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  • Dry Conditions expected to persist for the Missouri River Basin

    The 2021 calendar year runoff summation for the Missouri River basin above Sioux City, Iowa was 15.2 million acre-feet, 59% of average. The ongoing drought shows no relief in sight and the U.S. Army Corps of Engineers is predicting runoff into the mainstem reservoir system will remain below normal. This was the 10th lowest annual runoff for the Missouri River Basin in 123 years of record-keeping.

  • Gavins Point Dam releases reduced to winter release rate

    The U.S. Army Corps of Engineers began reducing the Gavins Point releases to the winter release rate on Nov. 23, marking the end of flow support for the 2021 Missouri River navigation season. “Releases from Gavins Point Dam are being reduced to the winter release of 12,000 cubic feet per second,” said John Remus, Chief of the Missouri River Basin Water Management Division. “Releases from Gavins Point are currently 13,000 cfs and we will slowly reduce releases to 12,000 by December 8. We will closely monitor river conditions, and releases will be adjusted this winter as needed to lessen the impacts of river ice formation on stages in the lower river.”

  • Gavins Point Dam releases to be reduced in late November

    “We will continue to make releases from Gavins Point Dam to provide flow support at an intermediate service level, 1,500 cubic feet per second (cfs) less than full service, through the end of the navigation flow support season,” said John Remus, chief of the USACE, Missouri River Water Management Division.

  • Dry conditions persist in Upper Missouri River Basin; Public meetings set for Oct. 25-29

    September precipitation was once again below average in the Missouri River Basin. September runoff in the Missouri River Basin above Sioux City, Iowa (upper Basin) was 0.8 million acre-feet, 67% of the long-term average. Soil conditions in the upper Basin continue to be very dry. According to the Drought Mitigation Center, approximately 88% of the Missouri River basin is currently experiencing some form of abnormally dry conditions or drought, which is a 6% increase from the end of August.

  • USACE awards $136 million contract for Indian River Lagoon C-23 and C-24 Stormwater Treatment Area

    The U.S. Army Corps of Engineers (USACE), Jacksonville District awarded a $136,637,750.00 construction contract for the Indian River Lagoon-South (IRL-S), C-23/C-24 STA part of the Comprehensive Everglades Restoration Plan (CERP) to Kiewit Infrastructure South Co., of Sunrise, Florida.

  • Winter Gavins Point releases will be at minimum rates

    Updated: Fort Peck release reductions was incorrectly reported as Sept 6 and has been corrected to Sept. 16. Drought conditions, particularly in the Missouri River Basin above Sioux City, Iowa (upper Basin), are persisting. Per the Master Manual and the Sept. 1 System storage check, winter releases from Gavins Point Dam will be 12,000 cubic feet per second, as part of the overall water conservation measures. “Reservoir inflows in August were much lower than average. We expect below-average inflows into the System through the rest of 2021,” said John Remus, chief of the U.S. Army Corps of Engineers’ Missouri River Basin Water Management Division.

  • Drought conditions persist in the upper Missouri River Basin

    Drought conditions continue to impact the upper Missouri River Basin above Sioux City, Iowa (upper Basin). July runoff in the upper Basin was 34% of average. July runoff above Fort Peck Dam was the lowest in 123 years of record-keeping. The updated 2021 upper Basin runoff forecast is 14.6 million acre-feet (MAF), 57% of average. If realized, this runoff amount would be the 10th driest year in the upper Basin since 1898. System storage on August 1 was 53.9 MAF, 2.2 MAF below the base of the Annual Flood Control and Multiple Use Zone. System storage is expected to decline further into the Carryover Multiple Use Zone during the remainder of 2021.

  • Changes in Climate and Its Effect on Timing of Snowmelt and Intensity-Duration-Frequency Curves

    Abstract: Snow is a critical water resource for much of the U.S. and failure to ac-count for changes in climate could deleteriously impact military assets. In this study, we produced historical and future snow trends through modeling at three military sites (in Washington, Colorado, and North Dakota) and the Western U.S. For selected rivers, we performed seasonal trend analysis of discharge extremes. We calculated flood frequency curves and estimated the probability of occurrence of future annual maximum daily rainfall depths. Additionally, we generated intensity-duration-frequency curves (IDF) to find rainfall intensities at several return levels. Generally, our results showed a decreasing trend in historical and future snow duration, rain-on-snow events, and snowmelt runoff. This decreasing trend in snowpack could reduce water resources. A statistically significant increase in maximum streamflow for most rivers at the Washington and North Dakota sites occurred for several months of the year. In Colorado, only a few months indicated such an increase. Future IDF curves for Colorado and North Dakota indicated a slight increase in rainfall intensity whereas the Washington site had about a twofold increase. This increase in rainfall in-tensity could result in major flood events, demonstrating the importance of accounting for climate changes in infrastructure planning.

  • A Pulse of Mercury and Major Ions in Snowmelt Runoff from a Small Arctic Alaska Watershed

    Abstract: Atmospheric mercury (Hg) is deposited to Polar Regions during springtime atmospheric mercury depletion events (AMDEs) that require halogens and snow or ice surfaces. The fate of this Hg during and following snowmelt is largely unknown. We measured Hg, major ions, and stable water isotopes from the snowpack through the entire spring melt runoff period for two years. Our small (2.5 ha) watershed is near Barrow (now Utqiaġvik), Alaska. We measured discharge, made 10 000 snow depths, and collected over 100 samples of snow and meltwater for chemical analysis in 2008 and 2009 from the watershed snowpack and ephemeral stream channel. Our results suggest AMDE Hg complexed with Cl− or Br− may be less likely to be photochemically reduced and re-emitted to the atmosphere prior to snowmelt, and we estimate that roughly 25% of the Hg in snowmelt is attributable to AMDEs. Projected Arctic warming, with more open sea ice leads providing halogen sources that promote AMDEs, may provide enhanced Hg deposition, reduced Hg emission and, ultimately, an increase in snowpack and snowmelt runoff Hg concentrations.

  • USACE implements drought conservation measures

    Water conservation measures were enacted for the second half of the navigation flow support season based on the July 1 Missouri River Mainstem Reservoir System storage, per the guidelines outlined in the Master Manual. Very dry conditions continue to impact the upper Missouri River Basin above Sioux City, IA (upper Basin) despite recent heavy rainfall in the lower Basin. As a result of the low precipitation and widespread drought conditions, June runoff in the upper Basin was 52% of average. The updated 2021 upper Basin runoff forecast is 15.6 million acre-feet (MAF), 60% of average. If realized, this runoff amount would be the 10th driest year in the upper Basin since 1898. System storage on July 1 was 55.2 MAF, 0.9 MAF below the base of the Annual Flood Control and Multiple Use Zone. System storage is expected to decline further into the Carryover Multiple Use Zone during the remainder of 2021.