Learning from Changes in our Creeks

Waterloo Creek after November rains

Change is inevitable. Sometimes it is sudden and unexpected. No one saw a pandemic coming a year ago. Other times, change is the result of hard work and intention. Three years ago there was precious little information on the health of our local creeks. Now we have rich data sets to pore over. But the type of change most prominent this time of year is cyclical change. 

In early October, we had warm weather with bright sunshine. Not unusual for this time of year. Then we had a bit of rain and our creeks, to varying degrees, responded with more flow. But the night before a recent sampling expedition, it rained buckets throughout the night and was raining when we headed to the woods. Hart Creek, normally a tame little dribble of a creek, was roaring. The roiling water had a milky, dirty look and the turbidity was quite high at 16 NTU. Cowie, which is often the colour of weak coffee, was a muddy mess. Wilfred was so swollen that it had created a swamp where we normally take our readings. Stagnant water isn’t what we want so we had to improvise, wandering downstream until we found a spot that wasn’t a newly created wetland.

The seasonal changes we see in our creeks and wells follow a yearly pattern. These changes are familiar and we have two years of previous readings to help validate our results when they change dramatically. Turbidity is high in Cowie? Ah, yes, it was quite high last year around this time. Conductivity seems low in Wilfred? That makes sense, it did that last time there was a big rain event just before sampling. We emphasize this process when training new members. It’s not enough to simply write down the readings. We have to consider: “Do they look reasonable?” 

I can personally relate to this. I learned it the hard way. Last year, while calling out numbers to my sampling partner, a new sampling trainee, we managed to turn a thirteen into a thirty. When we returned from sampling, someone with sharper eyes than mine pointed out that it was physically impossible for dissolved oxygen to be that high. If I had glanced at recent records, which I now do diligently, I would have caught the error and we could have resampled and corrected the error. Instead, there is a small hole in our dataset.

And when there is no previous data? The recent high turbidity in Hart Creek posed a methodological challenge because we only recently started sampling this creek. We did not have seasonal baseline data for comparison. So we resampled several times to rule out measurement error and ensure reliability of our data.

Change comes in many forms: seasonal, climate-induced, meteorological and procedural to name a few. Change is inevitable and if we pay attention it can be a source of wisdom. 

Leave a Reply

Your email address will not be published. Required fields are marked *