Monday, October 25, 2010

A Rainy Day

Surface runoff harms the Gorge
It is on a rainy day like today that I can see the problems of water management that we have in this region.  We simply have too many impervious surfaces  - houses, roads, parking lots, buildings, hard packed earth and more.  Added to this we have very few natural water retention systems left like wetlands, swamps and water courses.  This means we have water levels in creeks, culverts and sewers rise and fall quickly and a lot more of the rain flows through our city as surface water and no longer goes into the ground.  Is this is a huge problem?

On the scale of world problems or even environmental issues in this region, the water flows from the rain are not a big deal, but if we had been thinking ahead we would not have the problem at all.  In my case it is a bit higher on the radar because I live near the Gorge Waterway and like to boat on it and swim in it.

Less than half the surface is able to soak up the rain and it is the areas that could soak up the most that have been lost.  We have built our city in such a way to be almost completely at odds with the natural water cycle for our area.  We have caused more problems for everyone by having surface water quickly rising to levels of near flooding in many areas of the city and then overburdening our storm sewer system.   These widely fluctuating water levels are a problem but not as big a problem as the fact we have a lot more surface water.

In the past much of the water would have seeped in the ground and then flowed through the soils to the creeks and rivers.   This process filtered the water meaning what ended up in the creeks and lakes was cleaner than it is today.   On top of this is the fact that our roads have a build up of petroleum related waste from all the vehicles (engine oil, grease, hydraulic fluids, gasoline and diesel) - this the sheen water on the edges of streets often has.  All this is sweep along and quickly accumulated on the streets.

There are things we could be doing:

This could have been a good bioswale

  • Bioswales  - there is one downtown now on Blanshard outside of the new Atrium building and Saanich has put some in on Shelbourne in Gordon Head.   These are small artificially created landscape elements that allows water to accumulate and then filter into the ground.
  • Encouraging large paved areas to be broken up with some locations that allow for water to filter into the ground.   I am talking about taking every tenth to fifteenth parking spot and making them a garden bed.  I know there are supposed to ways to pave that allow for water to filter into the ground, but I am not convinced they work well because the ground becomes so compacted that it does not allow for any water to penetrate.  Hard packed soil is also impervious.
  • Working with existing water courses and building ponds and more wetlands into them to allow for water to be retained.  As an example, Colquitz Creek between Burnside road and Silvercity could be altered to make the area to the west of the Tillicum mall parking lot a wetland area.  The existing area of Cuthbert Holmes park is not currently used for anything and would benefit from this change.  This would mean spending money on heavy equipment to make the contours needed to allow the area to become a wetland and I do not know how much spending makes sense.   There are similar opportunities with Bowker Creek and Cecilia Creek

As I said earlier, this is not a big deal, but it is one of those many small things that would not take a lot of change for us to make a big difference.  In the case of Colquitz creek, the change would dramatically increase the salmon runs on the creek.
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