Chapter 1: Conservation, Tailwater Recovery, and On-Farm Storage ______
Table of Contents Section 1: Introduction ______3 Plan Summary ______3 Section 2: Formulation and Comparison of Alternatives______7 No Action______7 Actions ______7 Action 1 ______7 Action 2 ______8 Action 3 ______16 Water Conservation ______18 On-Farm Water Development ______18 Sunflower River Sediment Control ______20 Section 3: Environmental Impacts ______21 References Cited ______23 Appendix A: Cost of Conservation Practices______24 Appendix B: Assumptions used for Economic Evaluation ______25
List of Tables Table 1: Costs for tailwater ponds and on-farm water storage reservoirs. ______19 Table 2: Sample tailwater recovery pond costs and benefits.______19 Table 3: Sample storage water reservoir costs and benefits. ______19 Table 4: Monthly suspended sediment load calculated for the Sunflower River watershed at the town of Sunflower. Sampling site 20 in Figure 4. ______20
List of Figures Figure 1: Permitted wells in Mississippi. ______5 Figure 2: Land irrigated from groundwater wells and surface water relift. Catfish ponds are filled from groundwater wells. ______6 Figure 3: Mississippi Delta’s 11 digit watersheds.______10 Figure 4: Mississippi Delta’s major river watersheds. ______11 Figure 5: Farm Service agency tract boundaries for Sunflower County. ______12 Figure 6: NRCS water quality sampling sites in the Mississippi Delta.______13 Figure 7: Bolivar County conservation database example. ______14 Figure 8: Satellite imagery example. ______15
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Section 1: Introduction
Plan Summary Actions involve planning the installation and use of currently available soil and water conservation measures on a coordinated watershed basis to improve water use efficiency to stop the 100,000 acre-feet per year overdraft by improving water use efficiency, maximizing the use of rainfall, and additionally to have a positive impact on receiving water quality. The key to successfully implementing the installation of conservation practices such as tailwater recovery ponds and storage reservoirs is to locate them in the watershed where they can be most effective. This requires watershed planning and landowner cooperation. Principal project measures were developed to make this type of planning and installation possible.
Project measures include the following;
1. Develop a network to obtain and coordinate individual farmer and agency support. 1. Lay the framework to develop a GIS capable of supplying regional resource data in natural watershed units. 2. Lay the framework to develop a method to plan and implement individual practices on a coordinated watershed basis. 3. Begin to develop the implementation plan to install tailwater recovery ponds to serve wells used to irrigate cotton, corn, soybeans, and rice acres. 4. Begin to develop the implementation plan to install on-farm water storage reservoirs. 5. Begin to develop the implementation plan to install appropriate water conservation and water quality practices. Proposed practices for water storage, conservation, and quality protection are those recommended by the USDA NRCS Field Office Technical Guide for Mississippi. Descriptions of these practices are presented in Section 3 Formulation and Comparison of Alternatives. The 6/3 method for water savings in catfish ponds was recommended.1
It was important to focus natural resource management efforts toward scientifically documented issues and solutions so that the limited financial and human resources available to implement solutions could be spent in a manner that would produce the most effective combination of environmental and economic results. It was also important to remember that nature ignores manmade political boundaries. A watershed approach to planning across competing interests, programs, and political boundaries was essential to the success of any regional water resource management program. In fact, coordinating local, state, and federal programs on a watershed basis to get more from every dollar invested is a common sense approach to implementing all conservation and environmental programs.
Land treatment for water conservation can be used to increase irrigation and water use efficiency decreasing the overdraft by decreasing pumping. Practices included measures for irrigation water management, irrigation water conveyance, and tailwater recovery. A list of these practices and the cost of implementation are supplied in Appendix A of this chapter.
There were about 322,000 acres of furrow-irrigated cotton and corn, and 415,000 acres in rice soybean rotation using some 6,700 wells (Figures 1 & 2). 2 Past experience indicated that one tailwater recovery system could handle the water from about 4 wells. A total of 1,675 ponds would need to be constructed to serve all of these row crop wells.
Center pivots irrigate another 210,000 acres from about 1,140 wells. (Figure 2) Studies done by Mississippi NRCS in the late 1980s indicated that these systems were running at close to maximum efficiency; therefore, no conservation practices were needed to improve these systems. A cost comparison of an efficient, readily operator accepted, pivot system to construction of a less accepted, land and labor
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intensive tailwater recovery system, indicates that it may be more feasible to cost share on conversion to pivot systems rather that installation of tailwater systems. 3
There are about 115,000 acres of catfish ponds operating on about 1500 wells currently permitted in the Delta. (Figure 2) Storage and use of rainwater could potentially cut water needs in a pond from 22 inches to 11 inches per season. This would be potential water savings of 105,000 acre feet. This practice is now commonly called the 6/3 method. 1 Implementation of this practice through education efforts should make additional efforts in pond water management unnecessary.
Industries can become more water efficient by eliminating one pass cooling and by recycling water used in manufacturing processes.
Municipalities can improve water conservation through public education programs, monitoring and maintenance of distribution systems, and through the use of gray water for applications where potable water is not necessary such as watering public parks and golf courses.
Increasing the use of rainwater by building on-farm storage reservoirs was also an option.
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Figure 1: Permitted wells in Mississippi. Each dot represents a well with a 6 inch or greater casing.
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Figure 2: Land irrigated from groundwater wells and surface water relifts. Catfish ponds are filled from groundwater wells.
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Section 2: Formulation and Comparison of Alternatives
No Action A no action alternative provides no conservation practices, structural or management, for improved use of existing water sources, no development of new water supplies, and no environmental protection for wildlife, fisheries, or water quality.
Major uses of water in the Delta, irrigation, industry, municipal, wildlife and fisheries would continue with the no action alternative. However, the potential to permanently harm the Aquifer by water mining, which can collapse sand and gravel layers, exists with the no action option. Groundwater costs would increase greatly as the Aquifer lost productivity and wells had to be placed at increasingly deeper levels within the aquifer. Constraints on industrial, municipal, and agricultural development would occur as readily available water supplies dwindled. Loss of wildlife and fisheries habitat would continue to occur as baseflows in rivers decreased. Ultimately, destruction of the Aquifer could eliminate irrigated agriculture and catfish production in the Delta. Actions The actions needed and major tools to be developed to help solve the problems documented in this portion of the study were 1. Develop a network to obtain and coordinate individual farmer and agency support. 2. Lay the framework to develop a GIS capable of supplying regional resource data in natural watershed units. 3. Lay the framework to develop a method to plan and implement individual practices on a coordinated watershed basis. 4. Begin to develop the implementation plan to install tailwater recovery ponds to serve wells used to irrigate cotton, corn, soybeans, and rice acres. 5. Begin to develop the implementation plan to install on-farm water storage reservoirs. 6. Begin to develop the implementation plan to install appropriate water conservation and water quality practices.
Details of these actions were discussed in the following paragraphs. Action 1 A network to obtain individual farmer and agency support to implement solutions to locally identified natural resource concerns would be established. Individual watershed solutions would be developed to be consistent with local, regional, and state resource objectives. This network would be essential to the success of planning across program and political boundaries for installing or implementing management practices in the coordinated watershed approach proposed in this project.
Landowner support and participation would be organized through county and area NRCS, YMD, and SWCD and Delta Council. Mississippi NRCS has offices with local Soil and Water Conservation Districts to cover all of the counties in the Mississippi Delta. NRCS provides technical assistance where planning is needed to implement a natural resource solution.
YMD is a regional governing authority with water resource planning and regulatory responsibilities. Its boundaries include all or part of 17 Delta counties covering about 7000 square miles (4,480,000 acres) in northwestern Mississippi. YMD is run by a 23 member board of directors. The board is appointed by county supervisors and includes a wide range of interested parties such as farmers, city engineers, university faculty, and small business operators. The water management district has a full time staff of 11 professionals. The district is located on one of the largest experiment stations in the United States, the Delta Branch Research and Extension Center in Stoneville, MS. They are uniquely situated to cross county boundaries and plan on a regional level.
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County SWCD local workgroups represent the smallest public planning unit involved. These local workgroups have been established in each county to establish priority concerns to be addressed through the Environmental Quality Incentive Plan. Workgroups were made up of farmers within a county, the SWCD chairperson, the USDA Farm Service Agency (FSA) representative, the NRCS district conservationist and a YMD commissioner or staff. SWCD commissioners are local community leaders.
The Delta Council is an area economic development organization representing eighteen Delta and part Delta counties of Mississippi. It was organized in 1935 to provide a medium through which the agricultural, business, and other professional leadership of the area could work together to solve common problems and promote the development of the economy of the area. It is supported and financed by dues- paying members and by the counties it represents. Delta Council is an excellent example of citizens in action. It organized about 370 meetings in 1997 alone, drawing from the input of more than 2000 people involved in problem solving projects.
Together, these groups make up a strong nucleus of local leadership to lead local involvement.
Other planning partners could include the following.
• Local farmers and other land users • Levee Boards • Drainage Districts • Duck's Unlimited • Farm Bureau • Delta Wildlife Foundation • Mississippi Department of Wildlife Fisheries and Parks • Mississippi Department of Environmental Quality • Mississippi Department of Forestry • Mississippi Soil and Water Conservation Commission • U.S. Forest Service • U.S. Fish and Wildlife Service • U.S. Army Corps of Engineers
Action 2 Develop a GIS capable of supplying regional resource data in natural watershed units. Relational databases used within a GIS are the tools needed to replace political boundaries with watershed boundaries. These tools provide an excellent way to not just organize data but to visualize and plan how projects will work together to solve problems. For example, the Mississippi Delta's 17 counties are composed of approximately 90 watersheds. (See Figure 3) Very few of these watersheds reside in only one county. When watersheds were grouped into major drainage systems, the limitations resulting from the use of county boundaries were even more obvious (Figure 4)
Relational databases within a GIS have been developed for the Delta by and are housed at YMD. YMD staff will maintain GIS hardware, software, and data. An effort to combine this GIS with FOCS tables is being planned. This would allow planners access to any NRCS installed practice for watershed inventory and planning. Currently available layers will be used as the foundation to begin an inventory of watershed land and water resources. Currently available layers include the following.
1. area boundaries, counties, and roads 2. streams and lakes 3. permitted water use by agriculture (irrigated acres by groundwater and surface water, fish culture, center pivots, etc.) (See Figure 2)
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4. FSA tract boundaries for 5 counties, other counties are in progress (See Figure 5) 5. Water quality data from the 22 NRCS water quality sampling sites (See Figure 6)
Other layers would have to be developed to complete the inventory to facilitate effective watershed planning. These include the following.
1. An inventory of conservation practices already in place in the watershed based on site visits by staff on the project (Figure 7) NRCS FOCS would also be an excellent source for this data. 2. land use, crop type, maps from satellite imagery (Figure 8)
These maps could be used to develop additional layers for a variety of purposes in watershed planning for natural resource management. The following is a partial list.
1. determining cropping land use, particularly nonirrigated land to be integrated with water use permit database of irrigated acres 2. forest and wetland delineation 3. delineation of other wildlife areas (private hunt clubs, refuges, etc.) 4. delineation of land actually flooded for winter waterfowl habitat 5. determining actual flooded acreage after a flood event
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Figure 3: Mississippi Delta’s 11 digit watersheds.
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Coldwater Tallahatchie
Sunflower
Quiver
Bogue Phalia
Yazoo
Steele Bayou
Figure 4: Mississippi Delta’s major river watersheds.
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T4938
Figure 5: Farm Service agency tract boundaries for Sunflower County.
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Figure 6: NRCS water quality-sampling sites in the Mississippi Delta.
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Figure 7: Bolivar County conservation database example.
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Figure 8: Satellite imagery example. Humphreys County.
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Action 3 Implementation of practices on a coordinated watershed basis would provide increased flexibility to enhance both program delivery and effectiveness. Local partners along with local and federal agencies would establish watershed goals and plans to address resource concerns. Agricultural land and water management practices and water supply augmentation can not be effectively implemented in isolated politically defined areas. One county can put practices in place in a watershed only to have them rendered ineffective by activities from a neighboring county on the same watershed. The proposed implementation approach would allow for coordinated (with WRP, WQIP, FIP, etc.) implementation of agricultural land and water management practices and water supply augmentation on a watershed level.
EPA has renewed their efforts to use the watershed approach to planning as the most effective way to protect aquatic ecosystems. EPA has determined that this approach provides a framework and focus for effective integration of existing programs and is shifting their support from reporting from a state basis to reporting on a watershed basis. One result that EPA believes would be beneficial to all involved would be the implementation of planning processes in a coordinated manner on a watershed basis. Emphasis is placed on the importance of stakeholders working together. 4 The entire concept of coordinated resource planning at the watershed level as well as EPA's goals to align ongoing programs, such as Total Maximum Daily Loads (TMDL), and to develop tools to make the approach work, fit very well into the goals of this study. The results of implementation of these study practices would demonstrate to natural resource planners how to reach these EPA goals in coordination with other natural resource goals.
Planners would use the GIS data to:
1. Complete the water and related land resource inventories for the watershed. 2. Identify major water quality and quantity issues in the watershed. Set goals for the watershed based on identified needs and opportunities. 3. Develop a plan to most effectively use financial and natural resources in the watershed to meet the planned watershed and regional watershed goals for the identified concerns such as water supply, water quality, wildlife habitat and sustainable agriculture. This plan should be directed by the local workgroups participating in the original setting of goals. 4. Determine best management practices and locations for implementation or installation of practices, the NRCS Field Office Technical Guide (FOTG) management practice lists would be used to choose applicable practices that provide the most benefit per dollar spent in meeting the stated goals. Installation of practices to meet these goals will be through the implementation of USDA programs such as EQIP, Wetland Reserve Program, and Conservation Reserve Program.
Potential practices were taken from the NRCS FOTG. Those listed below were considered to be good candidates for implementation. Residue management was a requirement of EQIP, the rest were listed roughly by what they cost to implement relative to each other. Practices 9 and 10 were not listed by cost. They were included as practices that specifically prevent accidental contamination from agricultural activities. Farmer acceptance of any of these practices could be increased with planned outreach activities concerning the effectiveness and benefits of the practices as well as by offering incentives.
1. Seasonal residue management (FOTG Practice 344) can be a very effective tool to prevent winter and early spring runoff induced erosion and sediment loss. This is not a popular option because many Delta farmers feel that fall tillage is essential to getting an early planting date the following spring. 2. Structures for water control (FOTG Practice 587) were one of the least expensive options for pooling water to slow runoff flow and allow soil particles to settle decreasing sediment loss and protecting water quality. A management plan would be developed for each structure so that boards could be installed in winter months to provide winter waterfowl habitat and
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reduce winter sediment runoff. This option has widespread farmer acceptance increasing the chances of installing this practice in large enough numbers to achieve project goals. 3. Buffer Zones: forested buffer strips, vegetated filter strips, waterways, and turnrows (FOTG Practices 391, 393, 412, ) are not widely used, but do provide a low cost alternative that, with a good selection of plant types, could become viable options. Forested buffer strips are uncommon in agricultural landscapes but provide an opportunity for greatly reducing sediment transport into surface water and enhancing water quality. Buffer strips have been shown to reduce sediment and soluble nutrients as much as 90%5 and effects are seen even in the first year of tree growth.6 4. Landforming and establishing permanent pads and levees (FOTG Practice 462) are practices with widespread farmer acceptance. This is an option implemented most often on rice/soybean ground. There are about 240,000 acres of rice acreage in the Mississippi Delta. 5. Tailwater recovery ponds (FOTG Practice 447) planned to store water year round, could help provide solutions to many of the problems of water supply and water quality because they fulfill several functions. Direct inputs to water quality from sediment and nutrient enriched runoff are prevented because runoff is captured before it reaches a primary drain and leaves the farm. Tailwater recovery ponds can serve as mini wetlands. They serve many of the same functions. For instance, they store water reducing flooding potential of downstream lands, they slow water allowing sediment and associated nutrients to settle, they provide some residence time for nutrient recycling, they provide wildlife habitat, and they reduce groundwater pumping. If tailwater recovery ponds were used in enough places, overall water quality in Delta surface waters would improve. Water conservation would reduce pressure on the alluvial aquifer helping to solve low flow water volume, associated water quality problems, and the Aquifer overdraft water supply problems. 6. Cost-sharing for conversion of surface irrigation systems to overhead sprinkler irrigation systems (FOTG Practice 449). YMD irrigation well permit database records indicated that center pivot systems currently irrigate approximately 208,400 acres from 1140 wells. Studies done by the NRCS in the late 1980s indicated that these systems were operating near maximum efficiency, average 73%,. No conservation measures would be required to improve the system efficiency. Therefore, conversion of less efficient systems could both decrease runoff improving water quality and increase the efficiency of water use conserving water helping to alleviate supply problems. 7. Tree Planting (FOTG Practice 612) on economically marginal cropland would decrease sediment movement by increasing surface roughness and lengthening detention times of surface runoff. Additionally, other wetland functions and values would be restored, increasing regional biodiversity and enhancing wildlife habitat. Use of more intensive restoration practices than allowed under current WRP implementation (e.g., interplanting and use of fast-growing native species as a nurse crop) would recapture functions more quickly than with current practices. 7 8. Irrigation storage reservoirs (FOTG Practice 436) could be constructed to provide new water supplies to support adjoining irrigated cropland. Runoff from rainfall and irrigation in a drainage ditch would be pumped into an on-farm storage reservoir for use as irrigation water supply. 9. Agrichemical mixing centers (FOTG Practice 201) properly planned and placed would reduce the incidence of accidental contamination of water sources from spills of chemicals. 10. Decommissioning of abandoned wells (FOTG Practice 351) to prevent contamination of groundwater source, the Mississippi River Valley Alluvial Aquifer.
Costs to implement these practices were documented in Appendix A of this chapter.
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Water Conservation Another consideration is the cost of water conservation. Water conservation can be achieved optimally by keeping all water on the farm where it originates and catching precipitation. Tailwater recovery ponds were used as an example of how to achieve the goal of stopping the currently identified 100,000 acre foot per year overdraft of the Mississippi River Valley Alluvial Aquifer.
A typical tailwater recovery system in the Mississippi Delta is defined for this analysis as one that receives irrigation water from 120 acres and increases irrigation efficiency from 40 to 70 %. Assume the crop requires 1 acre foot of water. At 40 % percent efficiency, 2.5 acre feet (1 foot / 0.4) would have to be applied. At 70 % efficiency, only 1.4 acre feet (1 foot / 0.7) would need to be applied. The increased efficiency saves an acre foot of water per acre. A 120 acre field would have a 120 acre foot savings at $3000 average annual cost; therefore, the water would cost $3000 / 120 or $25 per acre foot. (See table 2) Structural features designed to maximize wildlife benefits can be added at no extra cost. Calculations using groundwater savings of 120 acre feet per tailwater recovery system and the need to replace 100,000 acre feet of water per year were used to predict the need for 833 tailwater recovery systems (100,000 acre feet / 120 acre feet). The installation cost would be $17 million. (See Table 1) Currently, the Delta has the potential to install approximately 6,000 (120 acre watershed) tailwater recovery systems on 720,000 acres of irrigated rice, cotton, corn, and soybeans (acres irrigated by center pivots were not included in these calculations). Tailwater recovery systems would be needed on about one sixth of the current irrigation systems to meet the immediate water conservation goals of the Delta.
On-Farm Water Development The on-farm storage scenario was based on a cut-and-fill reservoir design. In a cut-and-fill reservoir, the excavated materials are used to build up the walls of the reservoir. This allows water to be stored both below ground level and above to the height of the walls improving land use efficiency. The reservoirs were designed to capture precipitation in the non-growing season to be used for irrigation as needed. Required reservoir storage capacity is a function of the following. 1. water requirements of the crops to be grown 2. effective growing season rainfall 3. irrigation method efficiency 4. losses due to evaporation and seepage 5. expected inflow into the reservoir Storage reservoirs serve a dual function as flood control structures. Their effectiveness in flood control depends upon how empty they are when the floodwaters arrive. Reservoirs designed for flood control have an empty volume to catch a flood event mitigating flood effects downstream of the reservoir. Careful watershed planning would indicate where reservoirs should be designed to provide an empty volume for flood control.
A typical storage water reservoir is defined for this analysis as consisting of a storage pond, a pump or pumps, a return delivery system and other associated structures such as water control structures. Reservoirs would be filled to capacity with spring runoff and kept as full as possible with subsequent rainfall events. Water would be used for irrigation as needed or as long as the supply lasted. Pumps would be sized at or near peak runoff rates to maximize capture without requiring large sump areas. Pumps would be high volume low lift types.
Standard NRCS models for drainage area (EFM2) and water budget (RESOP) were used to design some scenarios for typical storage reservoirs. These resulted in a 143 acre feet savings on a reservoir designed to serve 160 acres. Total reservoir cost would be (160 acres * $359 per acre served) $57,400. (See Table 1 and Table 2) The average total annual cost of $9000 with 143 acre feet saved yields a cost of ($9000 / 143) $63 per acre foot. Installation of reservoirs in sufficient numbers to decrease the 100,000 acre foot overdraft would cost $40 million ((100,000 acre feet / 143 acre feet per reservoir) * $57,400 each)).
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Optimizing management with the use of some groundwater could significantly improve water savings and lower cost per acre foot.
Table 1: Costs for tailwater ponds and on-farm water storage reservoirs. 8 Item Unit Unit Cost Storage reservoir Acres served 158 Pipeline for delivery Acre 96 Water control structure Acre 57 Pumping plant Acre 48 Total reservoir cost Acres served $ 359.00
Tailwater recovery system Acres served 11 Pipeline for delivery Acre 51 Water control structure Acre 57 Pumping plant Acre 48 Total tailwater cost Acres served $ 167.00
Table 2: Sample tailwater recovery pond costs and benefits. Watershed Size 40 Acres 120 Acres Total Installation Cost 6,680 20,000 Total Annual Benefits 2,204 6,600 Average Annual Installation Costs 556 1,389 Annual Operation, Maintenance, and Repair Costs 1,020 1,666 Total Annual Costs 1,576 3,055 Annual Benefit to Cost Ratio 1.4:1 2.16:1
Table 3: Sample storage water reservoir costs and benefits. Watershed Size 40 Acres 160 Acres 640 Acres Total Installation Cost 14,400 57,400 230,000 Total Annual Benefits 4,400 13,800 40,400 Average Annual Installation Costs 1,000 4,200 16,700 Annual Operation, Maintenance, and Repair Costs 1,200 4,800 19,200 Total Annual Costs 2,200 9,000 35,900 Annual Benefit to Cost Ratio 2:1 1.5:1 1.1:1
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Sunflower River Sediment Control Meeting water quality standards can be approached from several different viewpoints. The most significant water quality problem in the Delta is total suspended sediment load as discussed in the water quality section of this report. The Sunflower River watershed will be used as an example to demonstrate the resources needed to help solve this problem.
Table 4: Monthly suspended sediment load calculated for the Sunflower River watershed at the town of Sunflower. Sampling site 20 in Figure 4. 1994-1996 Average Monthly Total Actual 1996 Sediment Load at a Monthly Flow Suspended Solids Sediment Load per 100 ppm Water Month Quality Standard* cfs ppm tons tons January 1,320 1,050 112,086 10,675 February 1,660 241 32,353 13,424 March 1,800 1,005 146,295 14,557 April 1,300 800 84,105 10,513 May 1,000 310 25,070 8,087 June 820 476 31,565 6,631 July 500 130 5,257 4,044 August 400 98 3,170 3,235 September 110 182 1,619 890 October 90 313 2,278 728 November 350 200 5,661 2,830 December 1,100 200 17,791 8,896 Annual Total Suspended Sediment 467,251 tons 84,510 tons * MS DEQ Tentative Standard 100 ppm Total Suspended Solids
Stages were measured by a Corps of Engineers stage recorder and converted to flows using the stage- discharge relationship for that site. Sediment concentrations were measured monthly by USDA NRCS as part of the Delta Water Supply Study. Estimated sediment loads per month were calculated using concentrations and monthly average flow rates. The acceptable sediment load, i.e. at the water quality standard, was the monthly and annual sediment load that the river could carry for the given flow and still meet water quality standards.
The Sunflower River is considered to be an agrading channel, the Corps of Engineers estimates that the bottom of the channel has increased approximately 3 feet since the 1960's. This, along with the fact that there were few indications of excessive bank erosion, indicated that the primary sediment inputs were from nonpoint sources, primarily agricultural lands. The Sunflower River at the town of Sunflower could transport 84,510 tons of sediment annually and still meet standards. The estimated annual sediment transported in 1996 was calculated to be 467,251 tons. Therefore, the Sunflower River contained 382,741 tons (467,251 tons - 84,510 tons) of sediment that would need to be removed for the 100 ppm tentative Mississippi Department of Environmental Quality standards to be met.
The Sunflower River watershed represents about one fourth of the total farmed acres in the Delta. Extrapolation results in the determination that 1.5 million tons of sediment would need to be controlled to reach water quality standards for total suspended solids in the Delta. This extrapolation assumes a similarity of land use and land type that is acceptable for this unique area. More detailed calculations will be made as planning continues.
Field monitoring demonstrated that one of the most effective and cost efficient systems to control sediment in Delta farmland involved a combination of permanent pads and levees, water control structures with slotted board risers, a water management plan to pond water in the winter months, and a land management
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plan which included minimum tillage.9 This system reduced sediment loss by 2.25 tons per acre per year at an average cost per acre of approximately $110.00. Treating to remove 1.5 million tons of sediment would involve an estimated 670,000 acres (1.5 million tons/2.25 tons per acre) which would require about $73 million. Practices already in place would lower this dollar amount and all farmed land would not receive this combination of treatments; however, this calculation does provide a working number for a treatment system to meet standards.
Section 3: Environmental Impacts
Environmental impacts on soil from these proposal practices would all be positive. These proposal practices would help maintain soil resources by decreasing erosion. There were no adverse impacts on the soil resource from these proposal practices. Environmental impacts on water from these proposal practices would be positive. Nothing in this proposal would produce long term adverse impacts on water. Major considerations include the following. 1. Any channel work would produce short-term problems with sediment enrichment. Studies done by the Army COE show that sediment loads return to normal when construction is completed. 10 2. The strong statistical correlation between total phosphorus and turbidity and total solids indicates that control of sediment erosion will have significant positive impacts on the physical, esthetic, and chemical water quality in these streams. EPA is planning to implement regulation of water quality standards using Total Maximum Daily Loads (TMDL) for various pollutants. Total nitrogen and total phosphorus would be likely candidates for monitoring in the Delta. 3. Examination of all tissue samples in this study by comparison to established limits did not reveal any significant health risk to people eating fish from local waters in the Mississippi Delta. Nothing in this proposal would produce adverse impacts on air quality. Environmental impacts on plants and animals from these proposal practices would all be positive and far- reaching. The North American Waterfowl Management Plan would benefit from the implementation of conservation practices. This proposed priority area would contribute up to 50,000 acres to the goal of the US Fish and Wildlife Service to provide 91,000,000 duck use days of mallard and northern pintail migration and wintering habitat on private lands. It would also serve as a demonstration model for other areas showing how to integrate wildlife management and sustainable agriculture. Other bird species would benefit from habitat improvements.
Other nongame, including the nongame special attention birds, migratory shorebirds and songbirds, and special concern fish, would significantly benefit from the seasonal impoundment projects and enhancement of existing forested wetlands.
The pallid sturgeon, paddlefish and blue sucker would benefit from water quality improvement. Installation of control structures on agricultural fields would decrease soil erosion and sediment loads in runoff.
Study implementation could ultimately benefit endangered species in the area by helping to return certain habitats to their former condition by installing practices to improve water quality. Species include pondberry, bald eagles, Louisiana black bear, and the pallid sturgeon.
Study implementation would also result in long-term wetland conservation. Wetland benefits would accrue for projects involving control structures for 25-35 years. Conservation of international, national and regional biological diversity would significantly benefit from wetland improvements. The study area contains important forested wetland habitat for a variety of wildlife species, particularly migratory birds. However, habitat quantity and quality has declined due to loss and fragmentation as a result of beaver activity, drainage and land clearing. The U.S. Fish and Wildlife Service has identified the Delta as the area
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of highest concern for game and nongame migratory birds. This proposed program would benefit species diversity on all levels by increasing quantity, quality and distribution of wetlands. Increasing wetland carrying capacity increases its ability to support a greater variety of species and distributing these species over a larger area.
Water quality improvements would benefit species diversity and health in aquatic habitats. Biodiversity would benefit from early and late successional areas provided by forest enhancement that will restore viable representatives of natural wetland communities. The proposal would contribute to efforts of Wetland Reserve Program and state and federal acquisition programs. Restoration of wetland hydrology and enhancement of existing forested wetlands on widely distributed private land would help decrease habitat fragmentation between permanently protected state and federal lands. This would permit greater dispersal of plant and animal species and expand the sphere of influence of publicly managed habitats on their distribution and abundance. The proposal would also work toward increasing public awareness of the importance of biodiversity.
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References Cited
1 Pote, J.W., C.L. Wax, and C.S. Tucker, 1988. Water in Catfish Production: Sources, uses and conservation. Special Bulletin 88-3, Mississippi Agricultural and Forestry Experiment Station, 16 pp. 2 YMD Joint Water Management District, 1996. Water Use Permit Database. YMD, 384B Stoneville Road, Stoneville, MS 38776 3 Massey, Bobby J., Johnny Chism and Paul Rodrigue, 1987, Irrigation water management year end report, USDA SCS, Area I, Mississippi 4 United States Environmental Protection Agency, 1993. The Watershed Protection Approach: Annual Report 1992. EPA840-S-93-001 5Comerford, N.B., Neary, D.G. and Mansell, R.S, 1992. The effectiveness of buffer strips for ameliorating off-site transport of sediment, nutrients, and pesticides from silvicultural operations. NCASI Technical Bulletin No. 631. National Council of the Paper Industry for Air and Stream Improvement, New York, NY. 48 pp. 6Joslin, J.D. and Schoenholtz, S.H., In press. Measuring the environmental effects of converting cropland to short-rotation woody crops: A research approach. New Zealand Journal of Forestry 7Stanturf, J.A., Schweitzer, C.J., and Gardiner, E.S., In press. Afforestation of marginal agricultural land in the Lower Mississippi Alluvial Valley, USA Silva Fennica. 8 Supplied by the USDA NRCS South Central Water Management Center, Little Rock, Arkansas, Michael Sullivan, Director. 9Manley, Scott W. 1996. Ecological and agricultural values of winter-flooded rice fields in Mississippi. 1995-1996 Annual Report. Mississippi State University, Department of Wildlife and Fisheries. 10 US Army Corps of Engineers, Vicksburg District, 1997, Flood Control, Mississippi River & Tributaries; Mississippi Delta, Mississippi, Feasibility Report Draft, Volume IV Appendix 10
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Appendix A: Cost of Conservation Practices
Practice Unit Type State Average Unit Cost* 1. Seasonal residue management acre 5.00 2. Structures for water control number small site each 1,200 large site each 2,700 3. Buffer Zones Riparian Forest Buffer tree planting - hardwoods & shrubs acre 140.00 Filter strips acre 160.00 Grass waterways number establish vegetation acre 160.00 earthwork cu yd 1.33 4. Landforming & establishing permanent pads & levees cu yd 1.00 5. Tailwater recovery ponds number earthwork for water storage acre ft 2,100 permanently installed pumping plant gpm 4.00 6. Cost - sharing for conversion of surface irrigation acre 8.50 systems to sprinkler irrigation system 7. Tree planting - hardwoods & shrubs acre 140.00 8. Irrigation storage reservoirs number establish vegetation acre 160.00 earthwork cu yd 1.33 9. Agrichemical mixing centers sq. ft 18.50 10. Decommissioning of abandoned wells number 800 *All costs are in $ and are compiled from programs administered by NRCS in Mississippi.
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Appendix B: Assumptions used for Economic Evaluation 1. Interest 7 % 2. 50 year evaluation 3. Amortization factor was 0.07246 4. Future without project would deplete the Mississippi River Alluvial Aquifer to the extent that either no pumping could occur or the expense of pumping would be prohibitive. 5. In the future without project scenario, a) All rice would be converted to soybeans. b) All soybeans and cotton would be nonirrigated. c) Catfish production would, for all practical purposes, be eliminated. 6. Cotton ground was assumed to be 60 % irrigated, 40 % nonirrigated. 7. Soybean ground was assumed to be 25 % irrigated, 75 % nonirrigated. 8. Total cropland was assumed to be 45 % irrigated and 55 % nonirrigated. 9. Reported net returns on catfish ranged from $500 to $1000 per acre. The information came from interviews with farmers, field office personnel, and the Mississippi Cooperative Extension Service. $750 was used to calculate benefits for this study.
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