Weather is not Climate

The Bulletin ran a story last week on the local snow pack which reminded me that I had not posted on this topic since last spring.  The winter is a little less than half over and so far the snow pack looks pretty good, but all is not well.  Weather is not climate, Oregon remains drier than normal, groundwater levels are going down, and we continue to allocate water based on 100 year old water laws which were written in a very different environment.  Keeping reading for more.

First, the good news is that the snow pack across the state is close to normal, although low near population centers.  Of course, over half of the winter is still in front of us and we need the snow to keep falling.  Last year we went from extremely low snow pack, to above average, back down to 50% of average in Central Oregon by the end of the winter.  Even with a huge snow fall last February, by spring the snow was gone, it was clear that Wickiup Reservoir would not fill, and North Unit Irrigation District had to cut back water deliveries to farmers by 25%.

SNOTEL 2.1.20

The importance of snow pack cannot be over emphasized.  Central Oregon has prospered for the simple reason that it has benefited from a history of heavy snowfall in the Cascades combined with cool weather.  There is no better water storage than snow.  We simply cannot build enough reservoirs to match the water storage equivalent of a healthy snow pack.

If you have lived here for a while you know the complaint about “Juneuary”: June being as cold as January.  It lightly snowed on July 4th the year I arrived.  Talk to anyone who has lived here for more than 15 years and they will tell you it did not get hot until August and then for only a couple of weeks.  Most homes were not air conditioned as it was simply not needed.

Our previously cool weather slowly melted abundant snow in the Cascades, releasing  enormous amounts of water over most of the summer.  This slow water release seeps down into the young, porous volcanic rock that makes up the eastern slope of the Cascades, replenishing the aquifers and springs that feed our rivers.  As a result, the Deschutes, Metolius, and the Fall rivers historically had amazingly stable flows.  In contrast, the Crooked is a “flashy” river, primarily fed by surface flows which are highest in the spring.  The Crooked is fed by a watershed where the geology is much older and less permeable, allowing for less seepage and groundwater recharge.

It is undeniable that our climate is warming.  For over two decades we have not had a consistent, slowly melting snow pack and we remain in “abnormally dry” to “moderate drought” conditions.

Drought Monitor 1.28.20

Here’s a graph that shows how the last 20 years have looked in Oregon.  Over the past 20 years large parts of the state have been in “D3” conditions, or extreme drought.  In fact, there are only a few periods where we have not been in at least a “D0” or abnormally dry.  So, while the snow pack is approximately normal today, we need to remember that weather is not climate.  Our climate is warming and drying.

Drought in Oregon

Clearly, precipitation, snow pack, and warming temperatures dramatically impact rivers and lakes and the fish and wildlife that depend on them.  We are getting less snow, our aquifers are lowering as they are not replenished, we continue to pump more out of them as our population grows, and about 90% of our water continues to be used by irrigators who often are not producing viable agricultural commodities.

Water policy in Central Oregon is broken.  It will have to be more holistically addressed to avoid a crisis in the foreseeable future.