BOARD00100 - Laserfiche WebLink

Home Browse Search

because we are never taking conservation space. ~le are simply going up into that remaining 278,000 feet of space. The perma- nent pool rides on top of that space, It doesn't make any difference how much it silts in. until, of course, it silts in com- pletely,which is anbther hundred years at least. None of us will be around to see that. I Our engineers have prepared a profile showing siltation which has occurred in John ~~rtin Reservoir so that we could graphi- cally portray the situation as'it has actually occurred. Over here we have eleva- tions above mean sea level. The top of the present conservation pool is authorized at 3851 feet above sea level. That means that when the reservoir is full, water would be up to this point. Back up the river this far (that's about l4t miles upstream) this will all be water. Here is a profile of the sediment. This heavy line is the origin- al stream channel before John r~rtin.was placed in operation. You can see how the siltation has occurred. There is apparently some feeling that this siltation occurs in a flat bed and fills up. the basin evenly. That being the case it would finally flatten out any permanent pool until it was just a shallow bit of water. Now again that's not true. You will notice at: the upper end of the river actually a scour has occurred. That is within the reservoir bed. The scour has occurred at. this point. From there on then, you drop down again to the stream bed and then siltation occurs in an irregular pat- tern but, generally, the heavy siltation occurs in the area several miles above the face of the dam. At the face of the dam there is a sharp drop in the silt pattern. Also at the face of the dam the water is considerably deeper than it is back upstream. Now we get back to depth, which is a factor contributing to the success bf fish. With a 10,000 foot permanent pool, when this reservoir would otherwise be dry, the depth of the water at the face of the dam is 21.6 I