The Valley is in fact a part of the Humber River watershed. After we had a hurricane in the fifties that washed out a part of the area, it was redeveloped. That's why it's houses are newer than the rest of the areas in West Toronto.
Most of the semi-detached houses in The Valley have been built in the early sixties of the last century. Most of them have nice sized gardens. Also, low traffic caracterizes this neighbourhood, making it a much sought-after area. This is where a young family would buy their first home.
One of the benefits of The Valley is that it is able to cater to all price points, so a family doesn't have to leave the neighbourhood where they bought their first home.