The Westminster Ponds/Pond Mills complex is one of the largest Natural Areas in London, comprising some 300 hectares over an area 3 kilometers long and 1.5 kilometers wide. There are six major ponds and a number of smaller ones scattered throughout the area. The Westminster Ponds area is significant because it possesses a rich variety of natural habitats in a relatively undisturbed state, even though it is situated within the boundaries of a major urban centre. In fact, this marsh, swamp and bog complex is a Class 1 provincially significant wetland.

The ponds occupy kettle depressions made by large blocks of ice which were left when the last glacier started melting 13,000 years ago. They occur in the Ingersoll moraine, an east-west ridge of stony soil (till) deposited by the edge of the glacier when it stopped moving for a period of time. When the blocks melted, the depressions or kettles remained. Angular pieces of white chert and black shale from the till are still found by the ponds. Westminster Ponds is the best group of kettle lakes to have been preserved in the London area.

Much of the land is owned by the City of London or by the Upper Thames River Conservation Authority (UTRCA). The Western Ontario Fish and Game Protective Association owns the pond which now bears its name. Saunders Pond and adjacent lands are owned by the Victoria Hospital Corporation.

Ontario’s wetlands are evaluated through the Ministry of Natural Resources (MNR) Wetland Evaluation System (1993) for their biological, social, and hydrological components and special features.

• This marsh, swamp and bog complex is a Class 1 provincially significant wetland
  
• Provincially Significant Wetlands - Class 1 to 3 wetlands, highest ranking, protected under Provincial planning policy.
  
• Environmentally Significant Areas (ESA's) - significant natural areas, designated for protection by the municipality