Toronto Islands - Geography and Climate

Geography and Climate

The area of the islands is about 230 hectares (570 acres). The largest, outermost island, called Centre Island, is crescent-shaped and forms the shoreline of both the Eastern and Western Channels. Algonquin (Sunfish Island) and Olympic are two of the other major islands. The former is mostly a residential area and the latter home to the city's Island Public Science School. What is commonly called Ward's Island is actually the eastern end of Centre Island and like Algonquin is a residential area. Confusingly, Centre Island Park is located on Middle Island, which is as a consequence often mistaken for Centre Island. Centre Island is sometimes referred to as Toronto Island (note the singular form) to prevent this type of confusion. Other smaller islands include:

• Forestry Island – heavily forest and no fixed link to other islands
• Snake Island – partially forest and beach facing Toronto Harbour (Snake Island Park); access from bridge to Centre Island
• South Island – used for mooring and on land storage of boats by the Royal Canadian Yacht Club; east end of island cut off at Chippewa Avenue
• RCYC Island – occupied by Royal Canadian Yacht Club

Two unnamed islands occupy what was once Block House Bay:

• ringed island in Long Pond (the former water intake of the City of Toronto) – located across from Mugg's Island
• small island in Lighthouse Pond

The islands were originally a 9 km peninsula or sand spit extending from the mainland. The islands are composed of alluvial deposits from the erosion of the Scarborough Bluffs. The flow from the Niagara River to the south across Lake Ontario causes a counter-clockwise east-to-west current which has, over time, deposited sediments at the south end of the harbour to form a sand spit.

In 1852, a storm flooded sand pits on the peninsula, creating a channel east of Ward's. The channel was widened and made permanent by a violent storm in 1858. The channel became known as the Eastern Gap. The peninsula to the west became known as the Toronto Islands. To the east of the Gap, the area of today's Cherry Beach was known as "Fisherman's Island".

Sediment deposition was halted in the 1960s when the Leslie Street Spit was extended beyond the southern edge of the islands. Left to nature, the islands would diminish over time, but this is limited due to hard shore lines built to limit erosion. Over the years land reclamation has contributed to an increase in the size of the islands. The harbour was shallow with a sandy bottom and the sands were moved by dredging or suction methods. Ward's Island was expanded by dredging. Today's Algonquin Island, formerly known as Sunfish Island, was created from harbour bottom sands.

The area now occupied by the airport has been subject to several landfills over what was once sandy shoal, initially to accommodate the amusement park that preceded the airport, and then to accommodate the airport itself. The Western Channel to the north of the airport is several hundred feet of the original western channel, which was just south of today's Fort York. It was opened in 1911 as part of a program to improve boat navigation into the harbour. The airport lands were created from harbour sands in the late 1930s.

A series of waterways allow boat traffic to navigate the island:

• Allan Lamport Regatta Course - located between Centre Island and Middle Island from Long Pond to east end of Farm Enough Farm
• Block House Bay - located on east side of Hanlan's Point
• Lighthouse Pond - located next to Gibratar Point lighthouse
• Long Pond - located between Allan Lamport Regatta Course and Block House Bay
• Snake Pond - located between Snug Harbour and Algonquin Island
• Snug Harbour - located between Snake Island and Olympic Island
• Trout Pond - loocated west of Lighthouse Bay on the south end of Hanlan's Point

The climate differs from the mainland in that cooler lake waters surrounding the island cool spring, summer and early fall daytime temperatures by 2-3C, on average. In winter the unfrozen lake waters are sometimes warmer than the air, temperatures are roughly equivalent to the downtown area but warmer than areas further away from the lake. Fog and low-clouds are more frequent at the island on the mainland. Near shore areas of the lake only freeze after a consistent period of sub-freezing weather.