Alfred Caldwell Lily Pool

In the early 1950s, under Zoo Director Marlin Perkins, the pool was transformed into a water exhibit featuring exotic birds and water fowl and came to be known as The Rookery. Overgrazing by zoo birds had a devastating effect on the lily pond. A lack of landscaping management allowed invasive plants and "weed" trees to take over the understory. Combined with heavy human foot traffic, uncontrolled erosion, the introduction of plants materials that were invasive to the existing lilies, and inappropriate repairs (eroded areas covered with loose stones) this resulted in what Caldwell called (in 1990) "a dead world".[7][8]

From 1998 to 2002, the 2.7 acre Lily Pool underwent a major restoration by the Chicago Park District and the Lincoln Park Conservancy. The Friends of Lincoln Park (now called The Lincoln Park Conservancy) raised $1.2 million toward the restoration of the lily pools. A similar sum was obtained from a grant from the USDA Forest Service. Wolff Landscape Architecture was hired to complete the project.

Five focus groups were conducted to develop a consensus plan for restoration of the site;[9]

1. experts in historic preservation,
2. bird watchers and ecologists,
3. Individuals knowledgeable about Lincoln Park and active in its planning and management,
4. activists and experts on the subject of accessibility,
5. members of the general public.

The Chicago Park District and the Lincoln Park Conservancy manage a docent program at the Caldwell Lily Pool.[10]