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2002 Results in Pool 7 of the Upper Mississippi River

Sampling Effort

Sampling in Pool 7 began on August 5 and ended on August 28, 2002. Of the 406 sites targeted for sampling at the beginning of the season, 392 were sampled (Figure 5).

Submersed Aquatic Vegetation

Submersed aquatic vegetation (SAV) covered about 39% of the shallow water areas poolwide and was found throughout most of the pool (Table 4; Figure 6). Contiguous backwaters had the highest percent frequency of SAV (90%). Impounded areas (60%), secondary channels (25%), and main channel border (7%) followed in decreasing order.

A total of 15 species were recorded in the entire pool. Contiguous backwaters and impounded areas had the most species recorded (14) followed by secondary channels (8), and main channel border areas (4).

Coontail (29%) was the most frequently recorded species in Pool 7 followed by Canadian waterweed (27%) and wildcelery (22%). Coontail (86%) and Canadian waterweed (77%) dominated contiguous backwaters. In impounded areas, wildcelery (54%) was the dominate species. Canadian waterweed (19%) was most frequently encountered in secondary channels, while wildcelery (6%) and water stargrass (4%) were dominant in main channel border areas.

Rooted Floating-Leaf Vegetation

White waterlily, American lotus, and yellow pond-lily were the three rooted floating-leaf species recorded. The three species together covered about 4% of the shallow water areas and appeared to be limited to more sheltered areas of Pool 7.

The percent cover of rooted floating-leaf species was the highest in contiguous backwaters (9%) followed by secondary channels (6%) and impounded areas (3%). No rooted floating-leaf vegetation was found in main channel border areas.

White waterlily and American lotus were scattered throughout much of Pool 7, while yellow pond-lily was found at one site in the north end of Lake Onalaska.

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