Alternative D1 ("One Lake")

Alternative D1 ("One Lake") includes:

• Excavation of 954 acres along 9 miles of the Pearl River
• Construction of a new dam downstream of I-20 creating a permanent impoundment*
• Non-structural elements of A1 (elevations and floodproofing)
• Canton Club,  McLeod, Cany Creek, and Richland Levees
• Recreation features

*Notes

• The proposed dam "does not provide any flood control benefits, and construction of the weir necessitates additional pumping needs at existing levees as well as seepage protection in the form of berms and slurry walls on existing levee segments" 2025 USACE RDEIS, App I, p 36
• A fish ladder would be included in the dam design to facilitate fish passage over the dam; however, there will not be sufficient water available to support fish passage throughout the entire calendar year. (2025 USACE RDEIS, Appendix I, p 35)

COSTS	Alternative D1 ("One Lake")
Project First Cost*	$873-$917 million*
Average Annual Cost (Investment + Maintenance)	$36.2-$38 million
Total Benefits (Damages Reduced + Recreation Benefits)	$25.2 million
Net Benefits	(-$11 million--$12.8 million)
Benefit Cost Ratio	0.7
Local Cost Share	$305-$320 million, plus $700k annual costs

*The USACE Section 902 Maximum Project Cost Limit recalculated for FY2025 is $475,688,000

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Features

Excavation

2025 USACE RDEIS

954 acres would be excavated along the Pearl River from River Mile 285 to River Mile 294 to improve water conveyance. The width of excavation would range from 500-2,600 feet and depth from 0-13 feet. The USACE predicts that excavation would provide reduction of flood elevations within the excavation area and for over 8 miles upstream. 

Excavated fill would be placed in designated disposal areas on the protected and unprotected side of existing levees as well as other locations within the flood plain. The disposal fill areas would cover 523 acres with 9.38 MCY (million cubic yards) of excavated fill. The excavated fill material would be used to create land areas ranging from 3-93 acres. The newly created areas could allow for expanded riverfront access, natural areas, along with recreational opportunities. Up to 1.6 MCY of fill (100 acres of fill 10 feet high) would be provided to the Rankin-Hinds Pearl River Flood and Drainage Control District for additional usage within the project area. (2025 USACE RDEIS, Appendix E, p 48-49)

Dam

2025 USACE DEIS

Alt D1 includes construction of a new dam at River Mile 286.5 to create a "Lake Surface Area" of 1,556 acres.  The dam would be built to an elevation of 256 ft, six feet higher than the current weir at J.H. Fewell Drinking Water Plant.  Portions of the dam would be submerged during normal flow allowing excess water to pass downstream and a low flow structure is included in the design. Water would pass over the weir or through the low flow structure with inflow into the lake approximately equaling outflow at any given time. The new dam would not provide any flood control benefits but would create a permanent lake impoundment. ​

Click for more info about the dam and excavation

Levees

LEVEE	Location	Length	Structures Protected	Area Protected	Benefit/Cost
Canton Club	NE Jackson	1.4 miles	over 250 homes	100 acres	4.2
McLeod	NE Jackson	2.3 miles	415 homes	170 acres	0.9
Cany Creek	S Jackson	1 mile	40 homes	137 acres	0.3
Richland	East Bank of Pearl	1.15	40 structures	122 acres	0.1
TOTAL	-	5.85 miles	745+ homes	529 acres	-

Note: 2 homes at the riverbank will need to be acquired for McLeod Levee construction. Other levees may require public and private infrastructure relocation. source: 2025 USACE RDEIS, pages 131-133

Canton Club Levee

McLeod Levee

Cany Creek Levee

​Non-Structural Component

Alternative D1 would include the non-structural components of Alternative A1 including some voluntary home elevations and floodproofing. 

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The following options were removed from the list of potential features:

• Clean out and sustained maintenance of tributaries: The USACE reports that this feature was removed upon identifying that this work is being undertaken by the NRCS, State and other local entities through the Mississippi Watershed projects.
• Levee setbacks: This feature was determined by USACE to provide limited flood risk reduction benefits.
• Demolition of the existing weir at J.H.Fewell Drinking Water Plant: USACE notes that demolition of the existing weir is not needed as the existing weir is submerged and does not impede water flow and that the existing weir would be necessary to maintain adequate water supply should a new weir not be constructed.

source: 2024 DEIS, Main Report, PDF page 115

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Adverse Impacts

Water Quality and Drinking Water Supply: Adding a large weir could increase sediment loads enough to alter the river water chemistry and induce failure at the existing J.H. Fewell Drinking Water Plant. (source: 2024 DEIS, PDF page 201) The new weir and channel improvements could disturb the known Hazardous Toxic Waste Sites (HTRW) enough to cause probable exposure to  toxic contaminants within the ponded area at the inflow to J.H. Fewell Drinking Water Plant. (source: 2024 DEIS, PDF page 201). "Additional study could be needed to determine the best methods of design and construction to limit the impact to potable water throughout the system in respect to contaminant retention due to pooling and sediment loading prior to treatment." 2024 DEIS, PDF page 202

Mitigation: A USACE 2023 internal presentation states: “Identification of lands ongoing for terrestrial mitigation, extremely challenging (if not impossible) to mitigate riverine impacts of this proportion. Experts agree that restoring large systems such as this or even compensating for such great function and habitat loss to a truly desirable condition (as existed pre-disturbance) is impossible to achieve. Impoundment removal seems to be the national trend, due to significant adverse impacts of impoundments on river systems for natural resources and humans.” The USFWS estimated in its Fish and Wildlife Coordination Act Report: "Preliminary analysis shows total mitigation costs (based on bank credit purchase) for forest types and palustrine habitat could exceed $1 billion, which excludes riverine mitigation costs. We expect riverine mitigation to be costly since both function and habitat loss need to be compensated. Therefore, costs would greatly exceed $1 billion." (source: 2024 USACE DEIS, Appendix J, PDF page 44) 

Induced Flooding: Floodwaters will move more quickly through the excavated project area, adding additional floodwater to the area south of the new dam. Induced flooding caused by Alternative D1 includes:

• 11 structures receiving additional flooding in the ground floor during 100-year flood
• 97 structures receiving additional flooding in the ground floor during 200-year and 500-year floods
• 81 acres receiving additional flooding in the ground floor during 100-year flood
• 5,822 acres receiving additional flooding during 200-year and 500-year floods

Relocations or Removal Actions Required:

• Relocating 4-5 utility transmission lines
• Bridge countermeasures
• Mitigating potential HTRW (Hazardous, Toxic, Radiological Waste Sites) and other hazardous waste sites within the floodplain. USACE is prohibited from undertaking HTRW work on behalf of the Rankin Hinds Pearl River Flood and Drainage Control District (the Non Federal Sponsor). "Consideration may be given to designating an HTRW avoidance alternative as the National Economic Development plan when costs and risks of response actions are uncertain." 2024 DEIS, PDF pages 94-95.         

High Cost of Alt D1:

• Projected First Cost for Alt D1: $873-$917 million
• Total Project Cost (accounting for inflation and interest): over $1 billion (2025 USACE RDEIS, Appendix R)
• Maximum Project Cost Limit: $475 million (*An increase in the authorized project cost would require approval from Congress)
• Current Federal Cost Share Appropriation: $221 million (appropriated in Oct 2022)

TOTAL PROJECT COST	D1 (High Cost)	D1 (Low Cost)	Local Cost Share
Relocations	$7 million	$7 million	35%
Dams	$58 million	$58 million	100%
Fish and Wildlife Facilities	$159 million	$112 million	35%
Channels and Canals	$351 million	$351 million	35%
Levees and Floodwalls	$125 million	$125 million	35%
Pumping Plant	$54 million	$54 million	100%
Recreation Facilities	$6 millon	$6 million	50%
Bank Stabilization	$99 million	$99 million	35%
Lands and Damages	$109 million	$109 million	35%
Planning, Engineering, & Design	$62 million	$59 million	35%
Construction Management	$53 million	$50 million	35%
TOTAL*	$1 billion ($1,088, 438,000)*	$1 billion ($1,035,003,000)*	-

source: 2025 USACE RDEIS, Appendix R, pages 18-19)

Costs to Rankin Hinds Pearl River Flood and Drainage Control District, the Non Federal Sponsor (NFS):

• The local Drainage District, Rankin-Hinds Pearl River Flood and Drainage Control District, shall contribute 35 percent of total project costs. (Source: 2024 Commander's Report, pages 13 and 14)  The Drainage District has not indicated how they will pay for their portion of the project costs. 
• The local Drainage District is solely responsible for 100% of the costs for remediation of the Hazardous, Toxic, Radiological Waste (HTRW) Sites in the project area, including the costs of any studies and investigations.
• The local Drainage District shall acquire the real property interests that the Government has determined are required for the construction, operation, and maintenance of the Project. 
• The local Drainage District shall perform or ensure the performance of the relocations necessary for construction, operation, and maintenance of the Project 
• In addition, the local Drainage District will be responsible for Estimated Annual Operation and Maintenance Costs of $700,000/year. Local Drainage District revenues are obtained through a 4.75-mil tax assessment on properties protected by the levee system. The majority of the tax revenue comes from properties located in Rankin County. The state-owned properties on the Jackson side of the Pearl River do not pay taxes.

Harm to endangered and threatened species: The USACE notes that, despite having a smaller footprint that the original "One Lake" project design, this alternative "will still cause major long-term negative impacts to fisheries and aquatic resources.” Threatened, endangered, and protected species that will by negatively impacted by Alternative D1 include the Gulf sturgeon, Pearl River map turtle, ringed sawback turtle, alligator snapping turtle, LA pigtoe mussel, tricolored bat, monarch butterfly, and bald eagle.

2024 USACE DEIS, PDF page 216, LeFleurs Bluff State Park

Loss of Public Lands: 78 acres, 16% of LeFleur’s Bluff State Park, Jackson’s only public access to the Pearl River and a popular recreation area, would be excavated and permanently under water, according to the map published in the 2024 USACE DEIS. 

LeFleurs Bluff State Park has been the recipient of $1,422,999 in  Land Water Conservation Act grant funding. (not adjusted for inflation)  A condition of the grant is that: "No property acquired or developed with assistance under this section shall, without the approval of the Secretary, be converted to other than public outdoor recreation uses."

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Additional studies required:  Alternative DI will require a lengthy process of additional NEPA (National Environmental Policy Act) studies and analysis. Many critical studies and analyses are missing or incomplete in the 2025 USACE DEIS. The USACE states in the document that many of the studies required NEPA process will not be conducted until the Pre-Construction, Engineering, and Design (PED) Phase, which occurs after the USACE Assistant Secretary of Civil Works makes his Record of Decision about the project. A few of the further required studies are listed below. 

• Mitigation plan (to be developed during PED and included in a subsequent NEPA document)
• 404(b)(1) Clean Water Act Analysis (to be conducted during PED)
• Bridge countermeasures to prevent failure of main channel bridges (major evaluation will be a PED effort)
• Sedimentation study (to be conducted during PED) "During design, additional study and verification would be needed to confirm that adding a large weir would not induce sediment loads to alter the incoming chemistry in such a way to induce failure at the existing J.H. Fewell Plant or any other proposed structure along the newly ponded area. A sedimentation study has been proposed to be completed during the PED phase of this study." (PDF page 201)
•  Velocity Analyses (to be conducted during PED)
• Utility Relocation Plan (to be conducted during PED) "It is estimated that 5 to 6 of these lines will require additional utility relocation costs. Coordination with the operating entity to determine specific requirements of each transmission line will be conducted during PED."  (PDF page 124)
• LeFleurs Bluff State Park Mayes Lake work (to be determined during PED) "Mayes Lake (Sta. 310+00±) may need tie-in work to maintain its current level. A determination about the tie-in work would be made during the PED phase." (PDF page 130)
• Railway Bridge Planning (to be conducted during PED) "There are a total of 2 active railroad bridges within the project area. All efforts would be made to avoid, monitor, and protect these structures. Additional modeling is required to validate these assumptions during PED. If avoidance is not possible, then coordination with the operating entity to determine specific requirements of each railway bridge will be conducted during PED."(PDF page 131)
• Fish Passage Design (coordinated during PED) "The fish passage design will be coordinated with The Service and state agencies during the PED phase." (PDF page 135)
• Borrow Area Analysis (investigated during PED) "Borrow opportunities would be further investigated during PED and a supplemental NEPA document would be prepared at that time." (PDF page 137)
• Hazardous Toxic Waste Site mitigation (to be determined during PED)
• Historical and Cultural Site Assessments (adjusted during PED) "The Jackson MSA has significant historical and cultural site presence, final site locations would be adjusted during PED following completion of cultural resource surveys." (PDF page 147)
• Habitat Mitigation (completed during PED) "Habitat Mitigation would be achieved by implementing Corps constructed mitigation projects and/or purchasing of mitigation bank credits. Further planning and analysis would be completed during PED to determine which strategies, stand alone or combined, would fully compensate for habitat impacts." (PDF page 155)
• CTO Implementation (additional analysis could be required during PED) "To implement multiple flood risk management features and a more comprehensive solution, additional authority is required either an increase in the total authorized project cost under Section 3104 or a programmatic authority to implement flood risk management features in the Pearl River Basin similar to CAP Section 205 projects. Additional analysis and design, feasibility level decision documents, and supplemental NEPA documentation would be required during the PED phase if such solutions are recommended." (PDF page 256)
• Levee Studies (calculated in PED) "The currently proposed Alt C being evaluated by USACE does not include any alignment or height changes to the existing Jackson Fairgrounds Levee." "It is also unknown whether the proposed alternative will change the overtopping location on the levee system. This overtopping frequency and location would need to be calculated in PED phases." (PDF page 263)
•  Impacts of CTO on tributary flooding (the DEIS states that Alt C would increase flooding along the tributaries but does not discuss CTO impacts on tributaries). “It is recommended that a survey of tributaries and structures along the tributaries be incorporated into the model to better estimate flooding and impacts along tributaries.” (PDF page 247)
• Water quality impacts – additional modeling/data required to determine if either CTO is “viable”
• Storm Water Pollution Protection Plan (SWPPP) (during PED, downstream impacts will be assessed and coordination with the resource agencies will take place) 
• Water supply impacts, "Depending on the method and means of selected features additional study could be needed to determine the best methods of design and construction to limit the impact to potable water throughout the system in respect to contaminant retention due to pooling and sediment loading prior to treatment." (PDF page 202)
• Weir design

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Pearl Riverkeeper asks that everyone make his or her own decision regarding the Pearl River Flood Risk Management Project using sound science and engineering.  We encourage the review and thorough analysis of all available information.  We welcome comments and feedback.  Please email Pearl Riverkeeper or visit our Facebook  for comment space.  Our publishing, or re-publishing, of anyone else's research or opinions is not an endorsement on our part of those conclusions.