management with best management practices can limit soil loss and downstream sediment loads and reduce sediment problems.

2. Pool management which effectively maintains emergent and submersed aquatic vegetation and forests will insure availability of habitats critical to migratory birds (Resource Problem 2). Vegetation provides direct habitat benefits and positively influences other important resources, such as aquatic macroinvertebrates and fishes. Opportunities to restore or maintain aquatic vegetation include: (a) island maintenance or development to shelter aquatic areas, (b) water level management, especially to provide periodic low elevations, (c) actions within watersheds and the pool to lower turbidity and sedimentation rates, and (d) maintenance of critical backwater or floodplain habitats at select locations. Opportunities to maintain forest communities are discussed in item 4, below.

3. Design and construction of projects to utilize the river’s hydraulic energy to open or maintain side channels can be accomplished to mitigate Resource Problem 3. Opportunities include (a) erosion protection of key side channel shorelines, (b) experimental structures designed to alter flow and increase bathymetric diversity within side channels, (c) flow regulation into degraded side channels, and (d) development of bathymetric and sediment transport models for Pool 13 to aid analysis and project design. Dredging can also restore side channel productivity, and is especially appropriate when used in combination with techniques which sustain the desired condition.

4. Mitigating the long-term impacts of an elevated water table can help improve forest regeneration and tree species diversity at select sites (Resource Problem 4). Opportunities include (a) raising ground surface elevation, (b) use of intensive regeneration aids, (c) careful management of existing diverse stands, and floodplain edge sites, (d) experimental plots testing a variety of forest management techniques, and (e) examination of pool water management profiles and topography to identify sites with best potential for diverse forest management.

5. Collaboration with water quality authorities will provide information on watershed characters, such as sediment delivery from specific watersheds (Resource Problem 5). Opportunities to improve watershed impacts can include (a) collaborative efforts to reduce upland soil erosion, (b) improvements to lower tributary characters including bank erosion of coarse sediments, (c) supporting efforts to solve specific water quality problems, such as industrial discharges, and (d) initiation of needed monitoring if information is not available.

6. Modifications at Locks and Dams 12 and 13 can improve fish passage (Resource Problem 6). Opportunities include the design and construction of ladders or amending lock or dam operation.

7. A mussel inventory is needed to provide basic information on Pool 13 mussels (Resource Problem 7). Opportunities include (a) a collaborative inventory involving all agencies or (b) a contracted study funded by an applicable authority.

8. Timely water level fluctuation, planned within the constraints of the navigation system, can induce biological responses, which rejuvenate aquatic habitats (Resource Problem 8). Opportunities include periodic reduced summer water elevation designed to mimic natural summer low flow events.

Proposed Actions:

To facilitate planning and illustration, proposed actions are organized within geographical units. Geographical unit boundaries and the locations of actions proposed within Pool 13 may be located on the Desired Future Habitat Conditions maps, which follow this section.

Savanna Proving Grounds/Upper Pool 13:

Modify Dam 12 to introduce flow to the Crooked Slough Complex in Pool 13.

Restore depth for fish species by dredging into and within Crooked Slough Complex (May need to explore UXO concerns.

Pleasant Creek Bottoms:

Restore depth at select sites to improve bathymetric diversity.

Monitor completed Habitat Rehabilitation and Enhancement Project (HREP) features and insure project objectives are maintained.

Green Island Bottoms:

Expand moist soil and shallow aquatic wetland management, within the constraints of the Green Island Levee and Drainage District, to provide and ensure critical migratory bird habitats.

Smith Creek Watershed:

Complete a proposed HREP designed to reduce nutrient and sediment discharge into Brown’s Lake, improve water quality and extend deep water habitat values. Project features will include terraces, filter and buffer strips, riparian habitat development and sediment detention basins.

Advocate for continuing best watershed management practices.

Construct a wetland at the mouth of Smith Creek, designed to trap sediments and nutrients prior to their discharge into Brown’s Lake.

Brown’s Lake / Pin Oak Lake:

Monitor features of the completed HREP and insure that project objectives are maintained. Objectives include reduced sediment delivery, maintenance of deep water habitats and dissolved oxygen concentrations, and forest and wetland restoration.

Remove obstruction from the mouth of Pin Oak Lake to facilitate fish movement.

Reduce sediment and current introduction into Pin Oak Lake during high flow events with construction of a low deflection berm, simulating a natural levee.

Restore depth for fish species by dredging into and within the Pin Oak Lake.

Savanna Bay:

Restore forest community diversity by elevating select sites and planting to appropriate species. Utilize material from channel maintenance and backwater dredging projects.

Restore depth for fish species by dredging into and within Savanna Bay.

Monitor flow and sediment into the lake.

Running Slough / Sabula Lakes: Does Running Slough have another name on the charts? Yes, it is called Sabula Slough but not many people call it that.

Maintain flows through Running Slough. Monitor the log jam and open the site if necessary to maintain side channel characters.

Complete the proposed HREP for Running Slough/Sabula Lakes with project features including, side channel and backwater habitat restoration.

Spring Lake Complex:

Monitor features of the completed HREP and insure that project objectives are maintained including, decreased sedimentation rates, improved distribution of dissolved oxygen, wetland management capability, and improved migratory bird habitats.

Determine best alternatives to expand bathymetric diversity and restore deep water habitats. Complete projects at select sites to provide distributed critical habitat units. .

Elk River Complex:

Monitor habitat, flows and bathymetry at this productive site, which is presumed to be the best example of natural river habitats in Pool 13. If habitat conditions deteriorate, initiate projects to protect and enhance the site, with emphasis on maintenance of natural river processes.

Gomer's Lake:

Restore depth for fish species by dredging into and within Gomer’s Lake.

Improve aquatic vegetation communities with construction of a berm designed to divert sediment laden flows and buffer wind fetch.

Increase extent and quality of terrestrial habitats with appropriate forest and prairie plantings on diversion berm.

Potters Marsh

Monitor features of the completed HREP and insure that project objectives are maintained. Objectives include deep water habitat for over-wintering fish, a sediment trap function, wetland development, and isolated wetland pools.

Lower Pool 13:

Investigate feasibility of improving fish passage through Dam 13 into Pool 14.

Improve opportunity for the establishment of aquatic vegetation by constructing islands to buffer wind generated waves.

Construct islands to provide terrestrial habitat for turtles and nesting migratory birds and for other wildlife values. Dredged material from channel maintenance activities could be utilized to construct the islands.

Pool 13 Entire:

Complete bank stabilization or flow modifications at sites where rapid bank line erosion threatens side channel or backwater diversity. The project should begin with a pool-wide inventory.

Review Pool 13 water management and determine feasibility, impacts and anticipated results of potential changes in water management, especially the partial restoration of seasonal low water elevations.

Inventory and assess mussel populations throughout the pool and design appropriate habitat management.

Pool 13 Watershed:

Complete an interagency review of water quality information from Pool 13 tributaries, including anticipated or known pool impacts and opportunities to mitigate any resource problems.

Initiate, support or participate in cooperative watershed management efforts including the Maquoketa River Alliance and the Elk River watershed initiative.

Advocate for implementation of the Wetland Reserve Program or similar programs on tributary floodplains, especially the Maquoketa River.

Upper Mississippi River System:

Develop pool-wide environmental planning aids, including hydraulic models, topographic and bathymetric surveys, substrate maps and other information needed to facilitate engineered solutions for habitat diversity.

Design, construct and test structures to maintain or restore desired habitat features.

Expected or Desired Results:

1. A combination of engineered solutions, applied to select sites, will aid in the restoration and maintenance of important habitat features of side channels and backwaters impacted by accelerated sedimentation. Sediment accumulation attributed to the navigation project can be reduced at project sites to maintain or restore important habitat values. Aquatic values and the life span of targeted backwaters will be extended. Fish over-wintering habitats will be maintained within five-mile intervals. Side channels targeted for improved management of coarse sediments may be maintained indefinitely. Main channel training structures, however, will preclude much potential for large-scale regeneration of aquatic habitats, and the long-term trend to a less diverse system will continue.

2. Habitats critical to migratory birds, especially aquatic food resources and forests, will be extended and improved if the problems of suspended sediments and sustained high water elevations can be mitigated. Water management alternatives, even in small scale, promise important, periodic rejuvenation of aquatic vegetation.

3. Expected or desired results relating to problems associated with the accumulation of coarse sediments are included in number 1, above.

4. Diverse forest communities can be developed on sites significantly elevated above the water table or they can be maintained on higher areas of the floodplain with careful management and intensive regeneration efforts. Sediment accumulation will slowly improve the woodland site index at some locations. There may be opportunities for forest restoration on lands currently in agricultural production within levee and drainage districts. Forest stand improvement goals will be established throughout the Pool.

5. Long-term improvement in watershed management and best management practices are expected to reduce sediment loads from immediate watersheds and the basin. River managers must ensure that river impacts are a measured cost of upland erosion and that Mississippi River natural resource and water quality issues are represented in planning and implementation of agricultural, urban and industrial watershed management. Programs which benefit restoration of tributary floodplains as the Wetland Reserve Program, Conservation Reserve Program or Emergency Wetland Program will be identified and supported. However, improving soil and water management on private lands throughout the basin is a complicated task and a decades old effort that will not soon be resolved. Accelerated sediment delivery will remain a problem.

6. The installation of fish passage structures or amended lock and dam operation can improve opportunity for fish movement between pools.

Last updated: May 12, 2009