Originally published on May 10, 2011 in the Minot Daily News
Click here for original link.
by Kim Fundingsland
(blogmaster's note: for a more downstream perspective, check out this link from the Omaha World-Herald: http://www.omaha.com/article/20110507/NEWS01/705079838/-1)
RIVERDALE - The numbers are nothing short of staggering. In a spring where there seems to be too much water in virtually every drainage system, why should the largest reservoir in the Missouri River system be left out? The answer is, it won't be.
The volume of water expected to enter the Yellowstone and Missouri Rivers and, eventually Lake Sakakawea, will almost certainly flow right through the record books. Even with a record amount of snowfall still sitting in the mountains of Montana, and Lake Sakakawea sitting several feet higher than it was a year ago, another major storm is poised to impact Montana and further influence a massive runoff.
A National Weather Service hydrologist very near the situation warns of the possibility of "sensational" runoff, all while Montanans were under a warning Monday to prepare for a dump of two feet of snow in higher elevations and two to four inches of rain elsewhere. Following one of the wettest fall seasons ever and a winter of record snowfall, many wonder if summer will ever arrive. It might be best if it doesn't.
Gina Loss, NWS hydrologist in Great Falls, Mont., said only an unseasonably cool spring has kept a record runoff at bay. In the meantime the mountain snowpack has continued to accummulate at an alarming rate. Eventually deep snows will give way to warmer temperatures.
"We are two to three weeks past when we should have had a snowmelt," said Loss. "We really haven't started losing that much snow and it just keeps coming. That means there's a lot of water to get out in a shorter amount of time. That snowpack has really been holding tight."
Much of Montana's snowmelt will enter the Missouri and Yellowstone River basins. As of May 1 the water content of the Montana snowpack that will drain into the Missouri was listed at 141 percent of normal by the U.S. Army Corps of Engineers. The Yellowstone drainage is listed at 136 percent of normal.
"Those are two we are watching really closely. It's been a real unusual winter for us, packing snowmelt runoff into what may be a much shorter window of time," said Loss.
If the Corps' May runoff outlook for the entire Missouri River Basin proves true, 178 percent of normal and 44 million acre feet of water, it will be the second-largest runoff for the system since record keeping began in 1898.
"At a time when we thought the snowpack would be peaking, it continues to increase," said Jody Farhat, of the Corps' office at Omaha, Neb. "The record was 49 million acre feet in 1997, but this is much higher than normal. We still have room in some reservoirs, but if there is a major flood event on the lower reaches of the river we will cut back. The difference this year is, we don't have a lot of room. We just have to use our storage very judiciously."
Reaction to the massive buildup of snow and threatening forecast has been felt at all six Missouri River reservoirs where the amount of water being released has been dramatically increased.
"What it amounts to is evacuating storage, but that uses up channel capacity all the way down to the Mississippi," explained Farhat. "These releases alone won't cause flooding but, with less channel capacity and rainfall events, water stages in places could be very high."
Releases from the system's largest storage facility, Lake Sakakawea, have been significantly increased and will continue to rise. Monday's release was 42,000 cubic feet per second and, based on the latest forecasts, will be ramped up until reaching 49,000 cfs by Friday at the latest.
"We're running as much as we can through the turbines right now," said Todd Lindquist, Corps project manager at Riverdale. "Normally we utilize five but we're doing a major rehab on one, so there's only four running with about 30,000 cfs going through the plant. Anything above that is passing through the regulating tunnels. We'll let the river stabilize and make sure we're not causing any other issues before we go all the way to 49,000 cfs."
Already the surge of water through the three regulating tunnels at Garrison Dam has led to the closing of the wingwall fishing area in the interest of public safety. The frothy, churning water adds a noisy and eerie effect to the Tailrace where water levels are on the increase. It is the first time water has flowed through the tunnels since 1997. As far downstream as Bismarck the level of the Missouri is expected to be 5 feet higher than it was about one month ago.
With the possibility of so much water remaining to enter the system, the high releases are scheduled to be maintained at least until the end of July. It is an astonishing amount of water to move downstream.
To put the numbers in perspective, the previous maximum outflow in May from Garrison Dam was 41,200 cfs in 1997. May's historic average outflow is 20.7 maf. Looking ahead to June, when 49,000 cfs is expected to be released for the entire month, the historic average is only 22.6 maf. Clearly, what is occurring all along the Missouri River is already a record-breaking event and it is just getting under way.
"49,000 is what our Management Division has determined we need to move through Garrison," explained Lindquist. "They are trying to balance the impact through all the reservoirs. All are passing additional water. It's definitely a wet year."
Lake Sakakawea was at 1848.2 feet Monday. That compares to 1838.9 feet at the end of April 2010. Inflow to the reservoir is expected to surpass the 49,000 cfs outflow later this month.
According to the Corps, Lake Sakakawea's "exclusive flood zone" is from 1,850 to 1,854 feet, the latter being the height of the top of the spillway gates. The latest projection, which is subject to revision depending on the rate of snowmelt and other weather events, has Lake Sakakawea topping out a slightly over 1,852 in late July.
The volume of water expected to enter the Yellowstone and Missouri Rivers and, eventually Lake Sakakawea, will almost certainly flow right through the record books. Even with a record amount of snowfall still sitting in the mountains of Montana, and Lake Sakakawea sitting several feet higher than it was a year ago, another major storm is poised to impact Montana and further influence a massive runoff.
A National Weather Service hydrologist very near the situation warns of the possibility of "sensational" runoff, all while Montanans were under a warning Monday to prepare for a dump of two feet of snow in higher elevations and two to four inches of rain elsewhere. Following one of the wettest fall seasons ever and a winter of record snowfall, many wonder if summer will ever arrive. It might be best if it doesn't.
Gina Loss, NWS hydrologist in Great Falls, Mont., said only an unseasonably cool spring has kept a record runoff at bay. In the meantime the mountain snowpack has continued to accummulate at an alarming rate. Eventually deep snows will give way to warmer temperatures.
"We are two to three weeks past when we should have had a snowmelt," said Loss. "We really haven't started losing that much snow and it just keeps coming. That means there's a lot of water to get out in a shorter amount of time. That snowpack has really been holding tight."
Much of Montana's snowmelt will enter the Missouri and Yellowstone River basins. As of May 1 the water content of the Montana snowpack that will drain into the Missouri was listed at 141 percent of normal by the U.S. Army Corps of Engineers. The Yellowstone drainage is listed at 136 percent of normal.
"Those are two we are watching really closely. It's been a real unusual winter for us, packing snowmelt runoff into what may be a much shorter window of time," said Loss.
If the Corps' May runoff outlook for the entire Missouri River Basin proves true, 178 percent of normal and 44 million acre feet of water, it will be the second-largest runoff for the system since record keeping began in 1898.
"At a time when we thought the snowpack would be peaking, it continues to increase," said Jody Farhat, of the Corps' office at Omaha, Neb. "The record was 49 million acre feet in 1997, but this is much higher than normal. We still have room in some reservoirs, but if there is a major flood event on the lower reaches of the river we will cut back. The difference this year is, we don't have a lot of room. We just have to use our storage very judiciously."
Reaction to the massive buildup of snow and threatening forecast has been felt at all six Missouri River reservoirs where the amount of water being released has been dramatically increased.
"What it amounts to is evacuating storage, but that uses up channel capacity all the way down to the Mississippi," explained Farhat. "These releases alone won't cause flooding but, with less channel capacity and rainfall events, water stages in places could be very high."
Releases from the system's largest storage facility, Lake Sakakawea, have been significantly increased and will continue to rise. Monday's release was 42,000 cubic feet per second and, based on the latest forecasts, will be ramped up until reaching 49,000 cfs by Friday at the latest.
"We're running as much as we can through the turbines right now," said Todd Lindquist, Corps project manager at Riverdale. "Normally we utilize five but we're doing a major rehab on one, so there's only four running with about 30,000 cfs going through the plant. Anything above that is passing through the regulating tunnels. We'll let the river stabilize and make sure we're not causing any other issues before we go all the way to 49,000 cfs."
Already the surge of water through the three regulating tunnels at Garrison Dam has led to the closing of the wingwall fishing area in the interest of public safety. The frothy, churning water adds a noisy and eerie effect to the Tailrace where water levels are on the increase. It is the first time water has flowed through the tunnels since 1997. As far downstream as Bismarck the level of the Missouri is expected to be 5 feet higher than it was about one month ago.
With the possibility of so much water remaining to enter the system, the high releases are scheduled to be maintained at least until the end of July. It is an astonishing amount of water to move downstream.
To put the numbers in perspective, the previous maximum outflow in May from Garrison Dam was 41,200 cfs in 1997. May's historic average outflow is 20.7 maf. Looking ahead to June, when 49,000 cfs is expected to be released for the entire month, the historic average is only 22.6 maf. Clearly, what is occurring all along the Missouri River is already a record-breaking event and it is just getting under way.
"49,000 is what our Management Division has determined we need to move through Garrison," explained Lindquist. "They are trying to balance the impact through all the reservoirs. All are passing additional water. It's definitely a wet year."
Lake Sakakawea was at 1848.2 feet Monday. That compares to 1838.9 feet at the end of April 2010. Inflow to the reservoir is expected to surpass the 49,000 cfs outflow later this month.
According to the Corps, Lake Sakakawea's "exclusive flood zone" is from 1,850 to 1,854 feet, the latter being the height of the top of the spillway gates. The latest projection, which is subject to revision depending on the rate of snowmelt and other weather events, has Lake Sakakawea topping out a slightly over 1,852 in late July.
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