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HomeMy WebLinkAbout12.13.19 Email from FERC - Docket P-619-167 PGE Bucks Creek-Grizzly Project RE Requests for Minimum Instream Flow and Lake Level Variance From:Lose, Sarah@Wildlife To:Visinoni, Jamie; Lind, Amy -FS; Edlund, Leslie - FS; Lawson, Beth@Wildlife; Aondrea_Bartoo@fws.gov Cc:Joseph, Matthew Subject:RE: Updated Review/Approval Request - Bucks Creek Project, FERC No. 619 - Flow and Lake Elevation Variance Date:Wednesday, October 16, 2019 1:36:39 PM Attachments:LowerBucksVarianceRequest_CP_10-16-19.docx *****CAUTION: This email was sent from an EXTERNAL source. Think before clicking links or opening attachments.***** Hi Jamie- We have made some edits to the proposed variance request. Please see the edits on the attached document. With the acceptance of these edits, CDFW approves this variance request. Thank you! Sarah C. Lose Senior Environmental Scientist (Specialist) CA. Dept of Fish and Wildlife/North Central Region Water Program-FERC Coordinator 1701 Nimbus Rd. Rancho Cordova, CA. 95670 (916) 747-5226: cell From: Visinoni, Jamie <JNVS@pge.com> Sent: Monday, August 26, 2019 12:18 PM To: Lind, Amy -FS <amy.lind@usda.gov>; Edlund, Leslie - FS <leslie.edlund@usda.gov>; Lawson, Beth@Wildlife <Beth.Lawson@wildlife.ca.gov>; Lose, Sarah@Wildlife <Sarah.Lose@wildlife.ca.gov>; Aondrea_Bartoo@fws.gov Cc: Joseph, Matthew <MWJA@pge.com> Subject: Updated Review/Approval Request - Bucks Creek Project, FERC No. 619 - Flow and Lake Elevation Variance Importance: High Hello All, Thank you for sharing your questions and concerns regarding the Bucks Creek variance request when we met last week. We have provided more detail on the water management approach in our variance request, please see the updated request below: Pacific Gas and Electric Company (PG&E) plans to perform extensive repairs and maintenance in 2020 at Lower Bucks Lake Dam and Grizzly Forebay Dam, part of PG&E’s Bucks Creek Hydroelectric Project, Federal Energy Regulatory Commission (FERC) Project No. 619. PG&E is requesting U.S. Forest Service (Forest Service), California Department of Fish and Wildlife (CDFW), and the U.S. Fish and Wildlife Department review and approval to temporarily reduce the minimum instream flows (MIF) and minimum lake elevation to levels below those required under Article 13 for Bucks Creek and Grizzly Creek. The request for flow reduction may not be needed but is being submitted as a precautionary measure to ensure construction crews safe access to the perform work on and around the dams. Scope of Construction and Schedule Lower Bucks Dam Work – In a letter dated December 17, 2014, FERC requested that PG&E address several follow-up action items from the 2014 Dam Safety Inspection for the Project. The letter stated that “Severe spalling and surface delamination of concrete has occurred on the downstream abutments and downstream face of the \[Lower Bucks\] dam. The condition should be carefully evaluated, and a repair plan developed.” PG&E performed a condition assessment in 2016 and 2017 which resulted in the installation of a geomembrane liner as one of the recommended repairs. Engineering is underway to address the downstream lining per the 2014 direction. The proposed project includes installation of a geomembrane liner on the upstream face of the dam to reduce seepage and protect the dam from further freeze-thaw damage. To install the liner, Lower Bucks Lake will be completely dewatered, and sediment will be excavated adjacent to the dam to support the geomembrane placement access. The initial drawdown of Lower Bucks Lake will be conducted using a combination of pumping, drafting water through the Grizzly Intake, and exercising the Lower Bucks Dam low level outlet (LLO) until reservoir elevation falls below the minimum operating elevation of the Grizzly Intake. The remaining pool of water in the reservoir will be dewatered using a combination of the LLO and/or pumps. The drawdown and dewatering of Lower Bucks Lake, sediment removal, and geomembrane installation effort will be coordinated with a multi-unit outage scheduled for May to November 2020. During the dewatered period, instream flows downstream of Lower Bucks Dam into Bucks Creek will be satisfied by either: 1) the Milk Ranch Conduit (MRC), which usually flows directly into Lower Bucks Lake but may be re-routed downstream of Lower Bucks Dam, or 2) a bypass gravity flow system from Bucks (Storage) Lake LLO that will be routed downstream of Lower Bucks Dam. The ideal phasing would be to start with MRC into Bucks Creek utilizing flows from the various diversions; once those flows begin to recede and approach the Bucks Creek required MIF, the system will be switched over to the Bucks Storage LLO gravity system; then finally towards the end of the work, based on a calculation of storage volume in Three Lakes, the system would by switched back to MRC for the remainder of the work. This approach provides a redundancy in the system for the duration of work. Grizzly Forebay/Dam Work – Logs and woody debris build up at the Grizzly Forebay overpour spillway during the wet season. Some of these have become waterlogged and have sunk, accumulating upstream of the dam. This project proposes to wet dredge woody debris and accumulated sediment from the reservoir adjacent to the LLO and the Bucks Powerhouse intake structure. This accumulated material impacts both the intake and LLO. The sediment drawn into the intake is causing deterioration to the Bucks Powerhouse runners creating increased maintenance. Debris build up may also be drawn into the LLO which could affect its reliability to provide required instream flow releases downstream of the structure. PG&E has identified May to November 2020 as the potential outage window for the dual Bucks/Grizzly Powerhouses to support this work. License Requirement License Article 13 requires, in part, that PG&E maintain a minimum instream flow in Bucks Creek below the Lower Bucks Dam and from Grizzly Forebay to Grizzly Creek. Minimum streamflows are: (1) Minimum streamflows from Lower Bucks Lake to Bucks Creek: Period Flow, in cubic feet per second (cfs) November 1 through April 30 4 cfs May 1 through June 30* 8 cfs July 1 through October 31 6 cfs (2) Minimum streamflows from Grizzly Forebay to Grizzly Creek: Flow, in cubic feet Period per second (cfs) November 1 through April 30 4 cfs May 1 through June 30* 8 cfs July 1 through October 316 cfs License Article 13 also requires PG&E maintain a minimum water elevation for all lakes. The minimum elevation for Lower Bucks Lake is 4,966 feet. Schedule for Temporary Flow and Reservoir Elevation Variances Bucks Creek Variance To ensure safe and efficient constructability, cost, and schedule, PG&E is seeking a stst temporary flow variance of 6 cfs from June 1 through July 1. A flow of 6 cfs will be achieved through the bypass piping system from Bucks Lake to Bucks Creek and may be augmented with water from the Milk Ranch Conduit (MRC), if available. If enough water is available through the MRC, PG&E expects to be able to achieve the License required MIF of 8 cfs. In addition to the flow variance, PG&E requests the 24-hour average of the flow (mean daily flow) be used for minimum stream flow measurement and reporting for May 1 through November 1, 2020. PG&E will average all the instantaneous readings from midnight of one day to 11:59 pm of the next day. Flow monitoring will be achieved by installing a temporary flow meter on the bypass piping system. Grizzly Creek Variance To support the debris and sediment removal work, a pump system will be deployed to maintain a consistent lake elevation. PG&E is seeking a variance from July 1 through November 1, 2020 to allow flow releases below Grizzly Dam to match the natural inflow into the reservoir, which may drop below the license required 6 cfs depending on water year. In addition to the flow variance, PG&E requests the 24-hour average of the flow (mean daily flow) be used for minimum instream flow measurement and reporting for July 1 through November 1, 2020. PG&E will average all the instantaneous readings from midnight of one day to 11:59 pm of the next day. Flows will be monitored and recorded at NF22. Adjustments to pumping will be made daily to maintain the reservoir elevation, whereby generally matching inflow to outflow. Lower Bucks Lake Water Elevation Variance PG&E requests a variance to the minimum elevation for Lower Bucks Lake, the lake will be completely dewatered for the majority of the outage between May 1 to November 1 of 2020. Biological Resource Evaluation Bucks Creek Minimum Instream Flow Variance In the event of a very dry year that results in June flows of less than 2 cfs in the MRC, flow in Lower Bucks Creek could drop below the MIF of 8 cfs, to as low as 6 cfs. Based on surveys conducted during relicensing (PG&E 2018), Lower Bucks Creek is inhabited by rainbow and brown trout, with brown trout being dominant at the upstream end of the creek, and rainbow trout being dominant further downstream. There are no special status aquatic species known from this stream. All lifestages of rainbow trout (adult, juvenile, fry and spawning) are likely to be present in June, although spawning may be complete by that time, and alI lifestages of brown trout, except spawning would be present. An instream flow study was prepared for Lower Bucks Creek (Thomas R. Payne and Associates 1991. Instream Flow Study for Milk Ranch, Bucks, and Grizzly Creeks. Bucks Creek Project (FERC 619). Prepared for PG&E). Based on this study, a flow reduction from 8 cfs to 6 cfs would result in a reduction in habitat for rainbow trout of 11 % for fry, 15% for juveniles, and 6% for adults. Spawning habitat would be reduced by 45%, if spawning has not completed by that time. Habitat reductions for brown trout would generally be less, ranging from 3% for juveniles to 7% for adults. For all lifestages except rainbow trout spawning, the habitat reduction would be minor and would adjust the timing of the License required MIF reduction from 8 to 6 cfs forward by up to 4 weeks. This would have minimal to no effect on the abundance or health of these fisheries. For rainbow trout spawning, the effect might be more pronounced if redds were still active at the time of the flow reduction, and if redds were placed relatively high in the channel. Flow Averaging Period Variance The impact of moving from an instantaneous MIF requirement to a 24-hour MIF requirement is likely negligible. This variance would allow flows to drop below 6 cfs during a brief period (a couple of hours during any given day) during May through October 2020, without requiring a variance report for each such occurrence. Trout would not be affected by such short-term variations in flow. Lower Bucks Lake Minimum Pool Variance As described above, Lower Bucks Lake will be completely dewatered. PG&E is working with the California Department of Fish and Wildlife (CDFW) to develop a plan for conducting a fish rescue and to develop a restocking plan. To the extent a fish rescue may safely be implemented, PG&E does not expect the fish rescue to provide a biological/environmental benefit. Fish that are rescued will likely be moved to Bucks Lake (Storage), where they would be available to anglers, but will not appreciably increase fish populations (or angler catch-per-unit-effort) in Bucks Lake given the much smaller size of Lower Bucks Lake and the proportion of fish the crews will likely be able to safely rescue. All fish that are not rescued are expected to perish. PG&E and CDFW are also working together to develop a restocking plan for Lower Bucks Lake that will be implemented after the lake refills. This plan will be focused on restocking rainbow trout over a range of sizes. Bucks Lake supports the same species of fish as Lower Bucks Lake. Other fish species will gradually recolonize Lower Bucks Lake, but relicensing studies found that entrainment rates are low in Bucks Lake, and therefore, this is expected to take several years. Lower Bucks Lake and the portion of Bucks Creek immediately downstream of Lower Bucks Dam are within designated critical habitat for Sierra Nevada yellow-legged frog SNYLF), listed as endangered under the Endangered Species Act. Surveys during relicensing did not identify any occurrences of this species in either of these areas. The nearest SNYLF observation was in Bear Ravine located in a drainage about 0.3 miles north of Lower Bucks Dam. The flow and water level variances associated with this project would not adversely affect habitat values for this species. A separate biological assessment is being prepared for submission to the U.S. Fish and Wildlife Service regarding the potential impacts of this project on SNYLF and its habitat, but no impacts are anticipated. Grizzly Creek Flow Variance Grizzly Creek has the same fish assemblage as Bucks Creek, rainbow trout and brown trout, with no special status aquatic species. As with Bucks Creek, brown trout dominate the fish community closer to the dam, while rainbow trout are dominant at the more downstream end of the reach. Grizzly Creek receives flow from Lower Bucks Lake when the Grizzly Powerhouse is in operation, but both the Grizzly powerhouse and the tunnel will be offline, and so flow from Lower Bucks Lake will not be available to supplement natural inflow. A flow reduction below the current MIF of 8 cfs in May and June is unlikely to occur based on either the unimpaired flow analysis done as part of relicensing or a review of hydrology since 2000. Flow reductions below the current MIF of 6 cfs from July 1 through October 31 are more likely to occur, with naturally occurring inflows having dropped below 6 cfs during the summer months in 10 of 19 years between 2000 and 2018, with flows dropping to less than 2 cfs for some months in three of those years. However, those years had varied water year types, one each in above normal, below normal and critical, and other years with the same water types had higher flows. Therefore, it is not possible to predict what naturally occurring inflow might be in any given year. PG&E is proposing to release the full natural inflow of Grizzly Creek below Grizzly Forebay (i.e., inflow equals outflow), so fish would experience the same natural conditions they would if the project were not present. However, during normal project operation, the natural flow regime below Grizzly Forebay is supplemented under some conditions by water diverted from Lower Bucks Lake. This ability to supplement flows would not be available with the proposed work, as both the Grizzly Powerhouse and tunnel would be offline for maintenance and repairs and the source flows from Lower Bucks will be unavailable during the Lower Bucks Lake dewatering. The impacts of flow reductions to less than 6 cfs would depend on the water year type and the magnitude and duration of the variance. For short-term variations of minor magnitude, that would be experienced under normal or wetter water years, fish would move into deeper habitat to adapt to the flow change, and few impacts would be anticipated. Under longer-term variations of greater magnitude, as would be experienced under dry water years, the impacts would increase. Instream flow models for Grizzly Creek (TRPA 1991) indicate that flows of 2 cfs provide 8 to 12% less habitat for brown trout lifestages (fry, juvenile and adult) than flows of 6 cfs based on 50% exceedance condition accretion flows downstream of the dam in September (selected as a worst-case month). For rainbow trout, this flow reduction would reduce habitat by 14 to 29%. This reduction in habitat would crowd fish into a smaller area but is unlikely to result in large scale fish mortality. If flows were reduced to zero cfs, habitat for brown trout would be reduced by 17 to 23% and for rainbow trout by 26 to 56%. This might result in more mortality for rainbow trout, but the populations of both species would persist. Flow Averaging Period Variance The impact of moving from an instantaneous MIF requirement to a 24-hour MIF requirement is likely negligible. This variance would account for lags between reservoir elevation monitoring and adjustment of pumping rates to match outflow to inflow during May through October 2020, without requiring a variance report for each such occurrence. Trout would not be affected by such short-term variations in flow. PG&E requests your review and concurrence as soon as possible. Thank you for your timely attention to this matter. All concurrence emails and/or letters we receive will be included in our filing with FERC. PG&E staff is available to discuss this variance request in more detail, if needed. If you have any questions, please call: General Questions – Jamie Visinoni, 530-215-6676 Project/Engineering – Jeff Jukkola, 530-624-8640 Biological Review – Larry Wise, 925-415-6353 Thank you, Jamie Visinoni Hydro License Coordinator | Power Generation Pacific Gas and Electric Company d: N/A | m: (530) 215-6676 | e: jamie.visinoni@pge.com Pacific Gas and Electric Company (PG&E) plans to perform extensive repairs and maintenance in 2020 at Lower Bucks Lake Dam and Grizzly Forebay Dam, part of PG&E’s Bucks Creek Hydroelectric Project, Federal Energy Regulatory Commission (FERC) Project No. 619. PG&E is requesting U.S. Forest Service (Forest Service), California Department of Fish and Wildlife (CDFW), and the U.S. Fish and Wildlife review and approval to temporarily reduce the minimum instream flows (MIF) and minimum lake elevation to levels below those required under Article 13 for Bucks Creek and Grizzly Creek. The request for flow reduction may not be needed but is being submitted as a precautionary measure to ensure construction crews safe access to the perform work on and around the dams. Scope of Construction and Schedule Lower Bucks Dam Work – In a letter dated December 17, 2014, FERC requested that PG&E address several follow-up action items from the 2014 Dam Safety Inspection for the Project. The letter stated that “Severe spalling and surface delamination of concrete has occurred on the downstream abutments and downstream face of the \[Lower Bucks\] dam. The condition should be carefully evaluated, and a repair plan developed.” PG&E performed a condition assessment in 2016 and 2017 which resulted in the installation of a geomembrane liner as one of the recommended repairs. Engineering is underway to address the downstream lining per the 2014 direction. The proposed project includes installation of a geomembrane liner on the upstream face of the dam to reduce seepage and protect the dam from further freeze-thaw damage. To install the liner, Lower Bucks Lake will be completely dewatered, and sediment will be excavated adjacent to the dam to support the geomembrane installation. The initial drawdown of Lower Bucks Lake will be conducted using a combination of pumping, drafting water through the Grizzly Intake, and exercising the Lower Bucks Dam low level outlet (LLO) until reservoir elevation falls below the minimum operating elevation of the Grizzly Intake. The remaining pool of water in the reservoir will be dewatered using a combination of the LLO and/or pumps. The drawdown and dewatering of Lower Bucks Lake, sediment removal, and geomembrane installation effort will be coordinated with a multi-unit outage scheduled for May to November 2020. During the dewatered period, instream flows downstream of Lower Bucks Dam into Bucks Creek will be satisfied by either: 1) the Milk Ranch Conduit (MRC), which usually flows directly into Lower Bucks Lake but may be re-routed downstream of Lower Bucks Dam, or 2) a bypass gravity flow system from Bucks (Storage) Lake LLO that will be routed downstream of Lower Bucks Dam. The ideal phasing would be to start with MRC into Bucks Creek utilizing flows from the various diversions; once those flows begin to recede and approach the Bucks Creek required MIF, the system will be switched over to the Bucks Storage LLO gravity system; then finally towards the end of the work, based on a calculation of storage volume in Three Lakes, the system would by switched back to MRC for the remainder of the work. This approach provides a redundancy in the system for the duration of work. Grizzly Forebay/Dam Work – Logs and woody debris build up at the Grizzly Forebay overpour spillway during the wet season. Some of these have become waterlogged and have sunk, accumulating upstream of the dam. This project proposes to wet dredge woody debris and accumulated sediment from the reservoir adjacent to the LLO and the Bucks Powerhouse intake structure. This accumulated material impacts both the intake and LLO. The sediment drawn into the intake is causing deterioration to the Bucks Powerhouse runners creating increased maintenance. Debris build up may also be drawn into the LLO which could affect its reliability to provide required instream flow releases downstream of the structure. PG&E has identified May to November 2020 as the potential outage window for the dual Bucks/Grizzly Powerhouses to support this work. License Requirement License Article 13 requires, in part, that PG&E maintain a minimum instream flow in Bucks Creek below the Lower Bucks Dam and from Grizzly Forebay to Grizzly Creek. Minimum streamflows are: (1) Minimum streamflows from Lower Bucks Lake to Bucks Creek: Period Flow, in cubic feet per second (cfs) November 1 through April 304 cfs May 1 through June 30* 8 cfs July 1 through October 31 6 cfs (2) Minimum streamflows from Grizzly Forebay to Grizzly Creek: Period Flow, in cubic feet per second (cfs) November 1 through April 30 4 cfs May 1 through June 30* 8 cfs July 1 through October 31 6 cfs License Article 13 also requires PG&E maintain a minimum water elevation for all lakes. The minimum elevation for Lower Bucks Lake is 4,966 feet. Schedule for Temporary Flow and Reservoir Elevation Variances Bucks Creek Variance To ensure safe and efficient constructability, cost, and schedule, PG&E is seeking a stst temporary flow variance of 6 cfs from June 1through July 1.A flow of 6 cfs will be achieved through the bypass piping system from Bucks Lake to Bucks Creek and may be augmented with water from the Milk Ranch Conduit (MRC), if available. If enough water is available through the MRC, PG&E expects to be able to achieve the License required MIF of 8 cfs. In addition to the flow variance, PG&E requests the 24-hour average of the flow (mean daily flow) be used for minimum stream flow measurement and reporting for May 1 through November 1, 2020. PG&E will average all the instantaneous readings from midnight of one day to 11:59 pm of the next day. Flow monitoring will be achieved by installing a temporary flow meter on the bypass piping system. Grizzly Creek Variance To support the debris and sediment removal work, a pump system will be deployed to maintain a consistent lake elevation. PG&E is seeking a variance from July 1 through November 1, 2020 to allow flow releases below Grizzly Dam to match the natural inflow into the reservoir, which may drop below the license required 6 cfs depending on water year. In addition to the flow variance, PG&E requests the 24-hour average of the flow (mean daily flow) be used for minimum instream flow measurement and reporting for July 1 through November 1, 2020. PG&E will average all the instantaneous readings from midnight of one day to 11:59 pm of the next day. Flows will be monitored and recorded at NF22. Adjustments to pumping will be made daily to maintain the reservoir elevation, whereby generally matching inflow to outflow. Lower Bucks Lake Water Elevation Variance PG&E requests a variance to the minimum elevation for Lower Bucks Lake, the lake will be completely dewatered for the majority of the outage between May 1 to November 1 of 2020. Biological Resource Evaluation Bucks Creek Minimum Instream Flow Variance In the event of a very dry year that results in June flows of less than 2 cfs in the MRC, flow in Lower Bucks Creek could drop below the MIF of 8 cfs, to as low as 6 cfs. Based on surveys conducted during relicensing (PG&E 2018), Lower Bucks Creek is inhabited by rainbow and brown trout, with brown trout being dominant at the upstream end of the creek, and rainbow trout being dominant further downstream. There are no special status aquatic species known from this stream. All lifestages of rainbow trout (adult, juvenile, fry and spawning) are likely to be present in June, although spawning may be complete by that time, and alI lifestages of brown trout, except spawning would be present. An instream flow study was prepared for Lower Bucks Creek (Thomas R. Payne and Associates 1991. Instream Flow Study for Milk Ranch, Bucks, and Grizzly Creeks. Bucks Creek Project (FERC 619). Prepared for PG&E). Based on this study, a flow reduction from 8 cfs to 6 cfs would result in a reduction in habitat for rainbow trout of 11 % for fry, 15% for juveniles, and 6% for adults. Spawning habitat would be reduced by 45%, if spawning has not completed by that time. Habitat reductions for brown trout would generally be less, ranging from 3% for juveniles to 7% for adults. For all lifestages except rainbow trout spawning, the habitat reduction would be minor and would adjust the timing of the License required MIF reduction from 8 to 6 cfs forward by up to 4 weeks. This would have minimal to no effect on the abundance or health of these fisheries. For rainbow trout spawning, the effect might be more pronounced if redds were still active at the time of the flow reduction, and if redds were placed relatively high in the channel. Flow Averaging Period Variance The impact of moving from an instantaneous MIF requirement to a 24-hour MIF requirement is likely negligible. This variance would allow flows to drop below 6 cfs during a brief period (a couple of hours during any given day) during May through October 2020, without requiring a variance report for each such occurrence. Trout would likely not be affected by such short-term variations in flow. Lower Bucks Lake Minimum Pool Variance As described above, Lower Bucks Lake will be completely dewatered. PG&E is working with the California Department of Fish and Wildlife (CDFW) to develop a restocking plan that will be implemented after the lake refills. A fish rescue was not considered a viable option during the lake’s drawdown due to steep terrain, safety concerns and limited access. . This plan will be focused on restocking rainbow trout over a range of sizes including stocking trophy-sized rainbow trout into Lower Bucks Lake to jump-start the fishery for the 2021 fishing and camping season. Bucks Lake supports the same species of fish as Lower Bucks Lake. Other fish species will gradually recolonize Lower Bucks Lake, but relicensing studies found that entrainment rates are low in Bucks Lake, and therefore, this is expected to take several years. Lower Bucks Lake and the portion of Bucks Creek immediately downstream of Lower Bucks Dam are within designated critical habitat for Sierra Nevada yellow-legged frog SNYLF), listed as endangered under the Endangered Species Act. Surveys during relicensing did not identify any occurrences of this species in either of these areas. The nearest SNYLF observation was in Bear Ravine located in a drainage about 0.3 miles north of Lower Bucks Dam. The flow and water level variances associated with this project would not adversely affect habitat values for this species. A separate biological assessment is being prepared for submission to the U.S. Fish and Wildlife Service regarding the potential impacts of this project on SNYLF and its habitat, but no impacts are anticipated. Grizzly Creek Flow Variance Grizzly Creek has the same fish assemblage as Bucks Creek, rainbow trout and brown trout, with no special status aquatic species. As with Bucks Creek, brown trout dominate the fish community closer to the dam, while rainbow trout are dominant at the more downstream end of the reach. Grizzly Creek receives flow from Lower Bucks Lake when the Grizzly Powerhouse is in operation, but both the Grizzly powerhouse and the tunnel will be offline, and so flow from Lower Bucks Lake will not be available to supplement natural inflow. A flow reduction below the current MIF of 8 cfs in May and June is unlikely to occur based on either the unimpaired flow analysis done as part of relicensing or a review of hydrology since 2000. Flow reductions below the current MIF of 6 cfs from July 1 through October 31 are more likely to occur, with naturally occurring inflows having dropped below 6 cfs during the summer months in 10 of 19 years between 2000 and 2018, with flows dropping to less than 2 cfs for some months in three of those years. However, those years had varied water year types, one each in above normal, below normal and critical, and other years with the same water types had higher flows. Therefore, it is not possible to predict what naturally occurring inflow might be in any given year. PG&E is proposing to release the full natural inflow of Grizzly Creek below Grizzly Forebay (i.e., inflow equals outflow), so fish would experience the same natural conditions they would if the project were not present. However, during normal project operation, the natural flow regime below Grizzly Forebay is supplemented under some conditions by water diverted from Lower Bucks Lake. This ability to supplement flows would not be available with the proposed work, as both the Grizzly Powerhouse and tunnel would be offline for maintenance and repairs and the source flows from Lower Bucks will be unavailable during the Lower Bucks Lake dewatering. The impacts of flow reductions to less than 6 cfs would depend on the water year type and the magnitude and duration of the variance. For short-term variations of minor magnitude, that would be experienced under normal or wetter water years, fish would move into deeper habitat to adapt to the flow change, and few impacts would be anticipated. Under longer-term variations of greater magnitude, as would be experienced under dry water years, the impacts would increase. Instream flow models for Grizzly Creek (TRPA 1991) indicate that flows of 2 cfs provide 8 to 12% less habitat for brown trout lifestages (fry, juvenile and adult) than flows of 6 cfs based on 50% exceedance condition accretion flows downstream of the dam in September (selected as a worst-case month). For rainbow trout, this flow reduction would reduce habitat by 14 to 29%. This reduction in habitat would crowd fish into a smaller area but is unlikely to result in large scale fish mortality. If flows were reduced to zero cfs, habitat for brown trout would be reduced by 17 to 23% and for rainbow trout by 26 to 56%. This might result in more mortality for rainbow trout, but the populations of both species would persist. Flow Averaging Period Variance The impact of moving from an instantaneous MIF requirement to a 24-hour MIF requirement is likely negligible. This variance would account for lags between reservoir elevation monitoring and adjustment of pumping rates to match outflow to inflow during May through October 2020, without requiring a variance report for each such occurrence. Trout would not be affected by such short-term variations in flow. From:Bartoo, Aondrea To:Visinoni, Jamie Cc:Lind, Amy -FS; Edlund, Leslie - FS; Lawson, Beth@Wildlife; Lose, Sarah@Wildlife; Joseph, Matthew Subject:Re: \[EXTERNAL\] Updated Review/Approval Request - Bucks Creek Project, FERC No. 619 - Flow and Lake Elevation Variance Date:Thursday, October 10, 2019 7:54:53 AM *****CAUTION: This email was sent from an EXTERNAL source. Think before clicking links or opening attachments.***** The USFWS has reviewed the variance requests for the Lower Bucks Lake Geomembrane retrofit project. The USFWS concurs with all portions of the requests, with the one exception of dewatering Lower Bucks Lake. As this portion of the project is in critical habitat for the Sierra Nevada yellow-legged frog, we would need to analyze the potential impacts to the species through consultation under Section 7 of the ESA prior to providing concurrence. We look forward to future collaboration for the project and are available for any follow-up discussions. I appreciate PG&E's patience while waiting for this response. Thank you! On Mon, Aug 26, 2019 at 12:18 PM Visinoni, Jamie <JNVS@pge.com> wrote: Hello All, Thank you for sharing your questions and concerns regarding the Bucks Creek variance request when we met last week. We have provided more detail on the water management approach in our variance request, please see the updated request below: Pacific Gas and Electric Company (PG&E) plans to perform extensive repairs and maintenance in 2020 at Lower Bucks Lake Dam and Grizzly Forebay Dam, part of PG&E’s Bucks Creek Hydroelectric Project, Federal Energy Regulatory Commission (FERC) Project No. 619. PG&E is requesting U.S. Forest Service (Forest Service), California Department of Fish and Wildlife (CDFW), and the U.S. Fish and Wildlife Department review and approval to temporarily reduce the minimum instream flows (MIF) and minimum lake elevation to levels below those required under Article 13 for Bucks Creek and Grizzly Creek. The request for flow reduction may not be needed but is being submitted as a precautionary measure to ensure construction crews safe access to the perform work on and around the dams. Scope of Construction and Schedule Lower Bucks Dam Work – In a letter dated December 17, 2014, FERC requested that PG&E address several follow-up action items from the 2014 Dam Safety Inspection for the Project. The letter stated that “Severe spalling and surface delamination of concrete has occurred on the downstream abutments and downstream face of the \[Lower Bucks\] dam. The condition should be carefully evaluated, and a repair plan developed.” PG&E performed a condition assessment in 2016 and 2017 which resulted in the installation of a geomembrane liner as one of the recommended repairs. Engineering is underway to address the downstream lining per the 2014 direction. The proposed project includes installation of a geomembrane liner on the upstream face of the dam to reduce seepage and protect the dam from further freeze-thaw damage. To install the liner, Lower Bucks Lake will be completely dewatered, and sediment will be excavated adjacent to the dam to support the geomembrane placement access. The initial drawdown of Lower Bucks Lake will be conducted using a combination of pumping, drafting water through the Grizzly Intake, and exercising the Lower Bucks Dam low level outlet (LLO) until reservoir elevation falls below the minimum operating elevation of the Grizzly Intake. The remaining pool of water in the reservoir will be dewatered using a combination of the LLO and/or pumps. The drawdown and dewatering of Lower Bucks Lake, sediment removal, and geomembrane installation effort will be coordinated with a multi-unit outage scheduled for May to November 2020. During the dewatered period, instream flows downstream of Lower Bucks Dam into Bucks Creek will be satisfied by either: 1) the Milk Ranch Conduit (MRC), which usually flows directly into Lower Bucks Lake but may be re- routed downstream of Lower Bucks Dam, or 2) a bypass gravity flow system from Bucks (Storage) Lake LLO that will be routed downstream of Lower Bucks Dam. The ideal phasing would be to start with MRC into Bucks Creek utilizing flows from the various diversions; once those flows begin to recede and approach the Bucks Creek required MIF, the system will be switched over to the Bucks Storage LLO gravity system; then finally towards the end of the work, based on a calculation of storage volume in Three Lakes, the system would by switched back to MRC for the remainder of the work. This approach provides a redundancy in the system for the duration of work. Grizzly Forebay/Dam Work – Logs and woody debris build up at the Grizzly Forebay overpour spillway during the wet season. Some of these have become waterlogged and have sunk, accumulating upstream of the dam. This project proposes to wet dredge woody debris and accumulated sediment from the reservoir adjacent to the LLO and the Bucks Powerhouse intake structure. This accumulated material impacts both the intake and LLO. The sediment drawn into the intake is causing deterioration to the Bucks Powerhouse runners creating increased maintenance. Debris build up may also be drawn into the LLO which could affect its reliability to provide required instream flow releases downstream of the structure. PG&E has identified May to November 2020 as the potential outage window for the dual Bucks/Grizzly Powerhouses to support this work. License Requirement License Article 13 requires, in part, that PG&E maintain a minimum instream flow in Bucks Creek below the Lower Bucks Dam and from Grizzly Forebay to Grizzly Creek. Minimum streamflows are: (1) Minimum streamflows from Lower Bucks Lake to Bucks Creek: Flow, in cubic feet Period per second (cfs) November 1 through April 30 4 cfs May 1 through June 30* 8 cfs July 1 through October 31 6 cfs (2) Minimum streamflows from Grizzly Forebay to Grizzly Creek: Flow, in cubic feet Period per second (cfs) November 1 through April 30 4 cfs May 1 through June 30* 8 cfs July 1 through October 316 cfs License Article 13 also requires PG&E maintain a minimum water elevation for all lakes. The minimum elevation for Lower Bucks Lake is 4,966 feet. Schedule for Temporary Flow and Reservoir Elevation Variances Variance Bucks Creek To ensure safe and efficient constructability, cost, and schedule, PG&E is stst seeking a temporary flow variance of 6 cfs from June 1 through July 1. A flow of 6 cfs will be achieved through the bypass piping system from Bucks Lake to Bucks Creek and may be augmented with water from the Milk Ranch Conduit (MRC), if available. If enough water is available through the MRC, PG&E expects to be able to achieve the License required MIF of 8 cfs. In addition to the flow variance, PG&E requests the 24-hour average of the flow (mean daily flow) be used for minimum stream flow measurement and reporting for May 1 through November 1, 2020. PG&E will average all the instantaneous readings from midnight of one day to 11:59 pm of the next day. Flow monitoring will be achieved by installing a temporary flow meter on the bypass piping system. Grizzly Creek Variance To support the debris and sediment removal work, a pump system will be deployed to maintain a consistent lake elevation. PG&E is seeking a variance from July 1 through November 1, 2020 to allow flow releases below Grizzly Dam to match the natural inflow into the reservoir, which may drop below the license required 6 cfs depending on water year. In addition to the flow variance, PG&E requests the 24-hour average of the flow (mean daily flow) be used for minimum instream flow measurement and reporting for July 1 through November 1, 2020. PG&E will average all the instantaneous readings from midnight of one day to 11:59 pm of the next day. Flows will be monitored and recorded at NF22. Adjustments to pumping will be made daily to maintain the reservoir elevation, whereby generally matching inflow to outflow. Lower Bucks Lake Water Elevation Variance PG&E requests a variance to the minimum elevation for Lower Bucks Lake, the lake will be completely dewatered for the majority of the outage between May 1 to November 1 of 2020. Biological Resource Evaluation Bucks Creek Minimum Instream Flow Variance In the event of a very dry year that results in June flows of less than 2 cfs in the MRC, flow in Lower Bucks Creek could drop below the MIF of 8 cfs, to as low as 6 cfs. Based on surveys conducted during relicensing (PG&E 2018), Lower Bucks Creek is inhabited by rainbow and brown trout, with brown trout being dominant at the upstream end of the creek, and rainbow trout being dominant further downstream. There are no special status aquatic species known from this stream. All lifestages of rainbow trout (adult, juvenile, fry and spawning) are likely to be present in June, although spawning may be complete by that time, and alI lifestages of brown trout, except spawning would be present. An instream flow study was prepared for Lower Bucks Creek (Thomas R. Payne and Associates 1991. Instream Flow Study for Milk Ranch, Bucks, and Grizzly Creeks. Bucks Creek Project (FERC 619). Prepared for PG&E). Based on this study, a flow reduction from 8 cfs to 6 cfs would result in a reduction in habitat for rainbow trout of 11 % for fry, 15% for juveniles, and 6% for adults. Spawning habitat would be reduced by 45%, if spawning has not completed by that time. Habitat reductions for brown trout would generally be less, ranging from 3% for juveniles to 7% for adults. For all lifestages except rainbow trout spawning, the habitat reduction would be minor and would adjust the timing of the License required MIF reduction from 8 to 6 cfs forward by up to 4 weeks. This would have minimal to no effect on the abundance or health of these fisheries. For rainbow trout spawning, the effect might be more pronounced if redds were still active at the time of the flow reduction, and if redds were placed relatively high in the channel. Flow Averaging Period Variance The impact of moving from an instantaneous MIF requirement to a 24-hour MIF requirement is likely negligible. This variance would allow flows to drop below 6 cfs during a brief period (a couple of hours during any given day) during May through October 2020, without requiring a variance report for each such occurrence. Trout would not be affected by such short-term variations in flow. Lower Bucks Lake Minimum Pool Variance As described above, Lower Bucks Lake will be completely dewatered. PG&E is working with the California Department of Fish and Wildlife (CDFW) to develop a plan for conducting a fish rescue and to develop a restocking plan. To the extent a fish rescue may safely be implemented, PG&E does not expect the fish rescue to provide a biological/environmental benefit. Fish that are rescued will likely be moved to Bucks Lake (Storage), where they would be available to anglers, but will not appreciably increase fish populations (or angler catch-per-unit-effort) in Bucks Lake given the much smaller size of Lower Bucks Lake and the proportion of fish the crews will likely be able to safely rescue. All fish that are not rescued are expected to perish. PG&E and CDFW are also working together to develop a restocking plan for Lower Bucks Lake that will be implemented after the lake refills. This plan will be focused on restocking rainbow trout over a range of sizes. Bucks Lake supports the same species of fish as Lower Bucks Lake. Other fish species will gradually recolonize Lower Bucks Lake, but relicensing studies found that entrainment rates are low in Bucks Lake, and therefore, this is expected to take several years. Lower Bucks Lake and the portion of Bucks Creek immediately downstream of Lower Bucks Dam are within designated critical habitat for Sierra Nevada yellow-legged frog SNYLF), listed as endangered under the Endangered Species Act. Surveys during relicensing did not identify any occurrences of this species in either of these areas. The nearest SNYLF observation was in Bear Ravine located in a drainage about 0.3 miles north of Lower Bucks Dam. The flow and water level variances associated with this project would not adversely affect habitat values for this species. A separate biological assessment is being prepared for submission to the U.S. Fish and Wildlife Service regarding the potential impacts of this project on SNYLF and its habitat, but no impacts are anticipated. Grizzly Creek Flow Variance Grizzly Creek has the same fish assemblage as Bucks Creek, rainbow trout and brown trout, with no special status aquatic species. As with Bucks Creek, brown trout dominate the fish community closer to the dam, while rainbow trout are dominant at the more downstream end of the reach. Grizzly Creek receives flow from Lower Bucks Lake when the Grizzly Powerhouse is in operation, but both the Grizzly powerhouse and the tunnel will be offline, and so flow from Lower Bucks Lake will not be available to supplement natural inflow. A flow reduction below the current MIF of 8 cfs in May and June is unlikely to occur based on either the unimpaired flow analysis done as part of relicensing or a review of hydrology since 2000. Flow reductions below the current MIF of 6 cfs from July 1 through October 31 are more likely to occur, with naturally occurring inflows having dropped below 6 cfs during the summer months in 10 of 19 years between 2000 and 2018, with flows dropping to less than 2 cfs for some months in three of those years. However, those years had varied water year types, one each in above normal, below normal and critical, and other years with the same water types had higher flows. Therefore, it is not possible to predict what naturally occurring inflow might be in any given year. PG&E is proposing to release the full natural inflow of Grizzly Creek below Grizzly Forebay (i.e., inflow equals outflow), so fish would experience the same natural conditions they would if the project were not present. However, during normal project operation, the natural flow regime below Grizzly Forebay is supplemented under some conditions by water diverted from Lower Bucks Lake. This ability to supplement flows would not be available with the proposed work, as both the Grizzly Powerhouse and tunnel would be offline for maintenance and repairs and the source flows from Lower Bucks will be unavailable during the Lower Bucks Lake dewatering. The impacts of flow reductions to less than 6 cfs would depend on the water year type and the magnitude and duration of the variance. For short-term variations of minor magnitude, that would be experienced under normal or wetter water years, fish would move into deeper habitat to adapt to the flow change, and few impacts would be anticipated. Under longer-term variations of greater magnitude, as would be experienced under dry water years, the impacts would increase. Instream flow models for Grizzly Creek (TRPA 1991) indicate that flows of 2 cfs provide 8 to 12% less habitat for brown trout lifestages (fry, juvenile and adult) than flows of 6 cfs based on 50% exceedance condition accretion flows downstream of the dam in September (selected as a worst-case month). For rainbow trout, this flow reduction would reduce habitat by 14 to 29%. This reduction in habitat would crowd fish into a smaller area but is unlikely to result in large scale fish mortality. If flows were reduced to zero cfs, habitat for brown trout would be reduced by 17 to 23% and for rainbow trout by 26 to 56%. This might result in more mortality for rainbow trout, but the populations of both species would persist. Flow Averaging Period Variance The impact of moving from an instantaneous MIF requirement to a 24-hour MIF requirement is likely negligible. This variance would account for lags between reservoir elevation monitoring and adjustment of pumping rates to match outflow to inflow during May through October 2020, without requiring a variance report for each such occurrence. Trout would not be affected by such short-term variations in flow. PG&E requests your review and concurrence as soon as possible. Thank you for your timely attention to this matter. All concurrence emails and/or letters we receive will be included in our filing with FERC. PG&E staff is available to discuss this variance request in more detail, if needed. If you have any questions, please call: General Questions – Jamie Visinoni, 530-215-6676 Project/Engineering – Jeff Jukkola, 530-624-8640 Biological Review – Larry Wise, 925-415-6353 Thank you, Jamie Visinoni Hydro License Coordinator | Power Generation Pacific Gas and Electric Company d: N/A | m: (530) 215-6676 | e: jamie.visinoni@pge.com -- A. Leigh Bartoo Fish and Wildlife Biologist Bay-Delta Fish and Wildlife Office U.S. Fish and Wildlife Service 650 Capitol Mall, 8-300 Sacramento, CA 95814 916-930-5621