1993

1994

1995

1996

1997

1998

1999

2000

number of sites sampled

122

110

118

118

116

132

123

135

all submersed vegetation

71.3

100.0

99.2

98.3

94.8

85.6

95.1

90.4

coontail

60.7

100.0

99.2

97.5

93.1

81.1

94.3

86.7

Canadian waterweed

Elodea canadensis

5.7

25.5

2.5

0.8

0.9

3.8

1.6

3.7

nodding waternymph

Najas flexilis

1.6

12.7

16.9

13.6

20.7

17.4

14.6

19.3

curly pondweed

Potamogeton crispus

0.8

30.0

16.1

37.3

7.8

3.0

0.8

5.2

leafy/small pondweed

P. foliosus/P. pusillus

0.8

31.8

40.7

80.5

51.1

29.5

20.3

67.4

sago pondweed

P. pectinatus

20.5

10.0

16.1

10.2

14.7

15.9

19.9

26.7

flatstem pondweed

P. zosteriformis

-

-

-

0.8

-

0.8

2.4

-

common bladderwort

Utricularia macrorhiza

25.4

0.9

9.3

11.9

4.3

35.6

21.1

25.2

all rooted floating leaf vegetation

82.8

81.8

86.4

92.4

93.1

93.9

98.4

94.8

American lotus

Nelumbo lutea

-

1.8

-

1.7

3.4

4.5

6.5

3.0

yellow pond-lily

Nuphar variegata

0.8

2.7

3.4

1.7

1.7

0.8

1.6

3.0

white water-lily

Nymphaea odorata

82.8

80.9

86.4

91.5

90.5

90.2

92.7

92.6

Total number of species recorded

9

10

9

11

10

11

11

10