A Lighter Topic -- Quabbin, Wachusett, and Ware

 

After discussing how hard it is to combat racism and how bleak the political outlook is, I figured it's time for a lighter topic.

A few decades ago I learned a bit about the system that provides water to Boston and surrounding communities. Here's the gist: Quabbin is a big reservoir far away, and Wachusett is a smaller reservoir half way to Boston, and the Ware River is halfway between the reservoirs. What I learned then is that there is a tunnel from the Ware River to the Quabbin, and depending on conditions, water might flow through the tunnel east or it might flow west. When there's lots of water flowing (like, lots of rain), the excess Ware River water goes west to help fill the Quabbin. When there's less water, the Ware River is undisturbed, and water from Quabbin flows east past the Ware River and into the Wachusett reservoir. I thought it was very clever.

The web did not exist when I first heard of this a few decades ago, but now it is so easy to get information! I checked today to see if it's true, and apparently it is. What's more, it's still true (you can imagine water usage patterns changing in the interim). The system is a little bit, kind of, like breath feeding bagpipes. The bag holds enough air you don't need to breathe into it all the time.

The Ware River is of course long, and the key point on it for this purpose is the Ware River Diversion.

Today the new thing I learned is that sometimes (when Ware River water is about to be shut off, I think), it is used to fill a natural siphon that lifts the Quabbin water high enough so that near the Wachusett it is used to generate electricity. Detail: the turbines can only handle so much water, though, so if there's more flowing east, then some of it is diverted straight to the Wachusett.

Reasoning about it, it looks like while the Ware River water could be used to generate electricity when there is plenty of water, it is more valuable as water to be used later than a source of power, so the water flows west and the turbines sit unused.

Figure 3 in <this paper> is the one I can make most sense of. First, note that the Ware River is way up in the air compared to the two reservoirs. Since when is a river higher than the land on both sides of it? In this case, I guess it is.

The western pipe has to be deep enough that it can feed water eastward even when water levels are very low. But that is so deep that you can't make use of the water's drop in elevation to generate power when water levels are higher. The siphon lets them take that water heading east and then lift it up high enough so they can get power out of it when it goes downhill again, near the Wachusett.

Or maybe the pipes near the Ware River aren't all that deep, and the system relies on a siphon to just get the water out of the Quabbin even when water levels are low? I can't tell.

I didn't even try looking at the subject of the paper. The idea is that humans have to make decisions about how to set the various valves, and optimal operation requires the right decisions. The paper describes dynamic prediction about this. Lots of scary equations there. But I thought the basic plan was interesting enough to write about!