Rock Island Ecological Services Office
Midwest Region



Description of Pool 12:

Pool 12 is the 26.3 mile segment of the Mississippi River extending upstream from Lock and Dam 12 at Bellevue, Iowa to Lock and Dam 11 at Dubuque, Iowa. Bordered by the states of Iowa, Illinois and Wisconsin, Pool 12 includes ____ acres of public lands and waters. Although the project area is Pool 12, planning considerations extend to areas which impact pool resources, including watersheds, natural floodplains behind levees, and private lands within the pool.

Pool 12 encompasses most of the natural floodplain, as levees are limited to the urban and industrial complex near Dubuque. Although Dubuque area development dominates the upper pool, the riparian environment downstream to Bellevue is rural. There are no major tributaries entering the pool. Smaller streams include Catfish Creek (Iowa) and the Menominee, Sinsinawa and Galena Rivers (Wisconsin). The total watershed of tributaries entering the Pool is 800 square miles.

A distinguishing character of Pool 12 is that islands are interspersed throughout the pool. There is not as large as an expanse of open water typical of many pools. Sedimentation and suspended sediments are a serious problem, and impacts are especially obvious in the lower pool area below the Galena River. Vegetation throughout the pool is generally very sparse, although emergent aquatic plants are pioneering accreted areas in the lower pool. Much deep water habitat in backwaters is gone.

Public lands and waters within Pool 12 include the Upper Mississippi River National Wildlife and Fish Refuge, General Plan Lands of the Nine-Foot Navigation Project, and lands and waters owned by the States of Iowa, Wisconsin and Illinois.

Resource Problems and Issues:

Fine sediments are accumulating at accelerated rates within backwaters and other floodplain locations. These rates are 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. An elevated water table favors moisture tolerant forest species, limits site potential for species diversity, and promotes plant succession to moisture tolerant grasses.

5. Watershed discharges into Pool 12 contribute to significant water quality and habitat problems which impact natural resources. Issues and examples include accelerated sedimentation with associated nutrient and contaminate delivery. More information is needed about discharges and impacts within Pool 12.

6. Locks and dams 12 and 11 restrain fish passage between pools.

7. Information is needed to better assess and manage Pool 12 mussel populations.

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

Resource Opportunities:

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 with features designed to (a) scour sediment from select sites, (b) maintain sediments in suspension to prevent accumulation at select sites or (c) direct sediment laden flows away from select sites. 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, and (c) actions within watersheds and the pool to lower turbidity and sedimentation rates. 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 12 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 extrapolate ie: clear cutting or rpm plantings, is that what we mean., (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 at lower tributary sites including reduced bank erosion of coarse sediments and (c) initiation of needed monitoring if information is not available.

6. Structures or modification at Locks and Dams 11 and 12 can improve fish passage (Resource Problem 6). Opportunities include the design and construction of ladders facilitating fish passage at all seasons.

7. A mussel inventory is needed to provide basic information on Pool 12 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 12 may be located on the Desired Future Habitat Conditions maps which follow this section.

Upper Pool 12:

Modify Dam 11 to introduce flow to isolated aquatic areas in Pool 12.

Restore depth for fish species by dredging into and within White City/Stump Island backwater.

Fentress Lake / Lake Lacoma:

Restore depth to alleviate winter oxygen depletion.

Nine Mile Island:

Restore shallow aquatic habitat in the upper reaches of rapidly accreting wetlands. Consider pothole blasting technique.

Restore over-wintering habitat for centrarchids with dredging.

Increase island elevation with dredged material to introduce and sustain mixed bottomland tree species.

Mid Pool 12:

Complete a proposed Habitat Rehabilitation and Enhancement Project (HREP) to restore dispersed over-wintering habitat for centrarchids in a ten mile reach of the pool. Sites include Keyhoe Slough and Stone, Tippy, Hires, No Name, Fish Trap and Sunfish Lakes.

Improve island site index for mixed bottomland tree species by raising ground elevation with dredged material from over-wintering habitat project.

Reduce accelerated sediment accumulation in Sunfish Lake by diverting Galena River flows with a low, deflection berm.

Deflect high channel flows from Keyhoe Slough and Fish Trap Lake with a low berm simulating a natural levee

Wise Lake:

Monitor habitat, flows and bathymetry at this productive site, which is presumed to be the best example of natural river habitats in Pool 12. If habitat conditions deteriorate, initiate projects to protect and enhance the site, with emphasis on maintenance of natural river processes.

Bellevue Slough:

Improve island site index for mixed bottomland hardwoods and plant select tree species. Utilize dredged material from channel maintenance and fine sediments to raise ground elevation and site index.

Lower Pool 12:

Investigate feasibility of fish passage structure to facilitate fish movement through Dam 12 into Pool 12.

Utilize an inventory of existing habitat, flows and bathymetry to define a long-term habitat budget to be maintained with appropriate management. Characters may include ratios and interspersion index of cover types, bathymetry and flows.

Construct a barrier island to buffer wind generated waves.

Improve island site index for mixed bottomland hardwoods and plant select tree species. Utilize dredged material from channel maintenance and fine sediments to raise ground elevation and site index.

Pool 12 Entire:

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

Review Pool 12 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 12 Watershed:

Complete an interagency review of water quality information and authorities from Pool 12 tributaries, including anticipated or known pool impacts and opportunities to mitigate any resource problems. Initiate or support watershed management efforts.

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:

A combination of engineered solutions will aid in the restoration and maintenance of important habitat features of side channels and backwaters at select sites. 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 improved and extended 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 sediment problems within side channels are included in number 1, above.

4. Naturally sustained diverse forest communities in Pool 12 can be developed on sites raised significantly above the water table and maintained on higher areas of the floodplain edge. Careful management and intensive regeneration efforts will maintain desirable communities on some existing sites. Sediment accumulation will slowly improve the woodland site index at some locations. There will 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 is expected to reduce sediment loads from 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 watershed management. Programs which benefit restoration of tributary floodplains such as the Wetland Reserve Program, Conservation Reserve Program or Emergency Wetland Program will be identified and supported.

6. The installation of fish passage structures at locks and dams 11 and 12 will reduce restrictions to fish movements and restore seasonal fish movement to a wider cross-section of the dam location.

7. Additional information is needed to manage envir

Back to FWIC Upper Mississippi River Pool Plans


Last updated: May 12, 2009