With the lake level higher than it’s been in several years, it follows that outflows from the lake should also be at levels not seen for quite some time. Well I had occasion to measure the outflow from Clary Lake this morning, out of curiosity as much as anything and sure enough, based on my calculations the current outflows as of the time of this writing are on the order of 83 cfs (cubic feet per second). The raw figure I arrived at was 98 cfs but it is customary to scale that figure down by as much as 15% to allow for flow losses resulting from friction on the sides and bottom of the stream which inevitably result in uneven water velocity and a lower overall flow value.
I estimate that about 55 cfs of water is flowing out of the dam’s outlet pipe and the rest of the water, about 30 cfs, is the result of water leaking through the hole in the dam and from seams on either side of the outlet. That there is a substantial amount of water leaking through the hole and cracks is apparent just by standing on the side of the road and looking at the downstream face of the dam. Here’s a short video I took this morning. What you can’t see in this video is the water leaking through the dam on the left side. It it essentially leaking across the entire face of the dam:
I was also able to estimate the water level at the dam to a high degree of certainty by making careful measurements of a photograph. The figure I arrived at is -18.8″ ± 0.5″ below the top of the dam. What is interesting is this is about 2″ HIGHER than the water level of -20 .80″ below the top of the dam that I recorded this morning by my place. While this might seem wrong at first glance, it is both expected and explainable. This is not the first time I’ve found water levels at the dam to be higher than at the lake. This often occurs after large runoff events such as we’ve seen this past week. I expected to find this to be the case when this morning I recorded a 0.02′ rise in the lake level from yesterday afternoon. Peak runoff was yesterday so today the level should have been the same, or slightly lower than yesterday. The obvious explanation of this phenomena is that water is still flowing into the lake faster than it is flowing out and there’s only one place where that water could be coming from: the meadow. I’m going to take a walk up to the outlet later this afternoon and I fully expect to find the channel flowing INTO the lake, not towards the dam.
So now the only question is whether AquaFortis Associates LLC is going to exercise their right to sue Pleasant Pond Mill LLC for allowing more than 50 cubic feet per second of water to flow out, over, or through the Clary Lake dam. Time will tell. Clearly, as the picture at left shows, the outlet pipe in the mill pond is unable to handle the flow out of Clary Lake as it is completely under water. The only reason the mill pond hasn’t filled up with water is because it’s leaking out through cracks in the dam and in the headwall of the building foundation. They’re going to want to fix that.