CECW-PE 13 September 1999

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1. Administration Support. The Los Angeles District presented a project proposal for North Scottsdale, Arizona, in a 1996 reconnaissance report. For that project, about 95 percent of the benefits claimed were related to potential savings in future FEMA required floodproofing compliance costs. In that case, the Assistant Secretary of the Army (Civil Works) (ASA(CW)) determined that the Army would not support a Federal flood damage reduction project for the North Scottsdale area. The ASA(CW) concluded that there was no basis for Federal financing of a project that is within the capability of others who would be required to provide protection as the area develops. In the current case, about 85 percent of the benefits claimed for the overall plan are related to potential savings in future FEMA required floodproofing compliance costs. For economic evaluation Zone D, 100 percent of the benefits forecasted are attributable to future development. Because of this past similar case, CESPL should inform the prospective non-Federal sponsor that the project proposal might not conform to current Department of Army policy for support and Federal funding.

District Response: In August 1997 the District requested clarification of the status of the reduction in future flood proofing benefits. By 2^nd Endorsement to the District’s memorandum (CECW-PE, dated 3 October 1997) Headquarters acknowledged that "…the feasibility study was initiated on the basis of Corps support for a Federal flood control project for this area..". The response concluded "…that projects of this nature would most likely receive a low budget priority, and it is unlikely that funding for construction of a project that relies primarily on benefits from future development for project justification would be included in future budget requests." The guidance suggests that a report identifying a Federal interest with a low budget priority would be acceptable. The sponsor has been previously notified of this guidance.

Discussion: Current policy allows the NED plan to be formulated to protect existing development and vacant property that is interspersed with existing development. All project benefits, including land development benefits for interspersed vacant property, will be included for project formulation and justification. The NED plan may provide for the protection of vacant property that is not interspersed with existing development if it can be demonstrated that the vacant property would be developed without the project and benefits are based on savings in flood proofing costs or reduction in damages to future development. However, since the strategy is to support Federal participation where the primary objective is flood damage reduction to existing development, projects of this nature would most likely receive a low budget priority. Thus, it is unlikely that funding for construction of a project that relies primarily on benefits from future development for project justification would be included in future budget requests. The district response correctly describes the direction that the district is to take in completing the report in accordance with current policy. This policy on benefits from future development was established after the reconnaissance study determined that there was a potential Federal interest and after the initiation of the cost-shared feasibility phase. The sponsor expressed concern over the change in policy and expressed interest in a reevaluation of the policy to allow recommendation of a project, consistent with the reconnaissance phase findings that formed the basis for the initiation of the cost-shared study. If the sponsor and the district want to pursue a reevaluation of the policy, a rationale/options paper will need to be developed in support thereof.

Action Required: The district will proceed to complete the draft report, identify the NED plan, NER plan and optimum plan that are in the Federal interest. A recommendation for authorization will not be proposed because of the low budget priority outputs. If desired, the sponsor and field may request a Washington-level reevaluation of the policy as it applies to this project.

2. Incremental Justification of Separable Features.

a. Morongo Wash/Long Canyon Diversion Features. The selected plan includes structures designed to capture flood flows from Morongo Wash and Long Canyon and to convey these flows to the Whitewater River. These features appear to be hydologically and economically separable from the remainder of the preferred plan identified in the AFB materials. The AFB material mentions the possibility that this plan segment may be a separable feature (page IV-8 of the Main Report); however, does not describe an attendant incremental justification process. Only increments that provide net NED benefits after accounting for appropriate mitigation costs are to be included in the NED or optimal combination NED/NER plans (ER 1105-2-100, paragraph 5-7 b.) Based on rough calculations, this $24.1 million separable increment of the plan may not be justified. An incremental analysis should be performed. The results of such incremental analysis should be included in the feasibility report to justify inclusion of the features in both the NED and the preferred NED/NEQ plans.

District Response: Concur. The report will be modified to include an analysis of separability and incremental justification as they pertain to the Morongo Wash/Long Canyon diversion feature.

Discussion: The district explained that the features are not separable because a plan to address down fan flooding must also accommodate flows from Long Canyon. However, it was recognized that the particular plan chosen for accommodating these flows must be incrementally justified. The district clarified that the Morongo Wash/Long Canyon diversion features were not a separable element since the formulation of other features is dependent upon their existence. The areas are not hydraulically separable. The district agreed that an incremental justification will be performed and presented in the report.

Action Required: The draft report will be revised to present an incremental analysis for the Morongo Wash/Long Canyon diversion features and explain that they are not hydraulically separable.

b. Pushawalla Canyon Levee Extension. This feature of the selected plan appears to be hydologically and economically separable. An incremental analysis should be performed. The results of such incremental analysis should be included in the feasibility report to justify inclusion of the features in both the NED and the preferred NED/NEQ plans.

District Response: Concur. Benefits separably associated with the Pushawalla Canyon levee extension, along with the resulting BCRs, are displayed in Table 26 on page V-46 of the Main report. The levee extension is incrementally justified with a BCR of 1.52 and the plan for the project area west of the preserve remains justified with a BCR of 1.22. The discussion in report will be expanded.

Discussion: The district confirmed that the Pushawalla Canyon levee extension is a separable element and the analysis, although not specifically identified with the Pushawalla Canyon levee extension, is contained in the report.

Action Required: The draft report will be revised to clearly identify the incremental analysis for the Pushawalla Canyon levee extension.

3. Flood Control Features for Small Drainage Basins. The flood damage reduction features north of Thousand Palms consists of a system of runoff collectors, laterals, and a main conveyance channel. In many respects this system resembles the typical storm water control system routinely used by cities and towns. As cited in ER 1165-2-21, in urban or urbanizing areas, provision of a basic drainage system to collect and convey the local runoff to a stream is a non-Federal responsibility. Water damage problems may be addressed under Federal flood control authorities downstream from the point where the flood discharge is greater than 800 cubic feet per second for the 10-percent-chance-exceedance flood. Drainage areas of less than 1.5 square miles shall be assumed to lack adequate discharge to meet the above criteria. Most of the alluvial fan drainage areas north of Thousand Palms do not appear to satisfy these criteria for Federal participation. The feasibility report should recognize this limitation on Federal participation in the proposed storm water collector and conveyance features of the flood control system. The draft feasibility report will need to establish the basis for a policy exception if these features are to be included as part the Federal plan.

District Response: Concur. It is important to stress that reliable flood protection on alluvial fans requires what the Federal Emergency Management Agency terms a "whole fan solution". Therefore, the location of the debris basins and collector channels conveying the runoff to the main channel is an absolute necessity. It is not possible to collect flows emanating from the canyons lower on the alluvial fans, rather, it was paramount to intercept flows at the apex of the fans, at the mouth of the canyons. In addition, these feature were designed to provide significant environmental outputs by preserving, as much as possible, natural fluvial delivery of appropriately sized sediment to the wind corridor west of the preserve. The report will be modified to present a discussion of the limitations of Federal participation in small drainage areas as they apply to this project.

Discussion: FEMA requirements of individual developers were discussed which include protection from the concentrated 100-year flood flows and no significant alteration in down fan impacts. Since the flood flows can travel in many directions, the whole fan must be controlled for the area to be removed from the FEMA flood plain. The most efficient point of control is at the fan head. Dr. Li pointed out that in an area of commingled fans you can not deal with only one or two fans. Another issue raised was that of interior drainage and whether the district was confident that all interior drainage requirements have been addressed. Dr Li indicated that local infrastructure improvements would be adequate to convey the volume of water that would runoff the fan area. No additional improvements would be required to address residual runoff on the fan above the typical infrastructure improvements provided by local developers.

With regards to the proposed project’s consistency with the requirements of ER 1165-2-21, Flood Damage Reduction Measures in Urban Areas, the South Pacific Division has indicated that the project would be consistent with the requirements of regulation. The proposed project is designed to modify the natural waterway to reduce flood damages in the future with project urban area from major storms and flows from the canyons onto the urbanizing area of the alluvial fan. The proposed project does not address problems associated with runoff emanating from the future urbanized fan. Future urban development in the fan will be required to provided appropriate local infrastructure improvements to address runoff from the urban area and ensure that flows are conveyed to the proposed flood control channels.

The policy in the ER relates to the differentiation between storm sewer systems and flood control systems. This is a differentiation that, on the surface is not directly applicable to the canyons that empty onto the alluvial fan. The portion of the policy that would be applied, simply stated, is that flood damage prevention may be addressed under the flood control authorities, downstream from the point where the flood discharge is greater than 800 cfs for the 10-percent flood. Division Engineers are, however, authorized to grant exceptions to the 800 cfs rule whenever the 1 percent flood discharge exceeds 1800 cfs, and when there are conditions in the drainage area that result in a hydrologic disparity between the 10- and 1- percent flood events.

In the case of the Whitewater River study, a number of individual canyons empty onto the alluvial fan, thereby creating the flood problem. The Canyon at concentration point CP 13 meets the 1-percent flow criteria. The adjacent canyons at concentration points CP8, CP9, CP10, CP11 and CP14 do not convey the flow to meet the 1- percent flood flow criteria. In all cases, however, when the combined flows from one canyon plus an adjacent canyon are considered, the 1-percent flood flow criteria is met. Thus the conditions are met wherever there are combined overflows. The geographic limit of the combined flows, plus the area below concentration point CP13, would then be the limit to which economic benefits could be claimed for justification.

The presence of extremely pervious sand in the drainage area limits the discharges for the 10-percent flood, without proportionately reducing the discharges of larger floods, such as the 1-percent flood. Since there are conditions that result in a hydrologic disparity between the 10- and 1- percent flood events and since the combined overflows meet the 1800 cfs requirement for the 1-percent flood event, the Division Engineer is authorized to grant an exception to the 800 cfs rule.

As indicated in Paragraph 7.a.(4), the ER recognizes that flood reduction measures, such as dams, diversions or the measures that are proposed in the Whitewater alternatives, may be located upstream of the particular point where the hydrologic criteria are met, if economically justified by benefits derived within the area that does qualify under the hydrologic criteria. The proposed measures in the Whitewater alternatives that are located at the concentration points CP8, CP9, CP10, CP11 and CP14, are within policy as they are economically justified by benefits derived from areas subject to combined flows.

As indicated in Paragraph 7.a.(1) of the ER, those areas which receive runoff from land outside the urban area are not to be evaluated using the 1.5 square mile drainage area criteria. Since the flows from the canyons do not originate in an urban area, use of the criteria is not appropriate. Even if the criteria were to be applied, similar to the description of the flow criteria above, all areas that are subject to combined flows would meet the 1.5 square mile drainage area criteria.

Action Required: The draft report will describe the rationale for Federal participation in the channels, giving full consideration to the policy contained in ER 1165-2-21. The district will also request a formal waiver of the 800-cfs criteria from the South Pacific Division. The report will include a clear discussion of the residual local drainage and describe any additional improvements that may be required over and above those that are normally required for local development. These additional improvements would be included in the project as associated costs.

4. Beneficiary Profile. The AFB document includes only a minimal discussion of real estate. There is concern that windfall benefits could accrue to a few beneficiaries. There is no indication in the briefing materials that there are many owners of the undeveloped land in the areas that would be protected from flooding. Paragraph 13-10.c of EP 1165-2-1 describes the need for special cost sharing in situations where windfall benefits of "unconscionable" magnitude are received by a relative few project beneficiaries. CESPL should determine the number of affected landowners and address the issue of whether special cost sharing should be recommended.

District Response: Concur. The report will be modified to clearly demonstrate multiple ownership. There is currently only one large landowner. This individual’s property is located in what would become the floodway/corridor. Thus, there would be no landowners reaping a windfall.

Discussion: The response was discussed and it was agreed that the report should include the number of owners and highlight any large parcels.

Action Required: The number of owners and parcel sizes will be included in the draft report.

a. Estimate of Per-Acre FEMA Compliance Costs. Per-acre FEMA compliance cost estimates are simply presented in a table on page 15 of the economic appendix without explanation of how the costs were derived. The estimates range from $79,000 per acre for a 10-acre development to $16,000 per acre for a 640-acre development. The draft report should provide details of the derivation of these costs and supporting documentation that would lead to an independent conclusion that the estimates are reasonable.

District Response: Concur. Flood proofing costs by parcel size were developed in-house based upon concepts that meet FEMA flood proofing requirements. The report will be revised to include typical designs and back-up materials for the costs.

Discussion: Three types of flood proofing designs were used to estimate the flood proofing benefits.

Action Required: The draft report will include details of the alternative flood proofing designs considered and cost estimates that were developed to estimate the savings in flood proofing benefits.

b. Depth-Damage Relationships. Per ER 1105-2-100, Table 2-1, paragraph 3.b, the feasibility report should include more complete information on the source of the depth-damage relationships used, along with the damage percentages applied per foot of inundation depth.

District Response: Concur. Standard FEMA depth/damage curves were used. The report will be revised with additional information.

Discussion: The district explained that there is inadequate data to derive specific depth /damage relationships for this study area. Structures in the area are not unique and the FEMA curves used were determined to be appropriate in similar study areas

Action Required: The justification for the use of the FEMA curves, provided in the discussion, will be included in the draft report.

c. Value of Contents. The Economics Appendix states that the content value of residential structures was assumed to be 50 percent of the replacement value less depreciation. The basis for this assumption should be discussed in the draft report.

District Response: Concur. Content ratios were based upon prior Corps studies for the southwestern U.S. performed by the LA District. A detailed content survey was not performed for this study, since damages to existing development are small relative to the savings in future flood proofing expenditures. This information will be presented in the report.

Discussion: Content ratios used in prior studies were used for this effort, since there was not enough data to derive specific relationships. There is nothing unique to the study area. The prior studies will be referenced in the draft report.

Action Required: The prior studies that used the content ratios will be referenced in the draft report.

d. Value of Manufactured Homes. The majority of the existing residences to be protected from flooding are classified as manufactured homes. Based on data in the Economic Appendix, the average depreciated structure value is about $52,453. This may be at the high end of the value range for manufactured homes, especially those that may have been in use for a number of years. The feasibility report should include information supporting the adoption of this value.

District Response: Concur. In the area west of the Preserve, the structure value per square foot for manufactured housing comes to about $39, which falls within the average/good range for manufactured housing in Marshall & Swift guides. The somewhat large value per structure stems from the fact that many of these manufactured homes are fairly large (average of over 1,300 square feet). The square footage of these structures was based upon a field survey and real estate assessor's data. The feasibility report will include information supporting the adoption of this value.

Discussion: The information in the response was accepted.

Action Required: The information in the response will be included in the draft report.

a. Environmental Restoration. The district is proposing an environmental restoration project purpose that consists entirely of land acquisition (approximately 587 acres and $3 million cost). The proposal has no association with the engineering expertise of the Corps or the hydrologic regime of the study area as required by ER 1105-2-100, paragraph 4-38(b). Without these components, the acquisition of land does not comply with policy for environmental restoration projects. The district should present any information as to how the wind corridor meets Corps policy.

District Response: Non-concur as to the lack of association with Corps engineering expertise. Concur that the report should be modified to reflect the following: This project’s environmental objective is to maintain the fluvial and aeolian transport mechanisms that provide habitat for several sensitive species, while providing flood protection to surrounding areas. Fluvial and aeolian transport are both necessary components of the blowsand ecosystem. Floodwaters provide new supplies of sediment to the wind corridor, and activate new dune systems by cutting channels and removing layers of surface "armor" (small cobbles and other unsuitable material). The wind then transports habitat quality blowsand to the Preserve.

The proposed channels, levees, and approximate 400-acre floodway will maintain the fluvial component of this ecosystem, and protect 40% of the sand deposits on the wind corridor. However, without protecting additional sand supplies, the Preserve will eventually degrade. Indio Hills sand, alone, is not sufficient to replenish the Preserve’s blowsand. Although the proposed 700-acre wind corridor/floodway would protect only 70% of the sand supply, this amount should be sufficient to maintain the Preserve’s viability and habitat values for the life of the project. It is hoped that the remaining area of prime wind corridor would be purchased by other agencies as part of a multi-species habitat conservation plan (HCP). These agencies, however, do not currently have funding in place to purchase the entire 700-acre wind corridor/floodway, and the flowage easements from the canyons.

We realize the Corps is not normally authorized to purchase land solely for preservation. However, we believe this project is supported by several sections of EP 1165-2-1. First, Section 19-3 states that Corps activities in ecosystem restoration and protection will concentrate on engineering solutions. It further states that the Corps’ principal focus will be on ecological resources and processes that are directly dependent on the hydrologic regime of the ecosystem. This project’s "engineered" solution for maintaining fluvial transport would eventually become ineffective, unless sufficient wind corridor sand supplies are also protected. A fully functioning blowsand ecosystem is directly dependent on hydrologic (fluvial transport) processes, which would be maintained through engineering solutions, and aeolian processes, which would be maintained through land purchase.

Sections 19-3, 19-4, and 19-6 promote coordination and collaboration with other agencies to achieve restoration goals. This project has been fully coordinated and designed to promote a multi-agency effort to establish a multi-species HCP. The goal of the HCP is to preserve large areas of open space that provide habitat for state and Federally listed sensitive species. It is likely, however, that without the Corps’ support, many critical areas will develop before the necessary funds can be obtained.

Section 19-4 also provides guidance for using an ecosystem approach to planning. "The ecosystem approach consists of restoring and/or protecting the structure and function of an ecosystem, or parts thereof, recognizing that all its components are interrelated." As previously stated, the blowsand ecosystem can only be sustained intact through preservation of the wind corridor. Future development, if it occurs as predicted, would cover sand deposits, block aeolian and fluvial transport, and either fragment or completely destroy existing resources on the wind corridor. With this project, the Corps has an opportunity to ensure long-term viability of the blowsand ecosystem. This viability cannot currently be assured through other regulatory or protection efforts.

Section 306 of WRDA 1990 (Public Law 101-640) authorizes the Secretary of the Army to include environmental protection (i.e., measures undertaken to protect and preserve elements of an ecosystem’s structure and functions against degradation) as one of the primary missions of the Corps.

Finally, Section 7 of the Endangered Species Act requires agencies to undertake affirmative programs for the conservation of listed species. The proposed project will conserve approximately 200 acres of designated critical habitat for the Coachella Valley fringe-toed lizard, above and beyond the lands that would be set aside for flood control and mitigation. This area is also potentially occupied by other Federally listed and proposed species, including the Coachella Valley milkvetch and the desert tortoise.

Discussion: The case was made that a corridor smaller than 700 acres may be inadequate to sustain the preserve. Acquisition of the 700 acres is required for a complete plan to address the restoration outputs. The district indicated that the nexus with Corps expertise is the hydraulic delivery of sediment to preserve the fringe-toed lizard habitat. And once that nexus is established the additional acreage is required to meet the minimum needed for preservation and make the project complete.

HQUSACE representatives indicated that the separable restoration lands did not fit the Corps policy regarding land acquisition for restoration. Therefore, the cost-shared plan would focus only on those features that support the flood control purpose and associated mitigation. The separable lands (246 acres) for restoration would be in the Federal interest but not the Corps interest. The addition of these lands would be part of an overall plan that would not include Corps participation. There are currently other Federal and non-Federal programs that can address the acquisition of these separable restoration lands.

The US Fish and Wildlife Service representatives indicated that they could not support the project presented in the pre-conference documentation. The plan would likely result in a jeopardy opinion since they are not convinced that the plan would provide adequate sands to the preserve. Concern was also expressed with flooding of the Preserve. A major up-fan portion of the study area is within the designated critical habitat zone.

Action Required: The acreages and land costs for mitigation, the floodway and separable lands for restoration will be specified in the report. The cost apportionment to the Corps will not include separable restoration lands. Page 6-5 of the EIS will be modified to clarify what the $20,000 per acre cost represents. The district, sponsor, and the US Fish and Wildlife Service will meet to investigate an additional alternative(s) that would address the Service’s concern and provide adequate sands to the preserve. This alternative may be in the overall Federal interest and would include some elements that would be implemented through the authorities of other Federal agencies.

b. Mitigation for Indirect Impacts. The district is recommending the acquisition of land to protect a wind corridor that supplies sand to maintain endangered species habitat in the preserves. The Coachella valley fringed-toed lizard preserves were established as part of a Habitat Conservation Plan developed by the county and local governments and the FWS under Section 10 of the Endangered Species Act. As a result of future development in the "wind corridor," transport of sand to the dune areas is predicted to be reduced. As development in the wind corridor is not a direct impact of the flood control project but rather an indirect impact governed by the land-use planning authorities of state, county and local governments, mitigation by the Corps is not in accordance with Corps policy. The district must not propose mitigation for the potential indirect impacts of the proposed project plan.

District Response: Concur. The document will be re-written to clarify that the proposed mitigation is to replace habitat values lost through direct, construction-related impacts to vegetation and other sensitive habitats. The first step in mitigation was to avoid or minimize impacts to sensitive resources, as much as possible. The Pushawalla levee and the Long Canyon diversion, for instance, were both re-designed to avoid creosote hummocks and wildlife corridors. Detention basins and transition levees will be placed low enough in the canyon mouths to avoid most of the desert wash vegetation. For unavoidable impacts, the document evaluated both in-kind mitigation (replacement of desert wash vegetation and creosote hummocks), and out-of-kind mitigation (long-term protection of sensitive resources). Desert wash vegetation is difficult to establish and maintain, and creosote hummocks may be impossible to artificially reproduce. Efforts to provide in-kind mitigation, whether off-site or on-site, may well be unsuccessful. Resource agencies, therefore, have supported the concept of using mitigation funds (based on estimated costs for in-kind replacement) to purchase critical habitat on the wind corridor. From an ecosystem perspective, this would provide greater habitat value for multiple species, including Federally listed species.

Discussion: The district must not propose mitigation for any potential indirect impacts of the proposed project plan. Acquisition of lands for restoration, either by the U.S. Fish and Wildlife Service or the Corps is an action alternative and should not be included in the evaluation of no action. Significant threat to the habitat from developmental pressures would be the basis for the justification of acquisition. The biological assessment for the proposed plan has been completed but will require modification if the plan is reformulated as a result of proposed meetings between the Corps, local sponsor, Riverside County and the U.S. Fish and Wildlife Service. All parties will meet within the week to formulate an alternative that includes acquisition of lands for ecosystem restoration through the programs of other interests. Corps will establish a Federal interest in the overall plan and will identify the scope of the Corps interest.

Action Required: The District will not propose mitigation for indirect impacts of the proposed project.

c. Impact Area of the Flood Control Project. The total mitigation acreage contained in Table 6-1 on page 6-9 is 113 acres for the selected plan with 587 acres assigned to the "restoration" category. Table 6-3 on page 6-11 states that some of this acreage will be used for flood control to naturally convey flood flows. The district should review the real estate requirements for the flood control project to be sure that all real estate requirements have been included in the flood control project description.

District Response: Concur. The report will be modified to clearly present the portions of the area identified as the wind corridor which are required as floodway and mitigation. Note that the portion of the wind corridor required for flood control purposes was included in the flood control cost total (not the restoration cost total).

Discussion: This comment was addressed during the discussion of Comment 6.a.

Action Required: The acreages and land costs for mitigation, the floodway and separable lands for restoration will be specified in the report. The cost apportionment to the Corps will not include separable restoration lands that are not required for the implementation of other restoration measures.

d. Table 6-1, Draft EIS/EIR. Impact 6 (Cultural Resources) and Impact 7 (HTRW) on page 6-8 are not mitigation as defined in ER 1105-2-100, paragraphs 7-35. The study effort is not to the point of developing any cultural resources mitigation in accordance with ER 1105-2-100, Section VIII. If remediation of HTRW is required, the cost should not be included as part of the project mitigation total (MCACES 06 account). HTRW evaluations should follow the guidance provided by ER 1165-2-132.

District Response: Concur. The document will be revised to differentiate between habitat mitigation and other commitments to address cultural resources and HTRW issues. HTRW remediation costs have not been identified, and were not included as part of the mitigation total. Referenced guidance documents will be reviewed, and HTRW evaluations will be conducted in accordance with ER 1165-2-132.

Discussion: The response was discussed and the draft report will be modified in accordance with the response.

Action Required: The draft report will be revised to differentiate between habitat mitigation and other commitments to address cultural resources and HTRW issues. HTRW evaluations will be conducted in accordance with ER 1165-2-132.

e. Nomenclature. The district presents an NER plan as described in ER 1105-2-100, Chapter 5 (see page 5-11). However, the document introduces a new and confusing acronym by defining an NEQ plan (rather than an EQ plan). The standard P&G and ER 1105-2-100 terminology should be used.

District Response: Concur. References to "NEQ" plan will be changed to "NER" plan. (Note that ER 1105-2-100 refers to "NEQ" outputs (e.g., in para. 5-11 (d)), as well as "NER" outputs).

Discussion: There was universal support to limit and simplify the nomenclature. The report will reflect "ecosystem restoration" as a purpose, with the plan that best addresses this purpose as the NER Plan. While the formulation of the plan may include actions to support the preserve by other Federal and non-Federal agencies, the nomenclature will be restricted to the traditional context that can be used for cost apportionment and allocation of the Corps portion of what may be a multi-agency project.

Action Required: The terminology will be revised. If there are separable costs identified for ecosystem restoration, then there may be an NER plan. The district will ensure that usage properly reflects cost sharing procedures.

f. Flood Impacts on the Preserve. The recommended plan includes conveyance features to capture flood flows from the alluvial fans and release them into the Coachella Valley Preserve. Both the report and EIS are silent regarding the introduction of large attenuated discharges into the fragile dune habitat of the Preserve. The draft feasibility report should address the environmental effects of the altered hydrology on the Preserve.

District Response: Concur. Concerns have also been raised about the possibility of increased erosion of the sand dunes and hummocks that form the lizard habitat within the Preserve. A key objective of the recommended plan is to maximize the fluvial transport of blowsand-size sediment to the wind corridor upwind of the Preserve. In order to achieve this objective, flows from CP 8, 9, 10, and 13 would be collected and diverted to a disposal point in the corridor over a mile upwind of the Preserve boundary. An energy dissipater would be provided at the terminus of the E3 diversion channel, as well as at the end of the J and L channels. The dissipaters would greatly reduce the flow velocities and depths, spread the flow out onto the alluvial fan, and induce deposition of the fluvially-transported sediment on the wind corridor. As the flows spread out, small natural channels would form beyond the deltas of deposited sediment, and the flow conditions further downstream would be essentially the same as would be typically found on any natural alluvial fan. The initial flow direction would be to the southeast. However, the natural ground slope shifts to a more southerly direction further downstream. At the western boundary of the Preserve, the general ground slope is to the south - southwest. As a result, the diverted flows would be forced up against the LV1 diversion levee. The flows would then be conveyed in a relatively narrow path against the northern side of the LV2 diversion levee along the southern boundary of the Preserve. The flows would be discharged at an adequate point of disposal beyond the Preserve boundary at the downstream end of the LV3 diversion levee. With the recommended plan, only flows from CP 12 and 15 would be diverted directly into the north end of the Preserve along the LV4 levee. However, the combined 100-year discharge from these two small tributaries is only about 8% of the 100-year discharge from Thousand Palms Canyon immediately to the east. The impact of the additional flow would therefore be insignificant compared to without-project conditions. In short, the recommended plan would convey most of the diverted flows around the southern boundary of the Preserve, and the remaining diverted flows would be an insignificant increase of the without-project flows. Consequently, the recommended plan would cause no increase in erosion of the sand dunes and hummocks in the Preserve. The report will be modified to include a complete discussion of this issue.

Discussion: The response was discussed and the evaluations indicate that there would be insignificant increases in the flows. The district will continue to coordinate with the U.S. Fish and Wildlife Service and other owners to further address this issue.

Action Required: The draft report will be modified to include the information that is presented in the response. The District will continue to coordinate with FWS and other owners to address any questions regarding discharges from the conveyance features.

7. Without-Project Land Development Assumptions. Several sections of the briefing material state an assumption that future development in flood-prone areas will occur regardless of whether a Federal flood control project is implemented. This assumption establishes the basic rationale for evaluation of benefits. The draft EIS notes that development in the area upwind of the Coachella Valley Preserve will have a deleterious impact on sensitive species dependent on windblown sand habitats in the study area. The recommended plan includes purchase of a large tract of this land to assure that the source of wind-blown sand into the Preserve would be protected. It is likely that, in the absence of a Federal project, non-Federal interests would also be subject to similar habitat protection or mitigation requirements. It is probable that all large-scale development upwind of the Coachella Valley Preserve will be required to implement measures to mitigate impacts to endangered or threatened species. These measures could place portions of the upwind area off-limits to development in the without-project condition. The forecasts and assumptions presented in the feasibility report should be adjusted to recognize these aspects of the most probable future without-project condition.

District Response: Non-Concur. Corps development projects were based on forecasts provided by Riverside County, Coachella Valley Water District (CVWD), Coachella Valley Association of Governments (CVAG), coordination with the Nature Conservancy, utilization of real estate data bases, empirical observation and developer inquiries to both the Corps and CVWD. These development forecasts are in accordance with development densities identified in the Habitat Conservation Plan (HCP), which dates to 1985.

The U.S. Fish and Wildlife Service has stated that the HCP gives them the authority to control development west of the Preserve. Development has, in fact, been ongoing since that date, and the Service has not invoked the HCP to stop any development to date. Furthermore, analysis of the HCP by Corps legal staff indicates that the HCP provides no solid basis for restricting development west of the Preserve. Individual developments are under no obligation to mitigate for impacts from their developments, particularly if they are not located in the blowsand corridor. It is the collective opinion of the local jurisdictions that establishment of the Preserve in the first place mitigated for any future developments in the Valley. Riverside County has changed the zoning for the region since the 1985 plan. Although it provides for some additional open space in the corridor area, it also has increased densities in some other areas.

Discussion: This item was discussed in conjunction with the discussions of Comment 6.a.

The U.S. Fish and Wildlife Service desires that the portions of the study area that are designated as critical habitat be preserved, and has been working and will be continuing to work with the County to resolve zoning issues. While the study is consistent with existing and historic zoning, there is concern by the Fish and Wildlife Service that the County has not met the requirements of the HCP. The Service indicated that the HCP would support the present zoning densities only with flood protection. While this flood protection is not in place, the District’s without project condition projects that this flood protection would be provided by individual developers. To preclude adverse impacts from development, the U.S. Fish and Wildlife Service is developing plans to purchase areas of the fan that are within the critical habitat zone. The Service indicated that there is presently approximately $3.6 million of Federal and non-Federal funds available for this purpose. This authority will be included in the plan reformulation, discussed above in the action item for Comment 6.a.

Action Required: The district will continue to coordinate with the County and the U.S. Fish and Wildlife Service in an effort to clarify the basis for establishing future patterns of development.

10. Risk and Uncertainty. The draft report displays a completed risk and uncertainty analysis with some information about risk variables. The degree of uncertainty regarding the engineering and the economic performance of the recommended plan should be described in the draft report in probabilistic terms. ER 1105-2-100, paragraph 5-19 and EP 1165-2-1, paragraph 13-5 contain guidance that can be used to describe the risk assessment results. Also, describe the meaning and the use of the term "0.5 convergence threshold."

District Response: Concur. Since savings in future flood proofing expenditures is the primary benefit category for this study, this category was the focus of the R&U analysis. The Economic development model included several variables, such as study area population/development growth rates, flood proofing costs and development sizes. It was assumed that any plan that would be developed by the Corps would meet FEMA's criteria for a FIRM map revision. Model simulations were run using the Palisade @Risk program with a 0.5% convergence threshold. This means that the program continues performing simulations until the fluctuations in the mean values of the input and output variables are less than 0.5% of the mean value with each simulation. The report will be modified to include this information.

Discussion: The Corps needs to assure that the proposed project would meet the negotiated reliability requirements for a FIRM map revision. To do this, the report will need to include a reliability table based on hydraulic and hydrologic uncertainty.

Action Required: A table that demonstrates the reliability of the proposed project will be included in the report.

9. Non-Federal Sponsor Letter. The District should obtain a letter from the non-Federal sponsor indicating that they have reviewed the draft feasibility report and support the recommended plan. The letter should indicate an understanding of the non-Federal responsibilities and required financial commitment for initial construction, periodic transport of sand to distribution points, project monitoring, OMRR&R, and LERRD. The letter should also briefly describe the source of non-Federal funding.

District Response: Concur. The letter shall be obtained from the sponsor and included in the final report.

Action Required: A letter of intent from the local sponsor will be included with the final report. If the letter is available before the release of the draft report, it will also be included.

10. Real Estate. The AFB document contains little real estate information. CESPL has not identified any real estate issues for discussion at the AFB. The AFB document states that the "real estate cost for project rights-of-way is a significant portion of the total project costs." Consequently, it is particularly important that a comprehensive Real Estate Plan be prepared in accordance with Chapter 12 to ER 405-1-12 for the draft feasibility report.

District Response: District requests permission to release the draft feasibility report without a completed Real Estate Plan.

Discussion: Current policy is that a draft of the Real Estate Plan will be included with the draft report. The district Planning and Real Estate offices will coordinate the requirements for the draft Real Estate Plan.

Action Required: A draft Real Estate Plan will be included with the draft report.

11. Documentation Of Technical And Legal Review. The AFB material does not include documentation of independent technical review and certification that technical and legal reviews of the report have been completed. Certification of technical and legal reviews and documentation of significant issues, possible impact, and resolution should be provided with the draft report per EC 1165-2-203.

District Response: Concur. Documentation of the completion of Independent Technical Review of prior products was forwarded subsequent to submission of the AFB package. Technical review of the AFB package has been completed and certification will be provided following the AFB conference.

Discussion: CESPD guidance for the certification of independent technical review requires that the responsible functional chief (in this case the chief of Planning) certify the technical adequacy of the draft report. This individual is responsible for the overall quality of the product. Legal certification of the draft report is also required.

Action Required: The transmittal of the draft report will include technical certification by the responsible functional chief, as well as legal certification.

12. Editorial / Report Inconsistencies. Generally, the document would benefit from a comprehensive in-house review for editorial content and consistency.

1. Tables 23, 24, and 25 of the main report list inconsistent total equivalent annual costs for the various alternatives.

3. The selected plan is not described consistently in the main report and appendixes. The draft feasibility report should contain comprehensive and consistent descriptions of the selected plan in the main report and supporting appendixes.
4. The main report does not distinguish between costs allocated to mitigation and costs allocated to ecosystem restoration. These costs should be segregated and clearly shown in the draft report.

District Response: Concur. Changes shall be made in the report where appropriate.

Action Required: The district will make the editorial changes that were identified in the HQUSACE comments, in the draft report.

13. Release of the Draft Report: Release of the draft report to the public is not approved at this time, considering the requirement for additional coordination and potential reformulation of alternatives required to respond to comments 6.a. and 7, and uncertainty in the proposed plan to be recommended.

Action Required: The district will meet with the U.S. Fish and Wildlife Service (USFWS), the local sponsor and Riverside County to reformulate plans that include activities by both Federal agencies. The results of this formulation will be presented in the draft report in the same level of detail as the other alternatives that are presently described in the AFB documentation. Since the district expects to revise the proposed recommendation to address resource agencies concerns and non-Federal Sponsor’s desires, the District will submit the recommendations section of the draft report to HQUSACE (ATTN: CECW-PE) for approval in advance of the release of the draft report to the public. Along with the recommendation section, the district will also provide summary supplemental information clearly describing the new proposed plan, its costs and benefits, the division of responsibilities for implementation and an indication of the views of the USFWS. A conference call between the District, Division and HQUSACE will be scheduled to discuss the new proposed plan and to expedite release of the draft report.