Water Quality -- Causes, Effects, and Solutions

water quality photo wading birds

Silver Lake's surface water quality is a crucial indicator of environmental health and the sustainability of this valuable southeastern Wisconsin resource.

Overview

Surface water quality can be influenced by aquatic ecosystems as well as agricultural, residential, and commercial factors.  These influences can lead to problems such as harmful algae blooms and oxygen depletion.

For example, agricultural and commercial/residential runoff, rich in fertilizers and possible storm sewer discharge, can degrade water quality.  Nitrogen and phosphorus from fertilizers contribute to toxic algae growth, which can harm fish and make the water unsafe for recreation.  Additionally, external factors such as invasive species and road salt can further degrade water quality and affect plant and fish diversity.

Silver Lake has been designated as a critical aquatic habitat under the Southeastern Wisconsin Regional Planning Commission's (SEWRPC) Critical Habitat Designation Program due to its supporting an ideal wetland habitat for waterfowl, marsh wildlife, and critical fish species (SEWRPC Planning Report #42 September 1997).  The WDNR has also designated two areas within Silver Lake itself as Environmentally Sensitive Areas.  Silver Lake is also home to two minnow species that are designated endangered, threatened, or special concern fish species.

The most important natural resources are found in the environmental corridors and isolated natural resource areas in and around the lake.  The preservation of these areas -- highlighted in green and yellow on the map below -- is of the utmost importance.

Specifically, Silver Lake's primary environmental corridor covers nearly 1,000 acres (including both lake and land), with the the lake's watershed spanning over 2,780 acres.  The size of the watershed is significant, as its natural vegetation and soil act as filters, removing pollutants and improving water quality before reaching the lake.  Silver Lake's watershed-to-lake ratio is a modest 5.2 to 1.  In contrast, lakes in developed areas with a ratio of 10 to 1 tend to develop water quality problems.  Both the watershed and protected areas of Silver Lake serve as natural buffers against harmful pollutants by enhancing water quality, adding nutrient buffers, providing biological and physical zones, micro-habitats, and sediment stabilization.  These primary corridors have immeasurable environmental and recreational value.

SEWRPC envir corridors

Silver Lake Water Quality Analysis

Silver Lake is highly alkaline (high pH) due to the slow dissolution of carbonate-containing rocks over time.  This "hard water" is beneficial, as it helps maintain stable water quality and creates a favorable environment for fish and aquatic plants.

High levels of sodium, potassium, chloride (salt), calcium, and magnesium are concerning, as some of these readings have continued to rise from 2001 through 2024, primarily due to road salt and brining for de-icing.

Both Total Kjeldahl Nitrogen and Total Phosphorus levels have remained stable over the extended measurement period.  These low and stable levels help minimize algae growth and blooms in the lake.  Similarly, Secchi disk depth and Chlorophyll-a (measurement of suspended algae in the lake) have remained relatively stable from 1993 through 2023.  Efforts to manage these readings are discussed below.

Ongoing Monitoring

Silver Lake's surface water quality has been monitored since the late 1980s by Citizen Lake Monitoring Network (CLMN) volunteers, who measure clarity (Secchi disk), chlorophyll-a, phosphorus, and nitrogen.

More comprehensive water quality testing was conducted in late 2001 and again in the spring and fall of 2024.  These and other reports can be found here:

In April 2025, the Silver Lake Management District requested SEWRPC to propose a comprehensive water quality study proposal that will confirm sanitary disposal on riparian and watershed parcels, investigate storm sewer outfalls, identify sources of repeated summer beach closures, and provide grading of riparian parcel run-off with recommendations for improvements.

Call to Action

Residents can support the lake by adopting the following practices:

  • Increase vegetated, natural shorelines with trees, bushes, and diverse ground cover along the water's edge.
  • Stabilize shorelines and reduce run-off by implementing solutions such as rain gardens.
  • Reduce fertilizer use and create planted buffer zones near the lakeshore.
  • Support local conservation groups and adopt eco-friendly habits to promote responsible water use.
  • Continue participation in the CLMN and conduct periodic, comprehensive surface water quality monitoring.

Local Conservation Resources