Project DescriptionSeveral parameters that would govern the Program implementation have been identified. The OOD lands would be subject to different water availability than the in-district lands. OOD lands shall only receive water under OID’s pre-1914 water right. OID would use DWR snowfall and runoff forecasting, Tri-dam project snow surveys and real-time hydrology information throughout the irrigation season on the Stanislaus River from the Department of Water Resources California Data Exchange Center. During the irrigation season OID would continuously monitor DWR’s reported full natural flow at Goodwin Dam to determine the amount of pre-1914 water that was available and then ensure surface water diversions for these OOD lands did not exceed that. The amount of available pre-1914 surface water will change from month-to-month and year-to-year based on such a calculation. Additionally, the capacity of OID’s existing conveyance system is limited when there is peak in-district demand, usually July to mid-August. Since in-District lands’ ability to receive water would not be impacted by OOD deliveries there may be times when pre-1914 surface water is available but cannot be delivered due to capacity limitations within OID’s system. During the peak of the irrigation season (generally July-August), OOD landowners can anticipate windows of time where the OID system has reached full capacity from in-district demand and water cannot be delivered to their OOD lands. OID would make as much surface water available as possible within the constraints listed above, without impacting in-district constituents. OID estimates that up to 25,000 acre-feet of water could be conveyed through the system to OOD lands throughout the irrigation season.
An analysis of New Melones Reservoir hydrology with the effects of the Project’s proposed water transfer was conducted and is attached in the Hydrology Transfer Memo located in Appendix B at the end of the Initial Study/Mitigated Negative Declaration (IS/MND). The analysis consists of a baseline operation in which there is no water transferred, and a proposed action operation in which 25,000 acre-feet is transferred in all water year types except critically dry. While the baseline conditions for the IS/MND do include some transferred water (OID has been delivering some OOD water since the mid-1990s), the baseline operation in the Hydrology Transfer Memo consisted of no transferred water for simplicity.
Compared to the analysis baseline, results of the operation comparison primarily show a lessening of reservoir storage in New Melones Reservoir in any year the transfer occurs, and during sequential years this annual depletion can accumulate. The exception to this result occurs in wetter years when the reservoir fills and inflow exceeds downstream demand releases and additional reservoir releases are needed to reach flood control reservoir storage reservation objectives.
Minimum release requirements below Goodwin Dam are always met in both Model scenarios. Due to the additional depletion of reservoir storage in the transfer operation and the subsequent accumulation of less reservoir storage, less release in excess of minimum release requirements will occasionally occur. This outcome will occur during times when reservoir flood control reservation objectives are initially approached in a year or when reservoir management releases occur during the summer. The results of the analysis demonstrate that the proposed Project will not have a significant effect on the storage capacity of New Melones, nor will it cause the cold-water pool to be reached more often than without the Project.
Existing OID policies will remain in effect during the Program term. OID’s Fringe Parcels Policy (Policy) applies to those parcels that are partially within the District boundaries and have a total irrigated acreage in excess of that total acreage which lies within the OID boundaries. In accordance with the Policy, these fringe parcels are provided an allocation of water determined by crop type for their in-district acreage at in-district rates. Once they have exceeded that allocation, they are billed at the OOD volumetric rate. OOD water can be requested for these fringe parcels if and when it’s needed during years when OOD water is determined to be available. These fringe parcels are not required to participate in the 10-year Program to remain eligible to receive OOD water from OID. Additionally, the United States Army Corps of Engineers (USACE) owns and operates the Orange Blossom Park along the Stanislaus River. Through an agreement with OID, the USACE has received OOD water for irrigation of the park. The park is also not required to participate in the 10-year Program to remain eligible to receive OOD water from OID. OOD water deliveries to fringe parcels, as well as to Orange Blossom Park, are accounted for within the 25,000 acre-feet of OOD water anticipated to be conveyed and delivered to OOD lands. Varying levels of construction by the participating landowners are anticipated to be needed in order for these OOD lands to receive OID surplus water. Some landowners have existing canal delivery points (turnouts) and pipelines in place; others are adjacent to an OID canal but require a turnout and short length of new pipeline to be installed; other landowners are not adjacent to OID canals and would require a new turnout and a considerable length of new pipeline to be installed, whether through developed agricultural ground or native ground. The Program also proposes two private reservoirs on private landowner property: one would be up to four acres; and the other would be up to 15 acres (see Figure 2-2 of the IS/MND). These reservoirs are located adjacent to, but not within, parcels that are participating in the Program. While the IS/MND is not intended to include a detailed assessment of each individual private construction project on the lands participating in the Program; the participating parcels would be included in the overall Program footprint and the IS/MND would provide all known anticipated potential impacts based on the parcel location, general construction information and known species of concern in the Program vicinity. A list of suitable mitigation measures based on all known potential impacts within the project footprint would be included in the IS/MND. Landowners of the participating parcels that need new infrastructure would be required to provide an independent biological field study performed by a qualified biologist to evaluate their specific Program area before any construction occurs. All applicable mitigation measures identified in the IS/MND will be followed during construction activities. Should any mitigation measures not identified in the IS/MND be required by the qualified biologist as a result of a site-specific field survey, then a subsequent CEQA review for that specific site would be required. All recommended mitigation measures must be met during construction activities. OID, as lead agency, maintains the right to supervise mitigation and monitoring activities during private construction activities.