You’ll be surprised to know that it’s been raining in Portland, our second wettest spring on record .
Even so, there is only minimal deviation from the historical norms of annual precipitation, just a bit over five inches of rain in April. Even the record extremes have limits: if one plotted the extreme highs concurrent with extreme lows, you’d see a wide stream in winter (a variance of nearly a foot of rain) evaporate through spring to a trickle in July and August (about a three inch band only).
Even in extreme, the patterns mean something – our geography and climate can only generate so much rainfall. The Northwest’s moderate latitude, coastal mountains and inland valleys have made for lush forests and sweet meadows – it’s a superb place to grow spearmint, hops, grass (both kinds), and berries of all sorts.
The two graphs – annual rainfall and extremes – tell us nature’s water story in the Pacific Northwest. It wasn’t until the newsletter from my local water district arrived, that another story emerged – what humans do when the water runs are low.
In my local water district (Milwaukie, OR, just south of Portland – I’m literally three blocks from Portland), annual reports tell us about pumping and pollution. Here, I include the pump rates from the previous four years. Not much of a surprise there – we need the water in July and August. What gets particularly hairy is if the snow pack is off a bit. Couple that with our population taking off in the recent years, and there are multiple feedback loops impacting both our annual rainfall and the deep aquifer that we all rely on.
Amid all this, I started to imagine a model: surface water to ground water to aquifer, and then the increasing demands emerging from our population increase.
At this point, our aquifer is not in danger of being depleted . . . but there are a few that have been – some are just a local farmer’s well, others are quite large.
In Georgia, you can see both the annual recharge as well as the steady water decline as urban dwellers suck more deeply on the big straw poking into their water table.
Here in the currently sopping Northwest, we don’t worry overmuch about this. No surprise there . . . we won’t worry until some feedback comes our way: higher water bills, government recommended flushing habits, a ban on car-washing or lawn watering in August, or – God forbid – rationing.
Our record cloud cover and spring rainfall amounts are indeed a silver lining.
- OneThing25: water rules the world (itsallonething.com)
- Aquifer’s Depletion Poses Sweeping Threat (green.blogs.nytimes.com)
- WA dams set to dry up by summer’s end, expert warns (theage.com.au)