Wednesday, April 10, 2019

Minto Bridge in Flood - Will we See the Path Covered?

This is now mainly trivia, but during planning and construction for the Minto Bridge, it seemed important. The City never really made it very clear when high water would actually close the bridge or even submerge it. They talked about making the bridge deck itself above the "100 year level" - something like the 1964 flood, with the river at about 38 feet - but the path system itself is considerably lower than that 100 year event elevation, and the City never discussed in public when high water might cover the path.

But with the river now projected to rise to about 27 feet - edging towards 2012 levels, but many feet short of 1996 or 1964 - we may get to see the path covered.

"Closed"? What does that mean?!
(yesterday evening)
Since we've been talking about the bridge, it's become clear that enough parts of Minto Park take on water when the river is at about 20 feet, the City closes the park.
This week we are going to crest near 27 feet. Minto Park has been closed for a few days. Some of the lower paths near or across slough-ish areas inside that park are already submerged and have been for a while.

Around 24 feet on Tuesday, cresting near 26 feet
But it's been updated to nearer 27 feet for tomorrow
 - via NOAA
For comparison, the 2012 flood was a little over 29 feet. At the time, the City swore that the path would not have been covered, but this seems unlikely and false.

We may get to find out!

The water's getting close to the bridge...
(again, photos from yesterday evening, at about 24 feet)
With the river at 24 feet, it's still got another
two or maybe three feet before it covers the path
At this point it does not seem to matter very much that flooding and high water impact the path system. Sure, there are maintenance questions, and in a high enough flood, much higher than this one, perhaps even structural questions for the bridge, but here we're talking just about service interruptions during lesser flooding.

And only when the City was making exaggerated claims for the trail as a "commute corridor" was this interesting. Intermittent closure from high water does not really diminish the value of the bridge and path system as they are actually used. People are using the bridge for recreation, usually doing loops from a parking lot, not through travel, and it is no great problem when bad weather hampers that recreation. People adjust.

So this is just trivia. Maybe today or tomorrow the path will be covered and we will see the answer.

Update, April 11th

Yes, the path has flooded!

At midday the river was at about 27 feet,
and water covered a good length of the path

1 comment:

Salem Breakfast on Bikes said...

Updated with new photo and link to longer discussion of the path's submergence.