draft 10/21/02, incorporating J Lindell’s edits.
MISSISSIPPI RIVER - POOL 11 ENVIRONMENTAL PLAN
DESIRED FUTURE HABITAT CONDITIONS
Description of Pool 11:
Pool 11 is the 32.1 mile segment of the Mississippi River extending upstream from Lock and Dam 11 at Dubuque, Iowa to Lock and Dam 10 at Guttenberg, Iowa. Bordered by the states of Iowa and Wisconsin, Pool 11 includes 29,270 acres of public lands and waters. Although the project area is Pool 11, planning consideration will extend to areas which impact pool resources including watersheds and private lands within the floodplain.
The landward boundaries of Pool 11 encompass most of the natural floodplain. Throughout the pool, the Mississippi River valley is confined to a narrow bedrock gorge which is a dominate feature of geomorphic reach 4. The interface between the river floodplain and bluffs is abrupt.
Major tributaries to the Mississippi River within Pool 11 are the Turkey River and Little Maquoketa River (Iowa) and the Grant River and Platte River (Wisconsin). Land use within tributary watersheds is predominantly agricultural. These tributaries deliver significant quantities of suspended sediment to the pool from their combined watershed of 2,230 square miles. Urban and industrial sites include Guttenberg and Cassville in the upper pool and Dubuque in the extreme lower pool area.
Typical of most navigation pools in geomorphic reach 1-4, the water to land ratio changes dramatically within the pool. Islands, channels, and smaller backwaters of the upper pool open to larger backwaters at mid-pool and the lower pool is a broad expanse of open water.
Public lands and waters within Pool 11 include the Upper Mississippi River Wildlife and Fish Refuge, General Plan Lands of the Nine-Foot Navigation Project, and lands and waters owned by the States of Iowa and Wisconsin.
Resource Problems and Issues:
1. Sediments are accumulating at accelerated rates within backwaters and the range and ratios of bathymetric diversity is declining. Suspended sediments and sedimentation limit the potential for aquatic vegetation. Diversity and quality of aquatic habitats have declined.
2. Coarse sediments accumulate in side channels where they fill valuable habitats and restrict flows. Sediments from channel maintenance dredged material disposal have restricted side channels.Island erosion introduces undesirable flow characters into some backwaters and side channels and can remove protection for aquatic areas.
4. Elevated surface water levels and high soil moisture restricts the potential for forest regeneration and forest diversity. Site conditions may favor succession to grasses, particularly Reed canary grass.
5. Specific fish and wildlife habitat concerns include: low productivity of benthic invertebrates, vegetation and fish in lower Pool 11, the loss or degradation of backwater and side channel habitats including fish over-wintering sites, and insufficient production of food resources for migratory waterbirds.
6. Locks and dams 10 and 11 restrain fish passage between pools.
7. The current water management regime, especially the avoidance of seasonal low water, removes much potential for periodic regeneration of aquatic habitats.
1. Restoring the full range of bottom contour and depth (bathymetric diversity) within backwaters and reducing sediment delivery and re-suspension 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. Re-suspension of sediments within the Pool can be reduced by interrupting the energy of current, wind and wave with islands, structures, or vegetation.
Sediment delivery problems can be best resolved at the watershed scale with best management practices designed to limit soil loss throughout the watershed. Opportunities to improve watershed impacts can include (a) collaborative efforts to reduce upland soil erosion, (b) reducing lower tributary problems including bank erosion of coarse sediments, and (c) targeting important tributary watersheds and floodplain within programs as the Emergency Wetland Program, Conservation and Wetland Reserve Programs.
2. 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 2. Opportunities to maintain existing or improve degraded side channels 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 11 to aid analysis and project design. Dredging can also restore side channel productivity and it is especially appropriate when used in combination with techniques which sustain the desired condition. Careful and coordinated management of Navigation Project maintenance dredging and dredged material disposal can avoid most negative impacts.Protecting critical shorelines from erosion will address Resource Problem 3. Opportunities include a variety of (a) stabilization techniques including armoring banklines, raising island elevations at key sites, off-shore revetments, current deflection, and vegetation management, or (b) eroded island may be restored with fill material, or encouraged to accrete.
4. Mitigating the long-term impacts of an elevated water table can help improve forest regeneration and species diversity at select sites (Resource Problem 4). Opportunities include (a) raising ground surface elevation, (b) use of intensive regeneration aids including planting and competition control, (c) careful management of existing diverse stands, and floodplain edge sites, (d) experimental plots testing a variety of forest management techniques, (e) examination of pool water management profiles and topography to identify sites with best potential for diverse forest management , (f) island construction and (g) conversion of appropriate sites to native grasses and forbs.
5. There are appropriate opportunities to address all issues identified in Resource Problem 5. Opportunities include restoring the potential for diverse habitats at select sites with (a) island protection, accretion and construction, (b) structures designed to modify flows for environmental objectives, (c) amended water management, (d) restoration of bathymetric diversity in backwater habitats, and (e) restoration of moist soil communities and mud and sand bar habitats.
6. Appropriate modifications to Locks and Dams 10 and 11 or their operations can improve fish passage (Resource Problem 6). Opportunities include the design and construction of ladders or amending lock or dam operation.
7. Timely water level fluctuation, planned within the constraints of the navigation system, can induce biological responses which rejuvenate aquatic habitats (Resource Problem 7). Opportunities include periodic reduced summer water elevations designed to mimic natural summer low flow events.
To facilitate planning and illustration, proposed actions are organized within geographical units. Geographical unit boundaries and the locations of actions proposed within Pool 11 may be located on the Desired Future Habitat Conditions maps which follow this section.
Swift Slough, Dead Slough and Guttenberg Waterfowl Ponds:
- Restore water control capabilities within Big Pond to facilitate production of food resources for migratory waterbirds.
- Work with St. Paul District and other appropriate authorities to investigate potential to extend periods when fish may pass through Dam 10.
Restore conditions which maintained historic centrarchid over-wintering sites in Swift Slough, including less current and sediment introduction and increased water depths.
Monitor the extent of wetland vegetation classes, set action levels for management response, and initiate appropriate management to maintain vegetation at desired coverage. Maintain emergent and submersed vegetation at the l989 coverage or higher. Maintain moist soil and wet meadow communities at 200% of l989 coverage.
Improve island site index for mixed bottomland tree species at select sites by raising ground elevations, perhaps using existing channel maintenance disposal site material.
Identify, restore or stabilize island erosion or ‘breaks’ on Island 189, which introduce undesirable main channel flows into backwaters, or at sites where that condition is imminent.
Determine best methods to restore substrate diversity in Cassville Slough and bathymetric diversity in both Cassville Slough and associated backwaters.
Maintain aquatic vegetation at 1989 coverage or higher, with a program of monitoring, setting of action levels and appropriate management.
Goetz Slough, St. Louis Woodyard:
Restore full range of bathymetric diversity in Goetz Slough by deepening select areas with best restoration techniques.
Maintain existing habitat quality within St. Louis Woodyard and Bluff Slough complex with techniques including inventory, assessment of problems and identification of remedial measures.
Identify sites of island erosion which threaten side channel and backwater habitats and implement appropriate restoration and stabalization of eroded sites.
Convert historic dredged material disposal sites to prairie or forest communities.
Turkey River Bottoms:
Convert agricultural land to floodplain moist soil, wet meadow, and forest habitats and ensure their temporal availability to migratory birds. Utilize appropriate water and vegetation management techniques.
Evaluate best methods to restore bathymetric diversity in Spring, Wachendorf and Woodduck Lakes and to protect areas from accelerated sedimentation in the future.
Identify sites to restore forest communities, especially those on higher elevations, and complete forest restoration.
Jack Oak Island:
Identify sites of island erosion which threaten side channel and backwater habitats and implement appropriate restoration and stabilization of eroded sites.
Evaluate flow characters to determine structural opportunities to maintain select habitat characters at no net loss, or to improve habitat qualities. Habitat issues of special concern include maintenance of deep water within backwaters and maintaining channel habitat diversity.
Utilize all appropriate forest management techniques to maintain species diversity within existing mixed stands.
Bertom and McCartney Lakes:
Construct an island in McCartney Lake to shelter and encourage aquatic vegetation and to moderate sediment re-suspension. This action will complement the previous Habitat Rehabilitation and Enhancement Project (HREP).
Provide water level management capability on an isolated wetland at upper end of Haybottoms complex to sustain wetland habitat quality and ensure seasonal habitat for migratory waterbirds.
Identify erosion sites on main channel border islands which threaten side channel and backwater habitats and implement appropriate restoration and stabilization.
Restore fish over-wintering habitat and improve forest diversity with a combined project linking backwater dredging with increased island elevations and tree planting.
Restore diverse forest community within abandoned farm fields in the Dago Slough area.
Maintain existing habitat quality within Bunker Chute and island complex. Establish an inventory and monitoring protocol for select habitat characters, including side channel bathymetry and island extent.
Synder Slough and Hurricane Chute:
Islands will be restored or protected from erosion at select sites to diversify water velocities and flows, reduce rates of sediment accumulation and re-suspension, improve bathymetric diversity and vegetation, and maintain terrestrial habitats.
Fish over-wintering habitats will be identified and monitored as the first step to ensure availability of this habitat within the complex.
Increase emergent vegetation to 120% of l989 coverage.
Grant River Delta:
Restore islands to diversify water velocities and flows, reduce sediment re-suspension, improve bathymetric diversity, and to increase extent and diversity of terrestrial habitat.
Fish over-wintering habitats will be identified and monitored as the first step to ensure availability of this habitat within the complex. This habitat will be created if the river substrate is used to restore islands.
Increase emergent vegetation to 200% of l989 coverage.
Pool 11 Islands:
Complete the habitat features and goals identified in the Pool 11 Islands HREP planning process, including: restore and maintain quality waterbird migration habitat, provide quality waterbird summer resident habitat, create habitat for other migratory and resident vertebrates, enhance or construct off-channel laucustrine fisheries habitat, and enhance and maintain habitat for riverine fish species and mussels.
Mud Lake and John Deere:
Complete habitat features and goals identified in the Pool 11 Islands HREP planning process, as in Pool 11 Islands above.
Increase emergent vegetation to 160% of existing coverage.
Sinnippee Creek and Sunfish Lake
Complete habitat features and goals identified in the Pool 11 Islands HREP planning process, as in Pool 11 Islands above.
Investigate feasibility of fish passage structure, or modifications to dam operations, to facilitate fish movement through Dam 11and into Pool 11.
Pool 11 Entire:
An inventory and monitoring protocol for priority areas and select terrestrial and aquatic habitat characters will be designed and completed. The inventory results will be used to establish a minimum management action level for the selected characters.
Restore backwater over-wintering habitat within 3 mile intervals at site locations described above.
Inventory priority sites and determine best opportunities to maintain or improve channel habitats, with special emphasis on development of quality mussel habitat.
Improve vegetation diversity on elevated dredge spoil placement sites by planting to appropriate trees, grasses and forbs.
Review Pool 11 water management and determine feasibility, impacts and anticipated results of potential changes in water management, especially the partial restoration of seasonal low water elevations.
Pool 11 Watershed:
Biologists will participate in the Turkey River Alliance, Little Maquoketa River watershed, and the Grant and Platte River Priority Watershed programs to advocate for river resources. A special effort will be made to identify opportunities to work with other groups on watershed issues important to river resources.
Advocate for select watersheds and tributary floodplains to be priority areas for programs including the Wetland Reserve Program, Conservation Reserve Program, or State initiatives.
Facilitate floodplain protection opportunities which may become available, such as the Emergency Wetland Program.
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:
Engineered solutions can reduce rates of sediment accumulation and sediment re-suspension at select backwaters and extend or restore diverse habitat values within key units interspersed within the Pool. Fish over-wintering habitats will be maintained within three mile intervals. Dam operation and channel training, however, will perpetuate conditions which both accelerate net accumulation of sediment and limit the formation of backwaters.
Long-term improvement in watershed management is expected to reduce basin sediment loads. 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 development and implementation of watershed management. Opportunities to promote best management practices on small watersheds impacting discreet river habitat units, or special programs targeting larger watersheds, will be actively pursued by local managers. 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 management on private lands throughout the basin is a complicated task and decades old effort that will not soon be resolved. Accelerated sediment delivery will remain a problem.
A combination of engineered solutions will aid in the restoration and maintenance of side channels and important habitat features at select site. Side channels selected for improved management of coarse sediments may be maintained indefinitely. Main channel flow regulation, however, may preclude potential for large-scale regeneration of aquatic habitats and perpetuate the long-term trend to a less diverse system.
Island erosion which threatens side channel or backwater resources will be identified and stabilized. Preemptive action will save resources and expense. Island restoration or creation will be a useful tool to maintain or restore River characters and habitats.
Diverse forest communities can be restored on small areas where ground elevations will be raised, on constructed islands, and at Turkey River Bottoms. Intensive forest management can buffer some impacts of sustained high water at select sites. Sediment accumulation may slowly improve the woodland site index at some locations. River managers will support forest restoration alternatives on private land floodplain areas of the River and immediate tributaries. Although these actions will retain important forest habitat components, most forest sites with the Pool will become less diverse and many may eventually change to other cover types.
Specific fish and wildlife habitat concerns will be addressed with a variety of projects. HREP projects in lower Pool 11 will be completed. Other projects, designed to maintain, restore or improve side channel and backwater habitats can be completed at select sites where results are most effective. These projects are expected to ensure core units of critical habitat, but are presumed as minimum habitat objectives to meet present and future requirements for migratory waterbirds and other migratory and resident wildlife.
- The installation of fish passage structures, or amended dam operation, at locks and dams will reduce restraints to fish movements and restore seasonal fish movement to a wider cross-section of the dam location.