Overview of Project Description - Middle Fork American River ...

M i d d l e F o r k A m e r i c a n R i v e r P r o j e c tFrench Meadows reservoirHell Hole reservoirThe backbone of theMFP is the captureand storage of water inFrench Meadows andHell Hole reservoirs.ProjectDescriptionTHE MFP SERVES AS A MULTI-PURPOSE WATER SUPPLYand hydro-generation project designed to conserve and controlwaters of the Middle Fork American River, the RubiconRiver, and several associated tributary streams. The MFP is locatedwithin the Middle Fork American River Watershed (Watershed)at elevations ranging from approximately 1,100 feet to 5,300 feet.Water for hydroelectric generation and consumptive use is divertedand stored under permits and licenses issued by the SWRCB.The MFP seasonally stores and releases water to meet consumptivedemands within western Placer County and to generate power for theCalifornia electrical grid. Water for consumptive purposes is released fromthe MFP and re-diverted at two locations: (1) the American River PumpStation, located on the North Fork American River near the City of Auburn;and (2) Folsom Reservoir. Both points of re-diversion are downstream of theMFP facilities and neither is part of the MFP as defined in the FERC ProjectSupporting Document BSD BDetailedExistingProjectDescription

M i d d l e F o r k A m e r i c a n R i v e r P r o j e c tPlacer County Farmer’s MarketThe MFP benefits the people of Placer County byproviding water and electricity.a well-lit Placer County communityLicense. PCWA’swater rights and watersupply agreementscurrently allow for theconsumptive use ofup to 120,000 ac‐ftof MFP water perWater fountainat Local Parkyear. Consumptivewater supplied byPCWA is used tomeet municipal, industrial, and agricultural demands.Hydroelectric power from the MFP is produced atfive Project powerhouses with a combined nameplategenerating capacity of approximately 224 MW. Thetotal annual flow through the MFP and the resultingtotal annual generation are highly variable. The MFPproduces an average of 1,030,000 MWh annually onmean generation flows of 452,000 ac-ft. The highestannual generation was in 1983, a wet water year, whenthe MFP produced approximately 1,815,000 MWh onflows of 714,400 ac-ft. The lowest annual generationwas in 1977, a critically dry water year, when the MFPonly produced 211,000 MWh on flows of 75,000 ac-ft.Project FacilitiesThe MFP diverts, stores, and transports waterthrough a series of stream diversions, reservoirs, waterconveyance systems, and powerhouses before it isreleased back into the Middle Fork American Riverbelow Oxbow Powerhouse, approximately 29 milesupstream of Folsom Reservoir. Instream flow releasesbelow each diversion are made in accordance withFERC license requirements. All electricity generatedby the MFP is delivered to Pacific Gas and Electric’s(PG&E’s) transmission system at Project switchyardsand substations, typically located near powerhouses.PG&E’s transmission system is not part of the MFP.The backbone of the MFP is its two principal waterstorage reservoirs, French Meadows and Hell Hole. Thesereservoirs are located on the Middle Fork AmericanRiver and the Rubicon River, respectively, and have acombined gross storage capacity of 342,583 ac-ft.Starting at the highest elevation of the MFP, wateris diverted from Duncan Creek at the Duncan CreekDiversion and routed through the 1.5 mile-longDuncan Creek-Middle Fork Tunnel into FrenchMeadows Reservoir (134,993 ac-ft of gross storage).Flows in the Middle Fork American River arecaptured and stored in French Meadows Reservoir alongwith diversions from Duncan Creek. From FrenchMeadows Reservoir, water is transported via the 2.6mile-long French Meadows-Hell Hole Tunnel, passedthrough the French Meadows Powerhouse (installedgenerating capacity of 15.3 MW) and released intoHell Hole Reservoir (207,590 ac-ft of gross storage).Flows in the Rubicon River are captured and storedin Hell Hole Reservoir along with water releasedfrom French Meadows Reservoir through FrenchMeadows Powerhouse. Water released from Hell HoleReservoir into the Rubicon River to meet instreamflow requirements first pass through the Hell Hole10

Rubicon RiverM i d d l e F o r k A m e r i c a n R i v e r P r o j e c tPCWA PowerHeadquarters">Middle ForkAmerican RiverWatershedAreaEnlargedBelowFORESTHILLBlacksmith FlatRoadForesthill RoadNorth Fork of Middle Fork American RiverMIDDLE FORKAMERICAN RIVERWATERSHEDMosquito Ridge RoadMiddle ForkInterbay#*Middle ForkPowerhouse%Duncan CreekRobinsonFlatDuncan CreekDiversionFR 22Middle Fork American River%French MeadowsReservoirFrenchMeadowsDamNorth Fork/South ForkLong CanyonDiversionsDuncan Creek - Middle ForkTunnelFR 2South Fork Long CanyonNorth Fork Long Canyon%#*#*French Meadows - Hell HoleTunnelFrench MeadowsPowerhouseHell HoleReservoirHell Hole DamHell HolePowerhouseRalston - OxbowTunnelOxbowPowerhouse%#*RalstonAfterbay#*RalstonPowerhouseFR 23%Long CanyonMiddle Fork - RalstonTunnelHell Hole - Middle ForkTunnelSouth Fork Rubicon RiverFR 2EllicottBridgePowerhouse (installed generating capacity of 0.73 MW),which is located at the base of Hell Hole Dam.From Hell Hole Reservoir, water is also transportedvia the 10.4 mile-long Hell Hole-Middle ForkTunnel, passed through the Middle Fork Powerhouse(installed generating capacity of 122.4 MW) andreleased into the Middle Fork Interbay (175 ac-ftof gross storage). Between Hell Hole Reservoir andMiddle Fork Powerhouse, water is diverted fromthe North and South Forks of Long Canyon creeksdirectly into the Hell Hole-Middle Fork Tunnel.Water diverted from these creeks into the Hell Hole- Middle Fork Tunnel can either be stored in Hell HoleReservoir or be used to augment releases from HellHole Reservoir to the Middle Fork Powerhouse.Flows from the Middle Fork American River(including instream flow releases from French MeadowsReservoir) are captured at Middle Fork Interbay alongwith water released from Hell Hole Reservoir throughMiddle Fork Powerhouse. From Middle Fork Interbay,water is transported via the 6.7 mile-long Middle Fork-Ralston Tunnel, passed through the Ralston Powerhouse(installed generating capacity of 79.2 MW) and releasedinto the Ralston Afterbay (2,782 ac-ft of gross storage).Flows from the Middle Fork American River (includinginstream releases from Middle Fork Interbay) and flowsfrom the Rubicon River (including instream releases fromHell Hole Reservoir) are captured in Ralston Afterbayalong with water transported from Middle Fork Interbaythrough Ralston Powerhouse. From Ralston Afterbay,water is transported via the 400 foot-long Ralston-Oxbow Tunnel, passed through the Oxbow Powerhouse(installed generating capacity of 6.1 MW) and releasedfrom the MFP to the Middle Fork American River.In addition to these major water and power facilities,the MFP includes 35 Project roads (totaling almost 18miles) and 10 Project trails (totaling approximately 0.5miles). These roads and trails are used almost exclusively11

M i d d l e F o r k A m e r i c a n R i v e r P r o j e c tHell Hole boat rampProject recreation facilities and reservoirssupport a variety of recreational activities.French MeadowscampgroundOxbow put-inby PCWA to access Projectfacilities. The Project roads andtrails represent less than 1% of thetotal miles of roads and trails inthe Watershed. There are also over6 miles of Project powerlines and communication lines,which provide power to operate Project equipmentand allow communication between Project facilities. Inaddition, numerous smaller facilities and features supportMFP operations including flow gaging stations andweirs, photovoltaic poles, microwave reflectors and radiotowers, sediment disposal sites, generator and storagebuildings, operator cottages, a maintenance shop, adormitory facility, and security and public safety fences.The MFP also includes 21 developed recreationfacilities to enable public access to public lands andProject reservoirs. The developed Project recreationfacilities are concentrated around French MeadowsReservoir, Hell Hole Reservoir, South Fork LongCanyon Diversion Pool, and Ralston Afterbay. PCWAis responsible for operation and maintenance of thesefacilities. The Project recreation facilities augmentother recreation facilities in the Watershed operatedby the TNF and ENF and the California Departmentof Parks and Recreation (DPR).Project OperationThe MFP has been operated for over 40 yearsby PCWA as a multi-purpose project to benefitthe people of Placer County. The MFP is operatedwith respect to four objectives, as follows:• Meet FERC license requirements that protectenvironmental resources and provide for recreation;• Meet the consumptive water demandsof western Placer County;• Generate power to help meet California’s energydemand and provide valuable support servicesrequired to maintain the overall quality andreliability of the state’s electrical supply system; and• Maintain Project facilities to ensure theircontinued availability and reliability.Project operations for water supply and electric powergeneration are constrained by regulatory and contractrequirements, the physical capacities of the Projectfacilities, and water availability. Regulatory and contractrequirements include conditions imposed by the FERClicense, water rights permits, water delivery contracts,and the existing power purchase contracts with PG&E.Water availability is influenced by carryoverstorage in the Project reservoirs and thetiming and quantity of annual runoff.12

M i d d l e F o r k A m e r i c a n R i v e r P r o j e c tInflow (acre feet x 1,000)9008007006005004003002001000Annual operations are strongly influenced by inflow into the MFP.Typical annual operation of the Project results inthe capture of runoff which is diverted to increasestorage in French Meadows and Hell Hole reservoirsin the winter and spring (filling period), anddrawdown of the reservoirs during the summer, fall,and early winter (release period). Operation of theMFP varies from year-to-year based on the timingand magnitude of spring runoff, which is influencedby the amount of winter snow pack and ambienttemperature conditions, as well as precipitation.During the filling period, flows through the MFPpowerhouses are highly dependent on projected andactual runoff conditions. In drier years, power releasesare minimized during the filling period to increase thevolume of water in storage to meet upcoming summerconsumptive use and peak power demands. In wetteryears, power releases during the filling period areincreased to minimize spills from the reservoirs. In yearswhen minimum storage levels to meet consumptiveJan196719691971197319751977197919811983Energy Typical Demand Seasonal vs Demand Water Pattern DemandEnergy Demand (MW)Water Demand (Acre Feet)FebMarAprAnnual MFP InflowMayJun1985198719891991199319951997199920012003The MFP is operated to meet consumptive water and energydemands.JulAugSepOctNovDecdemands are reasonably assured and the chance of spillingis low, power releases are adjusted through the fillingseason based on the volume of water in storage, projectedrunoff, and current and projected power demands.During the release period, after the reservoirs havereached their maximum storage capacity, monthlyreleases for generation are largely predictable for theremainder of the year. However, daily and hourly releasesfor generation, which respond to demand for electricityand electrical grid reliability, remain highly variable.During the release period, flows are managed to: (1)meet storage and flow license requirements; (2) meetconsumptive water supply requirements; (3) optimizepower generation to meet peak electrical demand; and(4) achieve end-of-year carryover target storage levels.Decisions on the extent of the drawdown and theTypical Weekly Energy Demand and ProductionEnergy productionEnergy demandMon Tue Wed Thu Fri Sat SunThe ability of the hydroelectric project to generate electricityduring periods of peak demand maximizes the value of the MFP.carryover target storage level is based on balancing ofcompeting needs including: (1) providing sufficientempty storage space to minimize potential spills fromthe reservoirs during the next filling period if therunoff is high (wet year); and (2) retaining enoughwater in storage to ensure that license requirementsand consumptive demands can be met in the followingyear if the next filling period runoff is low (dry year).Water supply operations take priority over powergeneration operations. However, in all but dry years,current water supply demands are easily met as aby-product of power generation. The reason is thatboth consumptive water and electrical demandstend to coincide seasonally and the MFP generallycontrols and releases far more water annually than13

M i d d l e F o r k A m e r i c a n R i v e r P r o j e c tThe Middle Fork and Ralston powerhousesaccount for over 90% of totalMFP power generation.Ralston powerhouseMiddle Fork powerhouseThe heart of the MFPis generation producedat Middle Fork andRalston powerhouses.Critical elements of MFP operations✓ The flexibility to raise and lower water levels (water storage) atFrench Meadows and Hell Hole reservoirs at different rates andtimes throughout the year✓ The ability to release water from storage at the appropriate timeto meet an annual consumptive demand of up to 120,000 ac-ft✓ The ability to maximize generation during periods of highelectrical demand, especially in the summer and fall of dry yearswhen water availability may limit generating opportunities✓ The ability to simultaneously operate the Middle Fork and Ralstonpowerhouses (timing and flow) to maximize peak generationwhile avoiding spills at the Middle Fork Interbay✓ The ability to independently generate at Oxbow Powerhouse(decoupled from operations of the Middle Fork and Ralstonpowerhouses) by using the re-regulation capability of the RalstonAfterbay✓ The ability to shutdown the MFP annually for relatively shortperiods to perform routine maintenancePCWA requires to meet its consumptive water demand. The majority ofPCWA’s consumptive deliveries are withdrawn from Folsom Reservoir,where the United States Bureau of Reclamation (USBR) allows for a 30-day balancing of supply and demand; thus hourly or even daily releasesfrom the MFP do not need to explicitly match consumptive deliveriesfrom Folsom Reservoir. Only the re-diversion of water for consumptivedemand at the American River Pump Station near Auburn (maximum100 cfs) requires hourly MFP system balancing to meet continuousminimum instream flows requirements below the pumping station.The Middle Fork and Ralston powerhouses are the heart of MFPgeneration. These two powerhouses generally run in tandem, using watertransported from Hell Hole Reservoir to RalstonAfterbay. Together the two powerhouses have a ratedcapacity of 201.6 MW and produce about 90%of the MFP annual generation. Although MiddleFork Interbay is located between these powerhouses,Middle Fork Interbay has little ability to re-regulateflows because of its small storage capacity (175 acft).If the flows through the Middle Fork and Ralstonpowerhouses are not matched, Middle Fork Interbaywould be either drained or overtopped very quickly.These powerhouses, running in tandem, are often usedto help maintain reliable operations of the transmissiongrid by fine-tuning the flow of electricity in the grid tobalance supply and demand. When operated to providegrid regulation, flow rates through the powerhousesvary quickly to meet constantly changing energysupply and demand conditions. These powerhouses14

M i d d l e F o r k A m e r i c a n R i v e r P r o j e c tare also frequently block loaded. When block loaded,flows through the powerhouses are usually set atan efficient operating level and run for a prescribednumber of hours per day, depending upon hydrology.French Meadows Powerhouse is used when water ismoved from French Meadows Reservoir to Hell HoleReservoir. It is nearly always operated in block loadedcondition, with the duration of the block of operationset depending on the volume of water to be moved.Ralston Afterbay and Oxbow Powerhouse are thefinal steps in the MFP system. Oxbow Powerhousefrequently runs in tandem with Middle Fork and Ralstonpowerhouses. Presently, water is released from OxbowPowerhouse to the Middle Fork American River at thesame rate it enters Ralston Afterbay. However, RalstonAfterbay has sufficient operational storage capacity(about 1,200 ac-ft out of 2,782 ac-ft gross) to allowOxbow Powerhouse to operate independently of MiddleFork and Ralston powerhouses for several hours at atime. This independent operational flexibility is usedto meet the ramping rate requirement downstream ofOxbow Powerhouse, and to make weekend releasesfor whitewater rafting without requiring operationof the Middle Fork and Ralston powerhouses.Testing and MaintenanceTo maintain and protect system reliability,PCWA conducts annual inspections, testing, andmaintenance of Project facilities. Annual maintenanceis scheduled at a time when the work can beexpeditiously completed (during favorable flow andweather conditions) and have the least effect onwater supply deliveries and power production.These activities typically occur for facilities in the lowerProject area beginning in late September, and require thatthe lower MFP powerhouses (Middle Fork, Ralston, andOxbow) be taken out-of-service for 3-6 weeks. Duringthe fall maintenance period, Middle Fork Interbay andRalston Afterbay water levels are lowered to allow accessto the facilities. Consumptive demands and instreamflow requirements downstream of Oxbow Powerhouseduring the fall outage are typically met by increasing flowreleases from Hell Hole Reservoir into the Rubicon River.Inspection, testing, and the maintenance of facilities inthe upper Project area (i.e., French Meadows and HellHole powerhouses), typically occur during the spring,once the roads to the Project facilities are passable.Sediment removal atNorth Fork Long Canyon Diversion PoolOngoing maintenance isessential for system reliability.PCWA also implementsroutine maintenanceactivities within andaround Project facilities to:• Preserve Projectflow and storagecapacities byimplementingsediment anddebris management;Maintenance atInterbay Dam• Protect worker and public health andsafety by implementing vegetationmanagement, pest management, signage,and erosion and rock control measures;• Provide facility access by implementingroad and trail maintenance; and• Protect facility reliability by implementingequipment maintenance, erosion and rockcontrol measures, facility painting, and powerlineand communication line pole replacement.For Project recreational facilities, PCWA has ongoingagreements with the TNF and ENF under whichit provides the financial resources necessary to supporta portion of the operation and restoration of thesefacilities by the respective National Forests. PCWA alsohas a cost-sharing agreement with the TNF and ENF tocontribute funding for a portion of road maintenanceon non-Project Forest Service roads used by PCWA.15