BLACKFOOT — It was Saturday, June 5, 1976.

I was sitting at my desk early on a Saturday morning paying bills when I learned that the newly built Teton Dam in southeast Idaho had collapsed. I immediately turned on my citizens band radio to see if anyone else in the Blackfoot area had heard the news.

I was president of the “Dirtyfoot CB Club” and my younger brother Lee Mangum was president of the “Blackfoot Emergency CB Club.” Between the two clubs, there were nearly 300 members scattered from north of Idaho Falls to south of Pocatello. Most of them wanted to rush right out and go to Rexburg and try and help. The decision was made that by the time we went north, it would be too late to be of much help. Some of them went up anyway to help friends and relatives.

Several of us were volunteer firemen so we went to the Fire Department/ Police Station to assist Disaster Services Director Eddy Barrus, Fire Chief J.T. Swartz, Police Chief Knobby Taylor, or whomever we could by delivering messages or running errands.

We started out by going to the houses that had been built in the “low areas” near the Snake River that runs along the western edge of the city limits. We walked through the Parkway trailer court and the area at the golf course, knocking on doors and alerting residents of the potential flooding problems.

Nearly all of Parkway Trailer court is built in an area that had high water sloughs back in the days before the Palisades Dam was built in the 1950s. We advised them to pack a suitcase and anything they didn’t want to get wet and be ready to move out as soon as the high water reached Blackfoot. Nearly everyone was cooperative and thanked us for alerting them to the danger.

Not everyone was excited about leaving the area for dry ground. In Blackfoot when Interstate 15 was built, some of the gravel was removed from the riverbed at a place where the Snake River was being straightened out to eliminate building another bridge. After the freeway was built, this gravel pit became the Jensen Grove Lake and part of the city’s parks.

On this beautiful Saturday afternoon, several water ski enthusiasts were there playing around in the water. I advised them about the Teton Dam breaking and told them they needed to leave. They told me they had a boat and all the beer they could drink so they didn’t think they needed to leave. When I asked them how many lived in the low areas along the river or had family or friends that did, they changed their minds and went home.

Since the collapse of the Teton Dam could and would bring high water and the danger of flooding to Bingham County and towns along the banks of the Snake River, the Emergency Operations Center was activated. The Blackfoot Police and the Sheriff’s Office called in the Search and Rescue and Jeep Patrol to help man the radios and become roving eyes and ears along the river. These operators would also be able to relay requests to the Road and Bridge departments for sand and gravel as well as being a hub for any other request for any needed supplies.

The CB radio can be a useful tool in emergencies. Lee and I and several others in the area volunteered to assist by manning some checkpoints and providing radio contact as best we could. We set up a CB base station in the room next to the E.O.C. in the basement of the police/fire building and relayed information across the hall. We also set up the Dirtyfoot CBers Club trailer behind the fire station to use as a sandwich and coffee stop for any of the emergency personnel. They would both be in continuous operation for the next five days.


Sunday morning brought some semblance of order to the excitement. Sheriffs departments, city police, as well as street, road and bridge crews up and down the valley were on alert. That was about the time the news showed one of the houses floating down Main Street in Rexburg. But Idaho Falls was able, with the help of thousands of volunteers, to fill and place enough sandbags along the riverbanks to keep the water from flowing out into the homes and business locations within the city limits along the river.

Lee was working at the Atomic Energy Commission site for the Department of Energy. He was called out to work so that the equipment operators could be available to help protect some of the business offices and warehouses in Idaho Falls. Those volunteers along both sides of the river above the Broadway Bridge near the falls were standing in water above their waist, while passing sandbags hand over hand along the riverbank. He was gone from Blackfoot for nearly seven days.


Most of us had jobs where we had to show up for work. I worked for American Potato at a building near the Post Office and behind the Elks Lodge in Blackfoot. Most of the conversation that Monday was about when and where the high water would arrive.

When it looked like the main processing plant at American Potato would be flooded, they let those employees not needed to secure or shut down the plant go home so they could help friends, family, or neighbors prepare for the flood. We were off work for the rest of the week.

Between Idaho Falls and Blackfoot there are about a dozen irrigation canals that under normal conditions transfer water from the Snake River through the countryside. This water provides nourishment to several hundred square miles of farm crops. Some of these canals are dozens of miles in length. The Aberdeen/Springfield Canal system has nearly 350 miles of ditches and laterals. It starts diverting river water from just west of Firth and ends approximately 60 miles south in Aberdeen.

These canal companies could see the writing on the wall, that if they couldn’t keep the floodwater out of those long waterways there would be water damage occurring several miles away from the main river channel.


My father, Guy R. Mangum was the watermaster for the Riverside Ditch Co. It diverts water from the Snake River about 10 miles north of Blackfoot and provides irrigation on the west side of the river down through the Groveland town site and even as far west as Moreland. The upper headgates for this canal are in the vicinity of the old Lavaside School Building about halfway between the Rose Exit on the freeway and Firth. He knew that the main headgates on the river would be almost impossible to protect but perhaps the secondary control headgates downstream might be saved. My dad called me on Monday night to see if I could come help him provide some protection to those huge control gates. The decision was made to close the first set of gates and hope for the best.

The secondary control headgates are located within a quarter of a mile east of the Rose Exit on Interstate 15. These headgates were also closed. Dad called T.J. Patterson to bring his backhoe and dump truck to load and haul material to cover the headgates and bridge. T.J. ran the loader and I drove the dump truck. The gravel for this project was removed from one of the high spots just below the lower headgates.

While we were hauling gravel to fill the canal, some volunteers arrived with a couple hundred sacks of sand to fill in wherever needed. We never did get to thank them but the license plates on those overloaded pickups were from Bannock County.

When we started that morning the water level in the river was about normal with several feet of riverbank still visible above the water that was probably five or six feet below the last high water marks. By around 10 a.m. there was a noticeable rise in the amount of water going past in the river. This was probably due to all the canals shutting off their headgates and not from the floodwater. I believe it was around 1 p.m. when we noticed the first water coming up over the riverbanks and starting to fill those old high water sloughs and auxiliary channels.

We moved enough gravel to completely cover the headgates both front and rear as well as the bridge. This made a gravel dam about 20 feet thick, about 14 feet deep, and over 25 feet long.

After the lower headgates on the Riverside Canal were covered with gravel and the canal was filled in, it appeared that we had been successful in keeping the flood water from racing down its channel and creating problems down the line in the Groveland area. However the Snake River, which in the past couple of hours had risen to the high water marks and above, was seeking to flow through the low areas and did in fact find a low place in the canal bank. It quickly cut through the gravel canal bank about a quarter of a mile behind the headgates and started to refill the canal we had worked so hard to drain.

The decision was made to move down the canal a couple of miles to a location where the canal is just over 100 yards from the river but it is probably four or five feet above the normal river water level. On the way down the road to the location near the Porterville Bridge, we crossed over Interstate 15, between the Rose Church house and the Porterville Bridge.

The water was already flooding across the river bottoms in the area where the archery range is now. It was just starting to flow under the fence on the east side of the freeway and headed towards the overpass footings. The water would eventually cover both the north and southbound lanes of the freeway.

As the sun was setting that night on the Snake River, the water level was starting to push out onto some of the low roads and fields along the banks. But by noon the next day, it would be higher still.

As the water in the river started to creep up on the high water marks, residents living in the low areas or places that could be flooded if the water came over or through the river banks started to call for sandbags. Some members of the Blackfoot Emergency CB Club and the Dirtyfoot CBers were sent to several locations where the county and city dump trucks hauled sand to be put in bags. Volunteers by the hundreds showed up with shovels and buckets and willing hands to hold the empty potato sacks to be filled. It didn’t take very long until the word came back from the places where the sand bags were delivered, “Don’t fill them so full!”

There were several times when the sacks were being filled faster than they could be tied shut. The truck loads of sand would disappear almost as fast as the trucks could haul it in. And several times the shovelers had to wait for more empty bags. The Club members helped the EOC send the filled sacks to where they were requested or needed. Hundreds of pickup trucks would be transferring sandbags like ants scurrying around to rebuild their nest and dozens more were lined up waiting to get reloaded.

Out at American Potato’s main plant and offices, they had a couple of D-8 Cat dozers unloaded and sitting in the parking lot. My good friend Danny “Corky” Johnson was operating one of them. He told me that when the water started getting close, the order was given to make a berm around the offices and warehouse. They pushed up the parking lot, lawn, sidewalks, grass and asphalt and all.

After helping T.J Paterson and my dad all day with the efforts to protect the Riverside Canal, I headed to town. That evening as the water began to crowd out in the trees and low areas, it tried to find its way back down some of those old high water channels and sloughs. One of these places was just north of the Blackfoot Golf Course on the east side of the river. The Corps of Engineers and the State Highway Department had built a dike along this area to turn the river underneath the twin bridges on the freeway. I doubt if anyone could even make a guess at how many sandbags and loads of gravel were hauled into this area before and during the time that the river finally won out over all the efforts to contain the water.

When the water broke through this area, it was then free to flow across the golf course and the airport. Any water then was forced out into the houses down below Kesler’s Market and along Parkway Drive. Even though it had not made reservations, the water filled every one of the rooms on the ground floor of the Riverside Inn. After filling in the area where the Jenkins dealership now stands, it continued south across the highway into town and started to fill up the Riverside Plaza.

After the water drained off and the public was let back in to the Plaza, I could see a high water mark on the bank building in the northwest corner of the parking lot approximately 1 1/2 feet below the ceiling on the first floor. Even with all of the efforts to build a sandbag dike to protect them, all of the buildings in the plaza were flooded including the Albertson’s grocery store.


After the high water started to recede, the water damage started to show up. Local residents attempted to reach their homes and business locations that had been under water only 24 hours before. The local canals began assessing the damage and trying to provide irrigation water for all those farms up on high ground. One of the canal companies on the east side of the river had to completely rebuild its headgate system before they could control the water. The Riverside Canal Co. was very fortunate because there had not been much water damage below the location where the channel had been made near the Porterville Bridge.

The first thing on Thursday morning my dad started to work. He had T.J. Patterson bring his backhoe and dump truck and a small dozer tractor back out to the headgates in Rose. Lynn and I went along to help as needed. It took several hours to dig the gravel bar out from in front of the headgates and uncover the bridge. The place where the water ran over the bank and back into the canal wasn’t washed away too bad and the bank was still high enough to contain the canal water from running out.

At the control check and headgates just below the Wareing milk barn and corrals, the water had washed part of the canal bank away. We hauled some lava rocks from the quarry out on the north end of the McDonaldville road over to build up the bank and covered them with dirt.

As we drove back over the freeway overpass, we could see where the water had washed away part of the roadway and the riverbank. Any low places still had water standing in them. The gravel pits between the freeway and the river were still brimful and during the next few years became a great place to fish.

It was just after noon on Friday when we opened the headgates and let the water back down the canal. The Riverside was the first canal back in service. I believe that no actual flooding occurred in the canal service areas that weren’t flooded by water directly from the river. Most of the other canals were not so fortunate. Many areas and locations away from the river were flooded and sustained some severe damage because of the water flowing down the canals.

It took nearly two weeks for a couple of the canals to get back in service.