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Folsom Lake Level Discussion - Mormon Island Exposed

yes its officially drought

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#106 chris v

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Posted 07 January 2014 - 08:43 AM

 

The Natomas Ditch actually ran well east of the school.  Here is a current Google Map overlayed with a 1948 topo map.  The green line is the wall as recorded with my GPS.

MormonIslandmap.jpg

 

Here is the topo map only for clarity.

MormonIslandmap2.jpg

 

 

no, those are mining tailings.  just conferred with the archaeologists in our office.  the retaining wall is slightly off in this GIS layer.  It actually held back the road in that area and was very likely related to the dam construction effort in the 1940s.  Also, that last photo by Chris V is a great one showing the actual area known as Salmon Falls.  That is the falls, not the area upstream that we associated with it. 

 

 

I was down there yesterday afternoon and I believe you are both right.  That wall definitely held back wetlands.  Remember before the dyke was built things looked a lot different.  If you look at the elevations on the old map of the wetlands across Green Valley Rd and the ones near the Mormon Island School, they are roughly the same.  Essentially making that whole area the same wetlands.  The current elevation of the area behind the wall has been backfilled with tailings of some sort for a road at one point in time.  Either way, there has been a lot of backfilling and material moving in that area over the years.  I believe it was originally built to hold the wetlands back but over time was used for a road. 



#107 chris v

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Posted 07 January 2014 - 09:59 AM

And some more pictures from yesterday.

 

IMG_3370_zpsfc0becf4.jpg

 

IMG_3371_zpsbe0090fa.jpg

 

IMG_3373_zps827a8ccf.jpg

 

We found this hole, that was about 8-10 feet deep, it was kind of cave like from what I could see.  I don't know how far it goes in any direction but I couldn't really see in too far as I didn't want to get too close to it.

 

IMG_3376_zpsa0528987.jpg

 

The wall as discussed earlier

 

IMG_3378_zps7a2afd22.jpg

 

IMG_3379_zps2015954a.jpg

 

IMG_3380_zps64a05991.jpg

 

And of course, the Mormon Island School is making a quick appearance.

 

IMG_3382_zpsc0d97f30.jpg



#108 4thgenFolsomite

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Posted 07 January 2014 - 10:14 AM

that wall is definately the downslope wall of a roadway.  you can't hold back a wetland with a retaining wall. 

great photos.


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#109 chris v

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Posted 07 January 2014 - 11:03 AM

that wall is definately the downslope wall of a roadway.  you can't hold back a wetland with a retaining wall. 

great photos.

 

I completely disagree.  What does the dam do?  Holds back wetlands.



#110 4thgenFolsomite

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Posted 07 January 2014 - 12:24 PM

 

I completely disagree.  What does the dam do?  Holds back wetlands.

a dam holds back water.  wetlands are wet land.  water moves in the ground.  a retaining wall is not going to stop the flow of water in the ground itself. 


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#111 mrdavex

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Posted 07 January 2014 - 04:41 PM

a dam holds back water.  wetlands are wet land.  water moves in the ground.  a retaining wall is not going to stop the flow of water in the ground itself. 

 

Despite the best construction of a dam, water will still flow under it: http://www.damsafety...30-067140346bb2

 

The headwaters of Willow Creek are from seepage under the Mormon Island Dam.  There is also seepage under all the Sacramento River levees.  There are several sump pump stations along the land side of the levees that collect seepage and return it back to the river.  If seepage is not evacuated via natural or artifical means, the water table rises and then the dam or levee catastrophically fails.

 

Due to the banked construction of a dam or levee (much thicker at the bottom than top), it does a much better job at holding all the water back, as opposed to a straight retaining wall.  That retaining wall in Chris V's excellent pic looks like it was built with more modern construction techniques; looks like it's cast-in-place or pre-cast concrete block.  I cannot guess on what purpose it serves, but unless it has some type of waterproofing on the dirt side, grounwater will seep through it.


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#112 4thgenFolsomite

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Posted 07 January 2014 - 06:43 PM

 

Despite the best construction of a dam, water will still flow under it: http://www.damsafety...30-067140346bb2

 

The headwaters of Willow Creek are from seepage under the Mormon Island Dam.  There is also seepage under all the Sacramento River levees.  There are several sump pump stations along the land side of the levees that collect seepage and return it back to the river.  If seepage is not evacuated via natural or artifical means, the water table rises and then the dam or levee catastrophically fails.

 

Due to the banked construction of a dam or levee (much thicker at the bottom than top), it does a much better job at holding all the water back, as opposed to a straight retaining wall.  That retaining wall in Chris V's excellent pic looks like it was built with more modern construction techniques; looks like it's cast-in-place or pre-cast concrete block.  I cannot guess on what purpose it serves, but unless it has some type of waterproofing on the dirt side, grounwater will seep through it.

exactly. 


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#113 Steve Heard

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Posted 08 January 2014 - 03:13 PM

With the threat of a drought, even water-rationing looming, the California Catholic Conference of Bishops is calling on people of all faiths to pray for rain.

 

Coincidentally, MyFolsom's own Dawn Grove organized a rain ceremony this past Sunday at Folsom Lake.

 

I'll let Dawn tell the story:

 

It was eight in the morning on a cold Sunday in January; the sky was pale blue and depressingly clear. Not a cloud in sight. There were fifteen of us representing various races, genders, economic backgrounds, ranging from age two to sixty-five. Many of us were friends, some had not met each other before, but all of us were affected by and concerned about the drought.  We were here to call the rains.

We danced the zigzag pattern of the water. We chanted to call the rain, we chanted to call the Spirit of the West to bring them. We made a solemn pledge to honor our Mother Earth and Father Sky. We tied blue ribbons and pinned them to our clothes to make a bond, a promise, to be aware of the precious gift of water and to conserve and use it responsibly.

After the ceremony we hiked the desolate landscape. It was a solemn reminder at first but then we began to talk and laugh. We spent two hours exploring the ruins, taking pictures and looking at the artifacts that folks had placed on stumps and broken walls for us to find (it is illegal to remove anything from the park). We laughed as we helped each other jump the stream and worked as a unit helping a big wheeled stroller over. We joked with strangers and petted dogs and placed our own found artifacts on stumps.

When it was time to leave, we all somehow found each other even though our hike had scattered us for a couple of miles. Without a word or any preset plan we gathered and walked out together. As we neared our cars, we gathered for a group photo and then hugged each other, bonded. We all grinned and many of the participants exclaimed how beautiful the ceremony was.  Two women who were strangers before the ceremony left together to get lunch.  As friends, they drove away in a convertible; they were chatting and laughing.

The ceremony was not about superstition but about comforting each other. It was about a community coming together to support each other and to channel their concern into something positive. Rain did not immediately begin to fall on our heads but we received a gift almost as good; friendship and hope.

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But rather how well its people have learned to relate to their environment and fellow man.”
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#114 Silverado

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Posted 08 January 2014 - 06:33 PM



that wall is definately the downslope wall of a roadway.  you can't hold back a wetland with a retaining wall. 

great photos.

 

The roadway apprears at the base of the wall.

IMG_1314.jpg


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#115 caligirlz

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Posted 08 January 2014 - 08:09 PM

Steve, thanks for posting about Dawn's rain ceremony. But now I can't "like" her post!

#116 Johnjohn

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Posted 09 January 2014 - 11:37 AM

Wow the lake is low.  i have been doing some mapping of the bottom of the lake.  using the topo maps from 1892 and 1941 i think i have located the actual town of mormon island. I wish google had a current sat map of the area with the water so far down.   from what i have seen in the topo maps they are accurate to about 100 yards.  I really have my doubts that mormon island is even visible with the lake dry due to it being so close to the spillway project.  it may be covered up by rock and gravel. There should be a bridge on the west side of Mormon Island according to the map. It also looks like the school was placed up the hill about 1/2mi east of the town.

According to topo maps the town should sit around 275 to 300ft elevation and the lake is currently at 360.  the school sits at about 365ft.



 

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#117 chris v

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Posted 09 January 2014 - 12:34 PM

Wow the lake is low.  i have been doing some mapping of the bottom of the lake.  using the topo maps from 1892 and 1941 i think i have located the actual town of mormon island. I wish google had a current sat map of the area with the water so far down.   from what i have seen in the topo maps they are accurate to about 100 yards.  I really have my doubts that mormon island is even visible with the lake dry due to it being so close to the spillway project.  it may be covered up by rock and gravel. There should be a bridge on the west side of Mormon Island according to the map. It also looks like the school was placed up the hill about 1/2mi east of the town.
According to topo maps the town should sit around 275 to 300ft elevation and the lake is currently at 360.  the school sits at about 365ft.



 


My last picture shows the Mormon Island school foundation coming out of the water.

#118 4thgenFolsomite

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Posted 09 January 2014 - 12:48 PM

Chris, the archaeologists in the office are curious about that wall now.  We see the road at the base of it, you are right.  But doubt the function of that wall still.  the chamfered corners on the buttresses seem too finished for dam construction work, but possibly something to do with either a materials stock pile or loading dock. 

 

I understand State Parks is keeping an archaeologist stationed out there now during open hours to answer questions and monitor activity around the artifacts.


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#119 Johnjohn

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Posted 09 January 2014 - 02:27 PM

yes good picture of the school. i used its location and the water level to nail down the accuracy of the topo maps.



#120 Johnjohn

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Posted 09 January 2014 - 02:57 PM

i just found this.  Jason Bross shot this with an aerial quadcopter Great Vid!

http://www.youtube.c...BG8t7Yo0Y#t=250


EDIT:   adding some more credit for the person who shot the vid.  here is his webpage/business http://www.airshotz.com/






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