Maple Lake Association

Weed Control and Water Quality Issues

Lakeshore Environmental, Inc. May, 2010

OVERALL ASSESSMENT OF MAPLE LAKE

6.1 Maple Lake Key Watershed Findings

Based on the laboratory analyses (sediment and water),the watershed around Maple Lake has been impacted nutrient and pollutant loads from surrounding rivers and tributaries as well as nutrient and sediment loads from residential development around the lake shoreline. In addition, the lake has been impeded by M. spicatum fragments from recreational boats and thus an aggressive approach to the control of M, spicatum on Maple Lake or a preventative measure for the spread of M. spicatum fragments is highly recommended. The highly developed shoreline around Maple Lake emphasizes the need for riparians to follow sound land use management practices to protect the water quality of the lake. The low quantity of riparian vegetation at some shoreline areas allows for greater opportunities for nutrient and sediment (erosion) inputs from the land to the lake. Although there is still a fair abundance of forested lands in the extended watershed, the majority of the wetlands have been altered and thus nutrient filtering capacities have been dramatically reduced. As a result, it is critical that the riparians and residents around Maple Lake adopt sound watershed management strategies to improve and protect the water quality of the lake. The remaining forest land and wetlands should be preserved to the extent possible.

6.1.1 Maple Lake Soils and Land Use Implications

A few shoreline areas around Maple Lake contain soils that may compromise the water quality of the lake. The Morocco Loamy Sands located at the south shore and on Maple Island are poorly drained, and may experience saturation during periods of increased precipitation. Such increased saturation may cause bacteria (from waterfowl feces) or nutrients (from lawn fertilizers) to directly enter into the lake. The sands are substrates that are well-drained and are not likely to encounter ponding or saturation, yet many sites contain slopes that are prone to erodibility. Since not much can be done to change the properties of the soils surrounding the lake, it is recommended that waterfowl droppings be reduced by goose control methods (especially nest destruction as permitted) and soil erosion control methods. Such techniques will dramatically decrease the amount of bacteria and nutrients entering the lake from the immediate watershed.

6.2 Maple Lake Key Lake and Water Quality Findings

The overall quality of the Maple Lake aquatic ecosystem is fair to poor because it possesses moderate to high nutrient concentrations, low water clarity, elevated suspended solids and organic matter, and excessive growth of algae and aquatic plants. The lake remains susceptible to infestation by exotics such as Eurasian Watermilfoil, Curly-leaf Pondweed, and Purple Loosestrife. Below are the overall key findings from this study that ultimately lead to suggestions for the successful management and protection of Maple Lake.

6.2.1 Maple Lake Water Chemistry

Based on all of the water chemistry parameters, Maple Lake may be classified as eutrophic. Eutrophic lakes with abundant residential development and nutrient inputs are vulnerable to excessive nuisance aquatic plant growth if the nutrient loads are not decreased over time. The sediment nutrient concentrations (bottom phosphorus) around the lake are high, and are the dominant source of food for photosynthetic plants and algae. Concentrations of both phosphorus and nitrogen are likely to increase as nutrient inputs to the lake from the surrounding watershed continue.

6.2.2 Maple Lake Aquatic Vegetation

Native submersed aquatic plants (i.e. Pondweeds and Chard) within Maple Lake are plentiful in shallow littoral zone areas (i.e. between 5-10 feet); however, these communities are currently stressed by the invasion of Eurasian Watermilfoil and Curly-leaf Pondweed which threatens to displace them. Furthermore, the presence of M. spicatwn at depths of between 5-10 feet indicates the ability of this plant to colonize a vast majority of the Maple Lake littoral zone. Floating-leaved aquatic plants are rare in the Maple Lake due to the high sediment loads and inability to successfully grow under those environmental conditions. Emergent aquatic plants are plentiful around some undeveloped and riparian shoreline areas of Maple Lake and are critical habitats for insects and other lake biota. Additionally, they function as erosion guards by stabilizing beach sands that may wash into the lake.

 


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