Upper Midwest Environmental Sciences Center

Click on the image for a larger view of Pool 4

Navigation Pool 4 is 73.3 km (44 river miles) long and includes 14,700 ha (36,300 acres) of aquatic habitat. It is located between Lock and Dam 3 (above Red Wing, Minnesota) and Lock and Dam 4 (Alma, Wisconsin). Major tributaries include the Cannon and Vermillion Rivers on the Minnesota side and the much larger Chippewa River on the Wisconsin side. Lake Pepin, a riverine lake created by the Chippewa River delta, is located in the middle of Pool 4. The location of Lake Pepin divides the rest of the pool into upper Pool 4 and lower Pool 4. The smaller backwaters of upper Pool 4 have been degraded by sedimentation, whereas the larger backwaters of lower Pool 4 are much better habitat for vegetation.

Click on the image for a larger view of Pool 5

Navigation Pool 5 is 23.5 km (14.6 river miles) long and includes 4,500 ha (11,120 acres) of aquatic habitat. It is located between Lock and Dam 4 (Alma, Wisconsin) to the north and Lock and Dam 5 (south of Minneiska, Minnesota) to the south. Major tributaries include the Zumbro and Whitewater Rivers, both of which enter on the Minnesota side. The upper section of Pool 5 has small backwater sloughs connected to the main channel. The middle section contains high bank islands adjacent to the main channel, along with deep secondary channels, numerous braided tertiary channels and small backwater sloughs. The lower section primarily contains two large open expanses of water divided by a narrow band of islands that separate Weaver Bottoms from Spring Lake and the rest of the impounded area.

Click on the image for a larger view of Pool 7

Navigation Pool 7 is 19.6 km (12 river miles) in length and is bounded by Lock and Dam 6 (Trempealeau, Wisconsin) to the north and Lock and Dam 7 (Dresbach, Minnesota) to the south. It encompasses 5,400 ha (13,300 acres) of aquatic habitat. Pool 7 contains braided channels and sloughs in the upper section and a large open lake-like area (Lake Onalaska) in the lower section of the pool. The Black River on the Wisconsin side is a major tributary.

Click on the image for a larger view of Pool 8

Navigation Pool 8 is 38.8 km (23.3 river miles) long and is bounded by Lock and Dam 7 (Dresbach, Minnesota) to the north and Lock and Dam 8 (Genoa, Wisconsin) to the south. It encompasses 9,000 ha (22,100 acres) of aquatic habitat. Major tributaries include the Black, Root, and La Crosse Rivers. The upper section of Pool 8 has high bank islands adjacent to the main channel, deep secondary channels, and backwater sloughs. The middle section contains low islands, braided channels, and small backwater sloughs. The lower section is a large open expanse of water.

Click on the image for a larger view of Pool 12

Navigation Pool 12 is 42.1 km (26.3 river miles) in length and is bounded by Lock and Dam 11 (Dubuque, Iowa) to the north and Lock and Dam 12 (Bellevue, Iowa) to the south. It encompasses 4,879 ha (12,057 acres) of aquatic habitat. Levees are limited to the urban and industrial complex near Dubuque. There are no major tributaries entering the pool. Smaller streams include Catfish Creek (Iowa) and the Menominee, Sinsinawa, and Galena Rivers (Illinois). A distinguishing character of Pool 12 is that islands are interspersed throughout the pool. There is no large expanse of open water typical of many pools.

Click on the image for a larger view of Pool 13

Navigation Pool 13 is 52.1 km (34.2 river miles) in length and is bounded by Lock and Dam 12 (Bellevue, Iowa) to the north and Lock and Dam 13 (Fulton, Illinois) to the south. It encompasses 11,400 ha (28,100 acres) of aquatic habitat. Similar to pools upstream, Pool 13 contains many high bank islands adjacent to the main channel in the upper section, braided backwater channels and sloughs in the middle section, and a large open lake-like area in the lower section of the pool. Major tributaries include the Apple and Plum Rivers on the Illinois side and Maquoketa and Elk Rivers on the Iowa side.

Click on the image for a larger view of Pool 26

The Navigation Pool 26 study area includes water bodies along the Upper Mississippi River from Lock and Dam 25 (Winfield, Missouri) to Lock and Dam 26 (Alton, Illinois) and the lower Illinois River from its confluence with the Mississippi River north to Illinois River mile 12. This reach of the two rivers is bordered by high bluffs on the Illinois side and low elevation floodplain on the Missouri side. The reach encompasses 9,500 ha (23,700 acres) of aquatic habitat. Presently, most of the backwaters of the lower Illinois River are isolated from the river by low levees so as to decrease sedimentation and allow management for waterfowl. Likewise, many of the secondary channels of the Mississippi River are isolated from the river on the upstream side to create backwaters and to reduce sedimentation.

Click on the image for a larger view of Alton Pool

Alton Pool on the Illinois River includes water bodies along the lower Illinois from the La Grange Lock and Dam at river mile 81 near Beardstown to its confluence with the Mississippi River at river mile 0 (Grafton, Illinois). The reach encompasses 6,500 ha (16,100 acres) of aquatic habitat. Major tributaries include Mc Gee, Maucoupin, and Otter Creeks. Presently, most backwaters of the lower Illinois River are isolated from the river by low levees to decrease sedimentation and allow management for waterfowl. Alton Pool houses several large contiguous backwater lakes including Meredosia and Swan Lakes, but these backwaters are degraded by excessive sedimentation.

Click on the image for a larger view of La Grange Pool

La Grange Pool on the Illinois River is about 130 km (80 river miles) long and encompasses 10,750 ha (26,500 acres) of aquatic habitat. It is bounded by Peoria Lock and Dam to the north and La Grange Lock and Dam to the south. This reach has the highest proportion of backwaters, except for Pool 4, but these backwaters are highly degraded by excessive sedimentation over the last 150 years. Many backwaters are isolated by low levees to enhance waterfowl habitat management. Major tributaries include the Sangmon, Mackinaw, and LaMoine Rivers.