Last Updated: 11/09/2022

Latest Update

11/9/2022 Update:

The Warner Lagoon Water Quality Plan Final Report is available. Thank you to all those involved in this effort.

Water Quality Planning Process

Aerial Photograph of Warner Lagoon

The City of Madison is in the process of spearheading a water quality planning process for Warner Lagoon. This effort is the result of public concern over the health of the lagoon and the fishery it supports, and it was requested the City take a more proactive approach in improving the lagoon as a resource.

Goal Definition

The first step in any planning process is to develop a concise list of objectives that inform the plan development. In this planning effort, those goals were determined by meeting with the lagoon’s many stakeholders, as well as the general public, to flesh out a unified set of objectives. After a series of stakeholder meetings and a public listening session, it became clear that most people wanted the same things from and for the lagoon:

  • Maintain or Improve Recreational Opportunities (fishing, paddling, bird watching, passive nature enjoyment)

  • Improve Water Quality

  • Maintain and Improve Habitat

  • Continued Shoreline Access

  • Continued Naturalization of the Large Island

Plan Development

The intention of the planning process is to develop a document, which is agreed upon by the majority of participants, that proposes realistic projects that work toward achieving the defined objectives. This document will be used to plan future projects when resources become available.

Through a competitive bid process, the City hired Montgomery Associates Resource Solutions LLC, now Emmons & Oliver Inc (MARS-EOR).  The consultant was tasked with translating the objectives listed above into tangible and realistic projects.  They spent approximately 18 months working with City Engineering, City Parks, the Department of Natural Resources, and the stakeholders to develop this conceptual layout.  It should be noted that MARS-EOR was limited in scope to developing solutions that could be implemented either within, or immediately adjacent to the lagoon.  Although water quality is a watershed scale issue, City Engineering continuously looks for "upstream" water quality solutions. 


Stakeholders that have been involved in the process include:

  • City of Madison Engineering Division
  • City of Madison Parks Division
  • Alders from Districts 12 and 18
  • Wild Warner Park
  • Yahara Fishing Club
  • Dane County Conservation League
  • Wisconsin Department of Natural Resources
  • Members of the Public


Warner Lagoon is a 28 acre, shallow, man-made lagoon that is hydraulically connected to Lake Mendota by a 72-inch concrete pipe on the western edge of the lagoon.

The lagoon was dredged in an area known as Castle Marsh. The marsh was created with the 1912 construction of Tenney Locks, which raised the water levels of Lake Mendota by approximately 5 feet. Prior the installation of the locks, the area was low-lying farmland.

1937 Aerial Image of Castle Marsh
1937 Aerial Image of Castle Marsh - Warner Lagoon had not yet been excavated.

The lagoon was constructed in the late 1950's and early 1960's by the City of Madison in conjunction with the Department of Natural Resources. It appears the lagoon was developed for a variety of reasons, including:

  • To increase recreational opportunities,
  • To create additional park land
  • To protect Lake Mendota from storm water runoff from recent development
1950 Aerial Image of Warner Lagoon
1950 Aerial Image of Castle Marsh - Although the shape is reminiscent of the existing lagoon, excavation had not yet begun.
1968 Aerial Photograph of Warner Lagoon
1968 Aerial Image of the First Phase of Warner Lagoon

Over the years, not only has the water quality deteriorated in the lagoon, but the lagoon has become an asset to the community in its own right. Therefore, the City and others are exploring ways to potentially improve the lagoon and its immediate surroundings.

This article by Trish O'Kane on the Wild Warner Park website provides more background on the history of the lagoon.

1975 Aerial Image of Warner Lagoon
1975 Aerial Image of Warner Lagoon - By the early 70's, Warner Lagoon had been excavated to its full extents.