Saturday, October 23, 2010

Wilket Creek: Troubled Watercourse

Map of Wilket Creek (click to enlarge)

Wilket Creek is a tributary of the Don River. Its headwaters (now buried) were once in the Willowdale and Sheppard area of North York. It appears above ground northwest of Bayview and York Mills and continues open until it joins the West Don River near Leslie and Eglinton Avenue East. Except for a short section just north of Lawrence Avenue East the creek travels through public parks. There are two ponds, one in Windfields Park and the other in Edwards Gardens. Both are manmade and kept in place by small dams. The most well known section is the Wilket Creek ravine that runs between Edwards Gardens and the Don River. This section is also the most problematic and in recent years has been hit hard by flooding.

Recently signs have appeared at the entrances to the Wilket Creek ravine. The signs talk about the start of a geomorphic assessment of the creek. In lay person's language they are going to study the way water flows through the river channel and why flooding is causing damage to the trails and bridges.

The Toronto Region Conservation Authority put the study out to tender and a local company called Parish Geomorphic won the bid. They will study the creek and make recommendations for improvements. For all this they will be paid about $300,000. This may sound like a lot of money but it you want scientific expertise it costs money. Parish did a similar study on Burke Brook a little upstream so they have local experience.

The study will map out the creek in detail and will describe physical conditions of the creek bed and underlying soils. It will also map the natural water input as well as the manmade stormwater sewers that feed into the creek. It is the latter that is the main culprit for flooding. Most of the water that falls on the surrounding neigbourhoods ends up in the creek. When it rains heavily this is a lot of water. In August 2005, July 2008, and July 2009 there was so much water flowing in the creek that it destroyed the pedestrian bridges and obliterated the walking path through the ravine.

Woody debris choking river channel under a bridge in July, 2008

Winter 2009. Note the wide channel and scoured banks

It's a well known fact that too much water is flowing through Wilket Creek during storms. I'm a little puzzled by the need for a full blown study and I can't see that they are going to come up with anything really new. Basically what they will find is that Wilket Creek is a typical urban stream with several storm sewers that can dump large amounts of stormwater into the creek very quickly. All this water overwhelms the creek and the fast water overflows its small channel. The small pedestrian bridges and the cheap asphalt paths are no match for all this water and are easily damaged.

There's an easy sounding solution for all this - reduce the stormwater flows into the creek. Remove the excess water and the problem is solved. Unfortunately, diverting the stormwater means very expensive underground diversion to storage tanks and pipes. Building this will take considerable finances and political will.

So perhaps the purpose of the study is to give someone sufficient reason to build these systems. In order to spend millions of dollars on vital infrastructure you need an expensive study done by a reputed company and not just the opinions of concerned volunteer citizens who know the area but don't have the credentials to back them up.

Sign posted at mouth of Wilket Creek

1 comment:

Nicholas said...

I went to a City presentation a couple of years ago about how they were going to widen the watercourse, and build wider bridges as a solution to the Wilket Creek flooding problem.
So why is another study taking place now, when they supposedly had a solution two years ago?
Is this another waste of taxpayer's money!
I would like to know if providing better run-off capture in the area north-west of the Bayview and York Mills intersection would solve the excess flow problem further south. At this point the creek is in a tunnel, but it runs through a large ravine area with plenty of space for catchment ponds.
Also how much does the urban intensification of the Yonge-Sheppard corridor affect the lower creek? The creek did not flood before 2005, which was roughly when the Yonge-Sheppard area was being rapidly converted from single family homes with garden catchment to condo towers.