Silver Lake is a 70-acre groundwater drainage lake located within the City of Portage in Columbia County, Wisconsin. Because of its proximity to a city park and the city center, local residents and visitors enjoy it daily throughout the year. It is appreciated by those who use it for its natural beauty, peace and tranquility, wildlife viewing, and recreational opportunities including swimming, fishing, boating, and canoeing/kayaking.

The most recent aquatic plant survey conducted in Silver Lake provided guidance for the development of this plan. This comprehensive survey based on the point-intercept method, was conducted in July 2017; a subsequent survey targeting the non-native curly leaf pondweed (Potamogetan crispus) was conducted in May 2018. Twenty-three aquatic plant species were found in Silver Lake (Table 1), with the greatest diversity located near groundwater inflow areas along the north side of the west basin. Aquatic mosses and filamentous algae were also noted. In 2017, the most common plant species was Eurasian water-milfoil (Myriophyllum spicatum) which occurred at 73% of sites. Coontail (Ceratophyllum demersum) at 41% of sites and largeleaf pondweed (Potamogeton amplifolius) at 39% of sites were also prevalent plant species.

To understand a lake and its water quality, fish and wildlife, and recreational opportunities, we need to understand its physical characteristics and setting within the surrounding landscape. Silver Lake is located in the city of Portage, with one public boat landing located on the east side of the west basin. Silver Lake is a 74-acre spring lake with groundwater, surface runoff and precipitation contributing most of its water and the water leaving through a wetland complex on the east side of the lake. The maximum depth is 42 feet in the west basin and 16 feet in the east basin; the lakebed has a moderate slope (Figure 1) and its bottom sediments are mostly muck with areas of sand.

Columbia County LWCD, with participation by City of Portage and UW-Extension, Stevens Point will conduct a comprehensive data collection and planning effort to improve Silver Lake. Two grants work together for this goal. This grant will develop a watershed and water quality modeling tool. They will conduct a shoreland inventory, and a groundwater investigation will be performed. A linked watershed/water quality model that combines urban hydrology and in-lake phosphorus will be developed. Through meetings and a social survey, user perceptions and attitudes will be gaged, and used to inform the development of the lake management plan and will help to identify strategies which are more likely to produce success in implementation.