ENVIRONMENTAL CONSEQUENCES. The Vallecito Reservoir fishery can be affected by variations in the amount of water in the reservoir and associated changes in water quality, available habitat, and productivity. To a greater extent, the Pine River fishery can be affected by flow levels. The Contract would allow for the use of up to 3,000 af of irrigation water for miscellaneous uses. Current use of this water for irrigation results in an estimated depletion to the San ▇▇▇▇ Basin of 1,140 af (38 percent depletion rate for irrigation water) annually. Once fully used for M&I purposes, the depletion is estimated at 595 af7. While it is contemplated that a reduced depletion would occur if water was converted from irrigation to M&I uses, this assessment assumes that the historic depletion of 1,140 af would continue because the Contract simply allows for the use but does not implement it. There is no guarantee that any water would be used for miscellaneous uses. Changes under the Contract represent an insignificant amount of change in Pine River flows (see Table 4), water distribution in the service area, and reservoir operations. For example, annual Pine River flows immediately downstream from Vallecito Reservoir varied from 116,400 af in 2002 to over 416,000 af in 1987 and therefore changing the use of 3,000 af of this water is relatively minor. In the long term, summer releases from Vallecito could increase by 10 cfs while winter flows could be reduced by an average of 16 cfs in November and 9 cfs in December to “restore” the water released under the Contract. January through May releases would be reduced by 1 to 4 cfs, and January and February would continue to have the lowest flows of the year. Winter flow levels will continue to periodically fall below recommended levels; however, historic minimum flows (pre-2002) would not have to be reduced as a result of the Contract. Reservoir levels would be slightly lower in the late summer and fall but should not have significant effects on reservoir productivity. Overall, implementation of the Proposed Alternative is not projected to significantly change Vallecito Reservoir operations or Pine River flows; therefore, there should be no impacts expected to the respective fisheries under the Proposed Alternative. Under the No Action Alternative, significant changes in the fisheries are not projected, although if development of new water sources occurred this could affect fisheries and river depletions, depending on which sources are developed.
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ENVIRONMENTAL CONSEQUENCES. The Vallecito Reservoir fishery can Overall, reservoir operations and streamflows should not be affected by variations in significantly different under the amount of water in No Action and Proposed Alternatives. Under the reservoir and associated changes in water qualityProposed Alternative, available habitat, and productivity. To a greater extent, the Pine River fishery can be affected by flow levels. The Contract would allow for the use of up to it is anticipated that 3,000 af of irrigation water for miscellaneous uses. Current use would gradually (over a period of this water for irrigation results in an estimated depletion to the San ▇▇▇▇ Basin of 1,140 af (38 percent depletion rate for irrigation watermany years) annually. Once fully used for M&I purposes, the depletion is estimated at 595 af7. While it is contemplated that a reduced depletion would occur if water was converted from irrigation to M&I uses, this assessment assumes that the historic depletion of 1,140 af would continue because the Contract simply allows for the use but does not implement it. There is no guarantee that any water would be used for miscellaneous uses. Changes Hydrological impacts are determined by overlaying the Proposed Alternative onto historical reservoir operations and ditch diversions (i.e., water demands) to determine impacts. Three primary assumptions were used in the hydrology analysis: • The entire 3,000 af would be required to be released for M&I purposes each year; • The entire 3,000 af would be required to be “restored” each year prior to the beginning of the next year’s irrigation season; • The 3,000 af would be released only during a call on the river (i.e., during portions of the irrigation season); similar to how the 400 af is currently released; and • The 3,000 af would not come from the Southern Ute Indian Tribe's 1/6 allotment of Project water. It should be noted that the assumption of fully using the 3,000 af each year is a maximum case; releases would actually vary from zero to 3,000 af depending on water conditions each year. Based on these assumptions, an operation study was developed and is shown in Appendix F.6 The water used for miscellaneous uses would be released to the Pine River generally during the period of the irrigation season if there was a call on the river. This would be over a period ranging from an estimated 48 days to 141 days, depending on river flow conditions. When the additional 3,000 af is fully developed, the M&I daily water releases could vary between approximately 10.7 and 31.5 cfs during the irrigation season, once again depending on river flow conditions. These releases would increase streamflows slightly in the water critical area (from the dam to the Pine River Canal diversion located approximately 4 miles downstream from Bayfield). Below this point, irrigation season streamflows should not change. Vallecito Reservoir content at the end of the irrigation season under the Proposed Alternative could be up to 3,000 af less than under the No Action alternative. This would normally represent a 1 to 2-foot reduction in reservoir depth in the fall but up to 4 feet in extremely dry years such as 1977. As stated above, this analysis assumes that any reduction in storage as a result of M&I releases would need to be “restored” each year. The approach for restoring this water is to keep in storage (i.e., not release) those historical reservoir releases that were not needed to meet the needs of project users. To determine if the release of the water for miscellaneous uses in any given year would impact the irrigation supply for that year, the reservoir content at the end of the irrigation season under the Proposed Alternative scenario was compared to the historical content. To determine if "restoring" the water released under the Proposed Alternative would impact the following year's water supply, the reservoir content at the beginning of the next irrigation season under the Proposed Alternative scenario was compared to the historical content at the beginning of the next irrigation season. In both of these comparisons, the Southern Ute Indian Tribe's 1/6 portion of storage water available to it during the given water year was identified and set aside. Only the District’s 5/6 portion was used to meet the miscellaneous water needs. In this analysis, the irrigation season is defined as May 11 through November 15 of each year and the winter season is defined as November 16 through May 10. Impacts to the Pine River were determined by analyzing releases modeled for the Proposed Alternative and comparing those to the historical releases. For the purposes of 6 The Operation Study simulated the release (and subsequent restoration) of the M&I Contract represent an insignificant amount water throughout the entire historic operation of the Project (1941-2006) to determine impacts to historical supplies and releases. In effect, the Operation Study simulates operating the reservoir in a more efficient manner, similar to the past 10 years of operation. the analysis, releases in excess of the needs of project users are defined as historical releases greater than 700 cfs during the irrigation season and greater than 25 cfs during the non-irrigation season; as indicated previously, this is based on observations made over many years of reservoir operations and irrigation diversions. In many cases, these releases were made in anticipation of high spring runoff inflow or to reach a storage content of less than 77,000 af in the winter to avoid damage to the radial gates caused by ice buildup. In most years, these releases in the fall are substantial in order to reach the winter storage target of 77,000 af. While some of these releases will continue to be necessary even under the Proposed Alternative (i.e., reservoir storage levels will need to be reduced in anticipation of high runoff and to meet winter storage limits), the release volumes could be reduced at times by the amounts necessary to “restore” water that has been or will be released for M&I purposes. For this analysis, the daily reduction was calculated so that the historical releases would never be reduced when they were below 25 cfs during winter months or 700 cfs during the irrigation season. If the historical daily releases were less than 25 cfs in the winter or 700 cfs during the irrigation season, then no changes were made to releases that day. Table 4 summarizes changes (as compared to historical operations) in reservoir releases if managing the potential excess releases were used to “restore” the reservoir under the Proposed Alternative. Table 4 also shows that releases would be slightly increased during the months of July-October and slightly reduced during the months of November - April. A majority of reductions in historic winter releases would occur in November, the first recovery month after the irrigation season Table 4. Change in Historical Vallecito Reservoir releases under the Proposed Alternative. Month Percentage change in mean release Change in mean release (cfs) Change in minimum release (cfs) Change in maximum release (cfs) January -7% -4 0 0 February -5% -3 0 0 March -4% -4 0 0 April -1% -2 0 0 July 1% 8 11 0 August 2% 10 11 0 September 2% 10 5 0 October 3% 9 2 13 November -15% -16 0 -20 December -11% -9 0 0 Evaluation of reservoir content required a slightly different analysis than that used in predicting streamflow below the reservoir. It was assumed that any additional water stored in Vallecito Reservoir as a result of more efficient operations, and which better conserved storage and controlled releases to those needed to meet Project purposes, would not only benefit the District, but also the Southern Ute Indian Tribe. This was accomplished by modeling the operation of the reservoir to account for additional demand of 3,600 af/yr (3,000 af or 5/6 for the District and 600 af or 1/6 for the Tribe). Any additional water allotted to the Tribe as a result of more efficient operations would not be included in the M&I Contract water; however, for simplification purposes, it was assumed in this analysis that any additional allocation to the Tribe would be released each year (to avoid changing the historical reservoir content). Superimposing the release of 3,600 af/yr on the historical reservoir operation demonstrated that historical water supplies of the District and the Tribe were never impacted by the release of the water for miscellaneous needs. This was accomplished by comparing the historical November 15 content to the modeled content. The analysis also showed that by May 10, the reservoir had returned to the historical content 63 out of 65 years. In the two years that the reservoir didn't return to the historical content by May 10, it was restored by mid-June, before the date of maximum content and before releases from storage were required for irrigation deliveries. Based on this analysis, there appear to be no significant impacts to hydrological resources or reservoir operations as a result of implementing the Proposed Alternative. Moreover, the impacts to hydrological resources identified in this analysis would likely be less than those described in this section when considering the following: - The impact analysis does not take into account that approximately 400 af of the 3,000 af is already being used for M&I purposes. - The impact analysis does not take into account the mitigating effects of return flows on the system. As mentioned above, between 50 and 90 percent of the M&I uses would be returned to the river which would reduce the impacts to river flows. - As mentioned above, the assumption in the analysis that the full 3,000 af of M&I water would be released each year could be high; releases would actually vary from zero to 3,000 depending on hydrologic conditions. - The analysis assumes the leased water would be released only during the irrigation season. If a new Third Party Contractor called for a year-round diversion, this could result in small increases in winter flows and small decreases in irrigation season flows (as compared to those shown in Table 4) in the reach of river upstream from the Pine River flows (see Table 4)Canal diversion. - The analysis does not take into account that irrigated acreage within the District has been and continues to be reduced due to development such as homes, commercial buildings, farm buildings, roads, gas ▇▇▇▇▇, and expansion of the Town of Bayfield. The reduction of the irrigated lands from 1945 to 2005 is roughly estimated to be 1,300 acres which represents approximately 2,700 af of storage water distribution that could be used for M&I purposes. It should also be noted that this analysis does not take into account impacts to historical reservoir storage if the Tribe had used all of its allotted storage each year. If and when this happens in the service areafuture, it could affect (in some years) the maximum reservoir content of a given year which would impact both the Southern Ute Indian Tribe's and reservoir operationsDistrict’s water supply the following year – independent of the Proposed Alternative. For exampleThis analysis was developed to show only that historical supplies (including the Tribe's) and hydrological resources would not have been impacted by the Proposed Alternative. The analysis does show that the releases for the M&I Contract water would not be derived from the Tribe’s allocation of Project water; therefore, annual Pine River flows immediately downstream from Vallecito Reservoir varied from 116,400 af in 2002 to over 416,000 af in 1987 and therefore changing the Tribe’s full allocation of water would be available for Tribal use each year. This EA evaluates the use of 3,000 af of this Project water for miscellaneous uses. As identified in the Contract, it is relatively minorpossible that in the future, additional water may be used for miscellaneous uses resulting in cumulative effects on hydrologic resources. In If additional water were used for miscellaneous uses, some would likely be for larger Third Party contracts for use outside of the long termProject service area, summer releases in which case water would come from Vallecito could increase the Voluntary Shareholder Pool previously discussed. Potential impacts to hydrologic resources, including irrigation water supplies, would be determined by 10 cfs while winter flows could separate NEPA evaluations to be reduced by an average completed prior to approval of 16 cfs in November and 9 cfs in December to “restore” any Third Party Contract where the water released under was being delivered outside of the ContractProject service area. January through May releases This analysis would include the cumulative effect of delivering the additional water on top of the 3,000 af being analyzed in this NEPA document. From a hydrologic standpoint, the impacts of using water from the Voluntary Shareholder Pool are not anticipated to be significant. The water would be reduced derived by 1 to 4 cfsshortening the irrigation season or decreasing the supply of only those irrigators who voluntarily gave up their water. Because the water would be made up directly from irrigation supplies from those who volunteered, and January and February would continue to have the lowest flows of the year. Winter flow levels will continue to periodically fall below recommended levels; however, historic minimum flows (pre-2002) water would not have to be reduced “restored” as in the previous analysis. Prior to providing water to the Pool, the individual shareholders would be required by the District to prove that doing so would not impact other shareholders’ abilities to receive their water. The amount of water that would be removed from the Pine River Basin as a result of the Contract. Reservoir levels this future action would be slightly lower insignificant when compared to the total amount of water in the late summer and fall but should not have significant effects on reservoir productivitybasin. Overall, implementation In the event that a portion of the Proposed Alternative is additional 3,700 af of water that could possibly be used for miscellaneous uses were not projected to come from the Voluntary Shareholder Pool (i.e., if the water were leased within the District service area), the impacts of that action would be overlaid on top of the existing operations at that time, which would include the action being covered in this EA (the use of 3,000 af of Project water for miscellaneous uses). In such a case, and prior to approving each use of this water, the action would be analyzed to determine if this additional water could be restored without impacting the irrigation supplies. The operation study developed for this analysis simulates an operational method which has generally been implemented by the District using historical hydrology that minimizes or avoids impacts to supply. Future operation of the reservoir will be dependent on hydrology, snowpack, runoff characteristics, summertime precipitation, and other factors. As such, nothing in this document or the Contract requires the District to operate the reservoir in exact accordance with the operation study simulation to supply the M&I Contract Leased Water. However, if reservoir operation strategies implemented by the District result in impacts significantly change Vallecito Reservoir operations or Pine River flows; thereforedifferent than addressed in this EA, there should additional operating plan reviews, involving the District, Southern Ute Indian Tribe, and Reclamation, would be no impacts expected to the respective fisheries under the Proposed Alternativerequired. Under the No Action Alternative, significant changes in to the fisheries hydrology or water quality are not projected, although if development of new water sources occurred this could affect fisheries and river depletions, depending on which sources are developedexpected.
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