Notice to Navigators: Lower Mississippi River
Lower Mississippi River (LMR) Dredging Update 51121
The U.S. Army Corps of Engineers (USACE) has now completed the Phase 1 dredging for the historic project to deepen the Mississippi River Ship Channel (MRSC) to 50 feet. The Phase 1 section of the Ship Channel extends from Venice at Mile 13 Above Head of Passes (AHP) to Mile 22 Below Head of Passes (BHP). However, the USACE has uncovered some anomalies with pipelines crossing under the Ship Channel in the area of Venice, mainly between Mile 12 AHP and Mile 11 AHP. Due to the information uncovered the USACE is reaching out to pipeline owners in the area to verify the depth over the pipelines in this corridor before the Ship Channel can officially be opened to a deepened draft (50 Feet).
This afternoon the Crescent Pilots increased their maximum draft recommendation to 47 feet freshwater effectively immediately after it was reduced to 46 feet freshwater on May 5, 2021. The notice was shared earlier today by the Crescent River Port Pilots’ as implanted by their Safe Navigation Committee of Louisiana for the state-commissioned river port pilots:
“Based on the current conditions, the maximum recommended freshwater draft is 47’ effective immediately. Thanks.”
MISSISSIPPI RIVER SHIP CHANNEL DEEPENING PHASE 1:
The Phase 1 areas of the Ship Channel have all been deepened to 50 feet through the use of the four dredges listed below. The USACE utilized three contracts to deepen the Ship Channel from Venice to the Gulf of Mexico (Phase 1). The USACE expects to complete the deepening project in four progressive upriver phases to the upper end of the MRSC at Mile 233.8 AHP (Baton Rouge). The details on the dredge contracts worked under Phase 1 of the historic river deepening project are detailed below:
Southwest Pass Cutterhead Dredge Rental Contract #1-2020: was awarded to Weeks Marine on August 20, 2020. The cutterhead dredge CAPTAIN FRANK dredged under this contract from
September 11, 2020 to March 3, 2021 and the E.W. ELLEFSEN dredged on this deepening contract from November 18, 2020 and completed the last assignment on March 19, 2021.
Southwest Pass Cutterhead Dredge Rental Contract #2-2020: was awarded to Manson Construction on August 27, 2020. The cutterhead dredge ROBERT M. WHITE worked on this contract from October 23, 2020 until completion on March 18, 2021.
Southwest Pass Hopper Dredge Rental Contract #9-2020: was awarded to Manson Construction on September 21, 2020. The GLENN EDWARDS worked under this deepening contract from
January 14, 2021 to May 7, 2021.
INDUSTRY HOPPER DREDGES WORKING IN THE AREA OF SOUTHWEST PASS (SWP):
STUYVEASNT: The industry hopper dredge STUYVESANT (Dutra Group) continues working on assignment from Mile 13.0 AHP to Mile 12.0 AHP. The STUYVEASNT is working under Southwest Pass Hopper Dredge Rental Contract #6-2020 that was awarded to the Dutra Group in Fiscal Year 2020 to perform channel maintenance in Fiscal Year 2021. The STUYVESANT began work under this contract on March 24, 2021.
NEWPORT: The industry hopper dredge NEWPORT (Manson Construction) is dredging on assignment at Cubits Gap (Mile 3.5 AHP to Mile 2.5 AHP). The NEWPORT is working under Southwest Pass Hopper Dredge Rental Contract #7-2020 that was awarded to the Manson Construction in Fiscal Year 2020 to perform channel maintenance in Fiscal Year 2021. The NEWPORT began work under this contract on April 3, 2021.
GLENN EDWARDS: The GLENN EDWARDS (Manson Construction) is working on channel maintenance at the Head of Passes (Mile 1.0 AHP to Mile 1.0 BHP). The hopper dredge is now working under Southwest Pass Hopper Dredge Rental Contract #3-2020 that was awarded in Fiscal Year 2020 to perform channel maintenance in Fiscal Year 2021. The GLENN EDWARDS began work under this contract on May 7, 2021.
GOVERNMENT HOPPER DREDGES WORKING IN SOUTHWEST PASS (SWP):
WHEELER: The USACE’s hopper dredge WHEELER continues working on assignment in SWP from Mile 11.6 BHP to Mile 15.1 BHP. The WHEELER began work under Readiness Exercise #1-2021 on April 25, 2021 and is expected to complete this Readiness Exercise on May 17, 2021.
CUTTERHEAD DREDGE(S) IN THE HOPPER DREDGE DISPOSAL AREA (HDDA):
ILLINOIS: The cutterhead dredge ILLINOIS (Great Lakes Dredge and Dock) has removed and beneficially used approximately 5.5 million cubic yards (mcy) of material from the HDDA under Hopper Dredge Disposal Area Cutterhead Rental Contract #1-2019. The contract includes the removal of 10 mcy in the base with options to add an additional 4 mcy. The project is expected to be completed by early 2022. The material is beneficially being used in the West Bay Receiving Area through a submerged dredge pipeline that will have to be removed up completion of the project. The pipeline retrieval will require at least one complete closure on the Ship Channel in the immediate vicinity of the submerged pipeline (Mile 2.0 AHP to Mile 0 – the Head of Passes).
The Carrollton Gauge (New Orleans) reading at 1900 hours today was 11.58 feet with a 24-hour change of + 0.23 feet. The latest crest recorded on the Carrollton Gauge was 15.44 feet at 1700 hours on April 16, 2021. The National Oceanic and Atmospheric Administration’s (NOAA) National Weather Service Extended Streamflow Prediction (28-Day) for the Carrollton Gauge issued today forecasts stages to continue a slow rise to 12.3 feet on May 20 and then to begin a slow fall to 9.7 feet on June 8 (2021).
The Baton Rouge Gauge reading at 1400 hours today was 31.26 feet with a 24-hour change of + 0.24 feet. The National Oceanic and Atmospheric Administration’s (NOAA) National Weather Service Extended Streamflow Prediction (28-Day) for the Baton Rouge Gauge issued today predicts stages to continue a slow rise to 33.50 feet on May 19 and then to begin a slow fall to 26.3 feet on June 8 (2021).
The graph below is reproduced from NOAA’s National Weather Service website and represents an experimental product to account for the complexity of accurately predicting long-range precipitation. This forecast projects stage levels based on expected precipitation for 2 days (top) and 16 days (bottom) and was developed within the North American Ensemble Forecast System (NAEFS) computer model and highlights Quantitative Precipitation Forecasts (QPF). Along with the forecasts, a shaded area is also provided to indicate uncertainty for the forecast each day in the future. These plots are experimental and not an official forecast product.
Please note the alignment between the 2 and 16 day forecasts.
The following explanation was recently offered by a member of the Lower Mississippi River Forecast Center to further explain the diagram above.
The accuracy of the forecasts are built into the shaded areas in the graphic, the shading represents historical data and errors determined by previous stage forecasts. Two-thirds of the time the future stage will be within the shading area and one-third of the time it will be outside of the shaded area. (Similar to hurricane landfall predictions).
A good reminder is that the forecast for New Orleans (Carrollton Gauge) is more accurate than areas further upriver especially as far upriver as Cairo (Illinois).
“The accuracy of the forecast can also be seen in the upper/lower bounds of the shaded area. The difference in the upper/lower bound of the shading at Cairo is roughly 10 to 15 ft by day 28. For New Orleans, it is roughly 3 to 4 feet.
Bottom-line, the New Orleans forecast is pretty good 2 to 3 weeks out since rainfall doesn't influence the forecast for a couple of weeks but as you go further upstream, the rainfall will cause stages to react quicker so forecasts are generally good 1 to 2 weeks out by the time you get to Cairo. The 16 day forecast typically performs better than the 2 day forecast.
If the rain is already on the ground and no more rain is forecast for the next couple of weeks, you can add an additional 1 to 2 weeks on the statement above.”
Please utilize the attached reports for complete details including the year to date plot of the Carrollton Gauge levels.
Best Regards,
Sean M. Duffy, Sr.
Executive Director
Big River Coalition
http://bigrivercoalition.org
Phone (504) 833-4190 x 805
Cell (504) 338-3165
