The Palisades Dam was built 1951-57 at an estimated cost approved at $71-91 million. I remember going up to the dam site when I was a little boy and watching the amazing construction. Now there is a 'reported' water shortage and aquifer depletion and the Idaho Water Resource Board (IWRB) is considering the options.
One of those options, raising the Island Park Reservoir, has created a monster worry problem for shoreline homeowners. Raising Palisades Reservoir has not been studied. Palisades is about ten times larger than the Island Park Reservoir and is not surrounded by lake homes. Deeper than the Island Park Reservoir, Palisades has a surface area 2.3 times greater than the Island Park Reservoir, meaning that raising Palisades by one foot generates 2.3 times the water storage compared to raising the Island Park Reservoir by one foot. Quietly studying the Island Park Reservoir for the past ten years, the Idaho Department of Water Resources (IDWR) first announced their impact estimates to personal property of up to $70 million at a public meeting in Rexburg, July 24, 2019. Prioritized options for the Henry's Fork Basin were reviewed. Rebuilding the Teton Dam was last option on the list and was discounted as being too unpopular. The IDWR website has the slide presentation for review. Sophisticated engineering measurements estimating the actual effects of raising the Island Park Reservoir have shown that raising it would result in significant property damage to many shoreline homes. The final engineering report over the LIDAR study are complete, not yet released to the public. The initial report indicated estimated costs of 'wetted basements' from flooding to be about the same as the original cost to build the Palisades Dam. Incremental damage associated with one to four foot elevations in the Island Park Reservoir level are being examined and an expensive feasibility study is being considered by the Idaho Water Resource Board.
Neither The Bureau of Reclamation nor the IDWR has studied raising the Palisades Reservoir. A verbal report to me is that this is because of low lying Alpine,WY and the potential for flooding. Alpine is located at the south end of the reservoir and sits at the confluence of the Salt River, Greys River and Snake River. Alpine is subject to some spring flooding from the Salt and Greys Rivers when the runoff is high. At times with high flow and runoff, the level of the confluent rivers at the south end of Palisades Reservoir can be 1 foot higher than the level of the reservoir at the dam, 25 miles to the north. Does Alpine have occasional spring flooding due to the level of the reservoir or is it the rivers that occasionally flood Alpine? As opposed to raising the Island Park Reservoir, studies and sophisticated measurements are absent when it comes to Palisades. Ever vigilant, and as an Island Park Reservoir shoreline homeowner, I decided to do an initial, private study on the Palisades Reservoir and referred to the published website data on elevations with the following results: Palisades reservoir highest surface level: 5620 ft (5623 ft on one topographical map) Aline, WY with variable elevations from 5633 to 5659 ft. (Listed as 5672 ft on the Wyoming Webpage) Calamity Campground on the shore of Palisades Reservoir: 5700 ft Using these elevations, the lowest reported elevation at Alpine WY is 10-13 feet above the surface level of the Palisades Reservoir. Palisades filled surface area is 16,100 acres/25 square miles and the storage is estimated at 1.2 M acre ft. The Island Park Reservoir has a filled surface area of about 7000-8000 acres/11 square miles with a storage capacity of 135,205 acre feet. Being deeper, Palisades has 8.875 times the water storage of the Island Park Reservoir. The surface area comparison is a ratio of 16,000/7000 or 2.3. Raising the filled level of Palisades Reservoir 1 ft would be equivalent to raising the filled level of the Island Park Reservoir 2.3 feet. At 2 ft, the elevation at Island Park would need to be 4.6 ft. A Palisades Reservoir elevation of 4 ft, would need an Island Park Reservoir elevation of 9.2 ft to achieve an equivalent amount to help solve the water shortage. From my perspective, raising the elevation of the Palisades Reservoir offers a greater resulting volume of water storage by a factor of 2.3 to 1. I learned my math in Rigby, so you may want to double check my calculations or use your own internet resources. It just seems to me that a 2.3 to 1 advantage is significant. This 2.3 to 1 advantage should be carefully compared to the other options before proceeding with an expensive feasibility study of Island Park Reservoir. Granted, Palisades is not in the Henry's Fork Watershed Study. However, Idaho tax dollars would be needed to fuel either project. In addition to raising Palisades, other options include dredging the Island Park Reservoir, re-engineering and rebuilding the Teton Dam, and/or diverting part of the Snake River during times of high runoff into the aquifer. My patients in the New Sweden irrigation district tell me that they have watched as water runs out onto the lavas and just disappears. I think that they are right. If recharging the aquifer is a goal, diverting some of the spring runoff directly into the aquifer seems to be a logical solution. For $70M you could get a lot of dredging and diverting, rather than use the same amount of money to pay for flooded-property damage to a whole herd of angry-as-hornet homeowners. When you grow up in Rigby, you learn early in life why it is not a good idea to throw cow pies at a hornet's nest, again. Hurl a dried up cow pie at the hornet's nest rapidly becomes a really good lesson that you never forget. Doing that twice is just stupid. Hornets fly in ever enlarging circles and catch you again and again as you run in a straight line away from them. I did not know that. My grandfather, William Tall, used to be the Delco-Light dealer in Rigby. He would install the Delco-Light system for rural and farm home lighting for Jefferson and rural Bonneville Counties. When electric power was provided more and more by overhead lines, he went out of business and opened the first Conoco station in Rigby. Although he had an eighth grade education, he was fairly high tech for his time with Delco-Light and Conoco. His last Delco-Light customers were from Irwin, the community that still sits below the Palisades Dam. Above the dam, the road from Irwin to Alpine WY went down the 'Grand Valley'. That road was bordered on one side with poles, transmitting electric power and telephone lines. These poles were not removed when the Palisades Reservoir was filled and still stand, under over 100' of water next to the old roadway that becomes visible when the reservoir is drawn down during a poor water year. Those poles are a form of memorial to my grandfather's Delco-Light business because when the power poles went up, he no longer was in the Delco-Light business. To some degree it was a relief because the Delco-Light service calls involved fiddling with bottles of carbonic acid and gas and getting electrical shocks. My grandfather recalled being particularly annoyed by the Farnsworths, whose son frequently broke the system, doing experiments. You may have heard of him----Philo T. Farnsworth, the inventor of television, who also learned his math in Rigby.
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