Comments on: A2: Argo Spillway

By: Ross Orr (Voxphoto)

Ross Orr (Voxphoto) — Mon, 30 Nov 2009 17:48:56 +0000

Nov. 30th update: The mystery may be solved. As the water level has dropped, another outlet to the millrace has surfaced, a couple of yards to the east of the spillway.

This muck-covered grille is making gurgling water noises, and presumably connects through the Edison substation in some way…

By: Ross Orr (Voxphoto)

Ross Orr (Voxphoto) — Sun, 08 Nov 2009 22:25:17 +0000

I’m concluding the real wild card is whether any water still passes through the Edison Substation’s disconnected hydropower equipment.

I assumed not. But investigating further, I discovered the concrete pedestrian path below the south corner of the substation has a rather hidden outlet grille beneath it. (location–foot of the steps here: Google Maps Link )

Dropping some twigs in the water, there did seem to be a barely-perceptible downstream flow emerging from that. Enough to explain 70,000 gallons in one day? I couldn’t guess.

By: Russ Miller

Russ Miller — Sun, 08 Nov 2009 20:00:36 +0000

Evaporation is probably a small effect. Mean pan evaporation around here for October is ~3 inches/month and free surface water evaporation is usually estimated at 75% of that, so we should expect less than 0.1 inch of evaporation per day. Historical pan evaporation data [link to .pdf file]

By: Ross Orr (Voxphoto)

Ross Orr (Voxphoto) — Sun, 08 Nov 2009 18:50:10 +0000

I originally observed a 1-1/4″ drop between midday Thursday and midday Friday. That was before the recent warm & sunny weather–it was basically cloudy & cool. But you’re right that I haven’t tried to estimate evaporation.

By: Tom Whitaker

Tom Whitaker — Sun, 08 Nov 2009 16:34:28 +0000

Evaporation perhaps? It’s been quite warm and breezy. Anyone who’s ever maintained a swimming pool can tell you that they lose a lot of water daily due to evaporation. Maybe it doesn’t explain the total amount, but I bet it’s not an insignificant factor.

By: Dave Askins

Dave Askins — Sun, 08 Nov 2009 16:00:09 +0000

For a layout and more complete narrative of the photos, Voxphoto has put together the following: [Link]