I couldn't measure the tank properly last night. The wind was blowing and the wave action kept the level in a state of high fluctuation. Plus nearly a half inch of rain fell in the night, which would have raised the level at least half an inch, depending on how much ran in from the ramp. Also the tank was 3 feet from being full and doesn't reflect leakage when it's full. My best educated estimate is that it's leaking less than an inch, maybe even not at all. So full, it might leak up to two inches per day, decreasing as the level decreases. It's not likely that the leakage will increase. Normally, when the tank first fills is when the damage occurs, and then it stays constant after that. Unfortunately, I can't measure it tonight because I have to go to Alpine.
A little explanation here of how the system works, for those who are interested, and don't know. There are two arroyos that converge below the oasis before they run into a big steep canyon that isn't on my property. Sometimes one of the arroyos runs, sometimes, the other, and sometimes both (or neither). Since predicting which will run is not possible, it's kind of like Russian roulette. The smaller east arroyo runs most often, so I try to keep the water, that the two dirt tanks there collect, pumped into the stucco tank. It's plumbed for that. But I'm always risking the other (west) arroyo running, and with the stucco tank and other tanks full, the water will run away down the canyon, whereas, if the stucco tank wasn't full, the water would go into that tank and I'd still have the water in the dirt tanks.
But it's not as straight-forward as that. The dirt tanks wouldn't hold it for all that long anyway, and I would have to put gambusias in them to prevent mosquitoes, then watch the gambusias die when the tanks are empty. And they're empty long before I can use the water. If all tanks are full, I top them off from the dirt tanks until they're empty. Especially, when the stucco tank was leaking so bad. I couldn't catch enough water to keep it topped off. It leaked as much as the dirt tanks did. But if I leave the water in the dirt tanks, and that arroyo runs again before the west one does, then the water goes to the ocean, and hasn't helped my storage tanks one bit. So it's always a juggling act, requiring constant decisions.
The largest arroyo (on the west side) has two concrete diversion dams that divert the water into the storage tanks. Water doesn't go over the first dam until the big tank, and wildlife pond are full. This last rain ran enough that the big tank filled up, but didn't overflow the dam. The next rain will have no where else to go but over the first dam to the second dam, which it won't flow over until the stucco tank is full. It takes a quick hard half inch rain to cause the arroyo to flow. So by pumping the stucco tank full, the water will then run to the ocean if it rains and runs down the west arroyo only. The dirt tanks would remain empty. It's early in the season and I'm not concerned either way. My big concern is having the tanks full and not leaking. Because I didn't start pumping water right after the rain, a lot soaked away in the dirt tanks and was lost, so I lack 21 inches of having the stucco tank full until the next rain, which is predicted for tonight. Not concerned. If I hadn't done any pumping, chances are a big rain tonight or tomorrow would have filled everything anyway. But it's not a chance I'm willing to take. A bird in the hand.......
I also will mention that I'd rather pump the stucco tank full than have it fill in minutes from the second diversion dam. More damage is done the faster it fills, plus where it runs in, it also soaks into the ground around and behind the tank wall.* And we all know that's not good. Additionally, when I pump the water in, it has already settled the dirt out of it, so puts less sediment in the tank that I end up having to haul out. And we all know how I hate that job.
A couple of days ago a critter used my hanging feeder for a piƱata. I glued (ShoeGoo) and taped it back together and hung it a foot higher. I think it was a bear. Found a black wiry hair (about 2" long) wedged in one of the feeder's fractures. I don't think a javelina could have reached the feeder. If this solution doesn't work, I'll go back to the metal bucket feeder and construct some kind of perches on the bucket rather than the platform it had that attracted doves and cowbirds, etc.
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* Obviously, any huge rain will cause that to happen, whether the tank is full or not. Just saying my preference is to pump it full. I like enough rain to do that but don't like so much that it inundates everything, then after it's done its damage, it goes to the ocean. I do have a 3rd dam at the edge of my property that slows it down so some of it soaks into the ground on my place. I'm not set up to pump from that dam. It only fills when everything is already full, so no need.