During August 2001, the Geneva Lake Environmental Agency conducted an aquatic plant survey to assess the condition of the submerged aquatic plant community. This plant survey was conducted as a part of the Geneva Lake Aquatic Plant Management Plan that the Agency is preparing as a part of the larger overall Geneva Lake Management Plan.
Some preliminary findings of the plant survey were interesting. Twenty-seven transects were used with each transect divided into five depth classes and a random depth within each class sampled. Twenty-three species representing 11 genera were identified. Two new species were found in this survey. Perhaps the most interesting finding of the survey was the significant increase in the aquatic plant called widgeon grass or nut grass, Ruppia currhhosa. This is a long stringy type plant with leaves that look very similar to its stem. Cut parts of this plant have been found floating in large mats in the middle of the lake and washed up on the shores.
It was by far the most abundant plant encountered in this survey. Although it was identified as being in the lake during the last aquatic plant survey in 1994, it was not found at the present densities.
Watch the Agency's web page for a more complete discussion on the aquatic plant survey and aquatic plant management plan. A complete report and a less technical summary are available at the Agency's office.
Another product of the aquatic plant survey was the preparation of an aquatic plant management plan (see map of recommended management below). In general the lake was divided into three separate aquatic plant management areas. The “No Restriction Zone” where it is recommended that there be no restriction on the aquatic plant management strategies if they are compatible with State requirements. The “Native Zone” are areas that have a diverse and healthy plant community and thus no management is needed or recommended unless conditions change. The “Watch Zone” is the largest area in size and includes areas were the plant community may need some minor management but for the most part is relatively stable. An overlay “Riparian Zone” can be located in any one of the other three zones but is restricted to only a 30 ft. wide strip running perpendicular to the shore and extends out into deeper water. This zone is to allow for riparian management of aquatic plants in their swim, mooring or pier areas.
Aquatic Plants Found in Geneva Lake from Various Inventories, Geneva Lake, Walworth County WI
Source: GLEA
| Plant Species | Common Name | Found in | |||
|---|---|---|---|---|---|
| 1976 | 1994 | 2001 | 2009 | ||
| Ceratophyllum demersum (L.) | Coontail | x | x | x | x |
| Chara* spp. | Muskgrass | x | x | x | x |
| Elocharis spp. | Rush | ||||
| Elodea canadensis (Michx.) | Common waterweed | x | x 1 | x | |
| Elodea nutallii (Planchon.) | Slender waterweed | x | x | ||
| Heteranthera dubia (Jacq.) Zosterella dubia | Water stargrass | x | x | ||
| Myriophyllum exalbensence (Fern.) | Northern water milfoil | x | x | x 1 | x |
| Myriophyllum heterophyllum (Michx.) | Variable milfoil | x | |||
| Myriophyllum spicatum** (L.) | Eurasian water milfoil | x | x | x | x |
| Najas flexilis (Willd.) | Naiad | x | x | x | |
| Najas gacillima (A.Braun) | Pondweed | x | |||
| Najas marina (L.) | Spiny pondweed | x | |||
| Potamogeton amplifolius (Tuckerman) | Large leaf pondweed | x | x | x | x |
| Potamogeton crispus** (L.) | Curly leaf pondweed | x | x | x | x |
| Potamogeton diversifolius (Raf.) | Waterthread pondweed | x | |||
| Potamogeton fresii (Rupr.) | FrieÕs pondweed | x | x | ||
| Potamogeton foliosus (Raf.) | Leafy pondweed | x | x | ||
| Potamogeton gramineus (L.) | Variable pondweed | x | x | ||
| Potamogeton illinoensis (Morong.) | Illinois pondweed | x | x | x | |
| Potamogeton nodosus (Poiret.) | River pondweed | x | x | x | x |
| Potamogeton natans (L.) | Floating leaf pondweed | x | x | x | x |
| Potamogeton pectinatus (L.) | Sago pondweed | x | x | x | x |
| Potamogeton praelongus (Wulfen) | White stem pondweed | x | x | x | |
| Potomogeton pusillus | Small pondweed | x | |||
| Potamogeton richarsonii (Ar. Bennett) | Richardsons pondweed | x | x | ||
| Potamogeton robinsii (Dakes) | Fern pondweed | x | |||
| Potamogeton zosteriformis (Fern.) | Narrow leaf pondweed | x | x | x | x |
| Ranunculus longirostris (Godron) | Water buttercup | x | x | x | |
| Ruppia spp. | Wigeon grass | x | x | ||
| Utricularia geminiscapa (Benj.) | Hidden flower bladderwort | x | |||
| Utricularia vulgaris (L.) | Bladderwort | x | x | x | x |
| Vallisneria americana (L.) | Water celery | x | x | x | x |
| * an algae, not a macrophyte | 1 recorded as genus only | ||||
| ** exotic species | |||||