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Merced River

The Merced River is a westward-flowing tributary of the San Joaquin River originating on the south side of Mount Lyell in the Sierra Nevada at an elevation of 13,114 feet and descending through Yosemite National Park before reaching its confluence in California's Central Valley.^[1] Its course traverses glacially sculpted canyons, alpine meadows, and Yosemite Valley, where it supports exceptional scenic, geological, and recreational values as a designated National Wild and Scenic River since 1987.^[2] The river's watershed, spanning about 1,300 square miles, drains primarily within Yosemite National Park and adjacent lands, contributing to regional hydrology with average flows around 355 cubic feet per second at key monitoring points like Happy Isles.^[3]^[4] Ecologically, the Merced sustains diverse native and endemic species, including trout populations and amphibians like the limestone salamander, while its free-flowing segments preserve pristine Sierra Nevada fisheries amid ongoing restoration efforts to mitigate human-induced alterations such as channelization and flood damage.^[1]^[5] Below the park, the river faces modifications including dams like New Exchequer Dam forming Lake McClure for irrigation and flood control, which interrupt its natural flow and spark debates over water allocation between agricultural demands and environmental preservation.^[6] Designated segments emphasize wild characteristics upstream, transitioning to recreational uses downstream, underscoring the river's role in balancing conservation with hydropower and irrigation needs in a water-scarce region.^[7]

Physical Characteristics

Course and Hydrology

The Merced River originates on the south side of Mount Lyell in Yosemite National Park at an elevation of 13,114 feet (3,998 m), where its headwaters form from several forks including the Red Peak Fork, Merced Peak Fork, Triple Peak Fork, and Lyell Fork.^[1] These upper reaches flow northwest through glacially carved terrain, descending through steep canyons and passing features such as Nevada Fall and Vernal Fall before entering Little Yosemite Valley and subsequently broadening into the floor of Yosemite Valley.^[4] ^[8] The river's total length measures 145 miles (233 km).^[9] Upon exiting Yosemite Valley near El Portal, the Merced River enters a narrow, steep-sided gorge with an average gradient of 70 feet per mile (13 m/km), receiving inflows from principal tributaries such as Illilouette Creek, Tenaya Creek, Yosemite Creek, Echo Creek, and Sunrise Creek within the park, and the larger South Fork Merced River downstream near Briceburg.^[4] ^[10] The South Fork, the river's largest tributary at 43 miles (69 km) long, drains Yosemite's southern watersheds including Wawona.^[10] Beyond the gorge, the river traverses foothills regulated by structures like the Crocker-Huffman Diversion Dam before impounding in Lake McClure behind New Exchequer Dam at approximately 900 feet (274 m) elevation.^[1] In its lower course, the Merced River flows past Merced Falls Dam and across the San Joaquin Valley floor, where it is joined by minor tributaries like Dry Creek, before reaching its mouth at the San Joaquin River near Stevinson in Merced County.^[11] ^[12] The Merced River's watershed spans 1,266 square miles (3,280 km²), with elevations ranging from 52 feet (16 m) at the valley floor to 13,090 feet (3,990 m) in the headwaters, primarily fed by Sierra Nevada snowmelt leading to peak discharges in spring and early summer.^[13] Flows are heavily regulated by reservoirs including Lake McClure for flood control, irrigation via the Merced Irrigation District, hydropower, and water supply, which attenuate natural peaks and sustain baseflows; for instance, USGS gauges record maximum discharges exceeding 10,000 cubic feet per second (cfs) during floods at upper sites like Happy Isles.^[14] ^[6] ^[15]

Watershed

The Merced River watershed encompasses approximately 1,280 square miles (3,300 km²) on the western slope of the central Sierra Nevada in California, draining portions of Mariposa, Madera, and Merced counties before joining the San Joaquin River.^[16] Elevations within the basin range from about 52 feet (16 m) near the river's mouth to over 13,000 feet (4,000 m) at the headwaters.^[13] The watershed is bordered to the north by the Tuolumne River basin and to the south by the upper San Joaquin River drainage, with the upper portion largely within Yosemite National Park and Sierra National Forest.^[17] Major tributaries include the South Fork Merced River, the largest contributor originating in Yosemite National Park near Wawona and joining the main stem below Yosemite Valley; the North Fork Merced River; and upper branches such as the Triple Peak Fork, Lyell Fork, Red Peak Fork, Illilouette Creek, Tenaya Creek, Yosemite Creek, Bridalveil Creek, and Poohoo Creek.^[10] ^[1] Lower tributaries like Dry Creek add drainage from the surrounding foothills before the river reaches the Central Valley.^[12] These tributaries collectively supply snowmelt-dominated flows, with the basin's hydrology driven by seasonal precipitation ranging from heavy winter snowpack in the high Sierra to rainfall in the lower elevations.^[18] Land cover in the watershed varies markedly by elevation and location: the upper basin, comprising about 30% of the area within Yosemite National Park, consists primarily of granitic terrain, coniferous forests, alpine meadows, and protected wilderness with minimal human modification.^[4] In contrast, the lower watershed transitions to foothill oak woodlands and intensive agricultural lands in the San Joaquin Valley, including croplands for almonds, tomatoes, and dairy operations, alongside urban development around Merced city.^[16] This downstream predominance of agriculture influences sediment transport and water quality, with historical logging and current farming contributing to nutrient loading despite upstream protections.^[16] Overall, the basin's undeveloped headwaters provide high-quality baseflow, while land use pressures in the valley necessitate management for flood control and groundwater recharge.^[6]

Geology

The Merced River traverses the Sierra Nevada batholith, predominantly over granitic rocks intruded during the Cretaceous period approximately 80 to 130 million years ago, when magma from subducting oceanic plates beneath the North American continent crystallized into coarse-grained plutons composed mainly of quartz, plagioclase feldspar, and potassium feldspar.^[19] These intrusions occurred into older Precambrian and Paleozoic metamorphic basement rocks, fragments of which outcrop sporadically along the river's course, particularly in the steep walls of the Merced Gorge east of El Portal where metavolcanic and metasedimentary sequences date back over 500 million years.^[12] The river's upper reaches in the high Sierra expose fresh granodiorite and tonalite variants, while downstream segments incorporate Quaternary glacial till and alluvium derived from erosion of these resistant lithologies, forming sandy-loam textured deposits in broader valleys.^[20] Yosemite Valley, through which the Merced flows centrally, exemplifies combined fluvial and glacial modification of this granitic terrain, with the river's pre-glacial antecedent drainage deepened by multiple Pleistocene glaciations that amplified U-shaped cross-profiles and hanging valleys via ice abrasion and plucking.^[21] The trunk Merced Glacier, advancing from the Sierra crest, scoured the valley floor to depths exceeding 2,000 feet in places, depositing moraines and erratics while overtopping features like Vernal and Nevada Falls; subsequent fluvial incision by the river has since excavated stair-step cascades and potholes in the bedrock.^[22] Post-glacial retreat around 16,000 years ago initiated meandering in the alluvial reach from Happy Isles to the valley's west end, where the river maintains a dynamic, mid-elevation floodplain amid exfoliated granite domes and sheer cliffs shaped by joint-controlled fracturing and unloading.^[23]^[24] Tectonic uplift of the Sierra Nevada, driven by isostatic rebound following Late Cenozoic erosion and faulting along its eastern escarpment, elevated the Merced's watershed to over 13,000 feet at its headwaters near Mount Lyell, enhancing gradient-driven downcutting that predates heavy glaciation.^[25] Evidence from drainage patterns suggests pre-glacial reorganization contributed to initial valley incision, with the river's path stabilizing through granitic resistance that preserves landforms like the upper Merced Canyon's 2,000-foot-deep, narrow trench.^[26] In the lower basin, the river crosses Pleistocene terrace deposits and Holocene alluvium, reflecting ongoing aggradation from Sierra-derived sediments amid regional subsidence in the Great Valley.^[20]

Ecology and Biology

Flora and Fauna

The Merced River's riparian corridors and associated meadows support diverse vegetation adapted to periodic flooding and high groundwater levels, including shrubs and trees that stabilize banks and provide habitat connectivity. Key riparian species include the rare Sierra sweet bay (Myrica hartwegii), which occurs exclusively on downstream sand bars and riverbanks from Wawona southward.^[27] Endangered and rare plants in the watershed encompass Merced clarkia (Clarkia lingulata), a state-listed endangered annual herb; Yosemite onion (Allium yosemitense); Congdon’s wooly sunflower (Eriophyllum congdonii); Congdon’s lewisia (Lewisia congdonii); and shaggyhair lupine (Lupinus spectabilis), the latter near Lake McClure.^[27] ^[28] These species thrive in meadow edges and floodplain habitats influenced by river dynamics, though visitor trampling and erosion have degraded some areas.^[5] Aquatic and semi-aquatic fauna in the Merced River include native fish confined to lower reaches below approximately 4,000 feet elevation due to natural waterfalls blocking upstream migration, such as California roach (Hesperoleucus symmetricus), Sacramento pikeminnow (Ptychocheilus grandis), hardhead (Myllokunmingia sikanniensis), and riffle sculpin (Cottus gulosus).^[29] ^[27] Introduced non-native species, including rainbow trout (Oncorhynchus mykiss), brown trout (Salmo trutta), brook trout (Salvelinus fontinalis), smallmouth bass (Micropterus dolomieu), and bluegill (Lepomis macrochirus), have been stocked historically since 1877, totaling over 33 million fish by 1990, altering native ecosystems through competition and predation.^[29] The federally threatened Central Valley Distinct Population Segment of steelhead (Oncorhynchus mykiss) persists in lower watershed segments, dependent on unimpeded flows for spawning.^[30] Amphibians tied to the river include the endemic limestone salamander (Hydromantes brunus), restricted to limestone outcrops in the Merced River canyon with only 15 known populations, eight protected under the Wild and Scenic Rivers Act.^[27] Riparian zones also sustain riparian-dependent reptiles and amphibians, though some like the foothill yellow-legged frog have been locally extirpated.^[31] Terrestrial mammals utilizing riverine habitats include mule deer (Odocoileus hemionus), which forage in meadows and riparian edges, alongside general Yosemite species like black bears (Ursus americanus) that access water and forage along the corridor.^[27] ^[32] Avian diversity features over 260 species park-wide, with riparian specialists such as bald eagles (Haliaeetus leucocephalus) nesting along the Merced, great gray owls (Strix nebulosa), and peregrine falcons (Falco peregrinus), supported by the river's prey base including fish and rodents.^[33] ^[27] Rare bats like the spotted bat (Euderma maculatum) inhabit meadow-riparian interfaces.^[27] Overall, the ecosystem hosts nearly all 200 Sierra Nevada bird species and diverse vertebrates reliant on floodplain connectivity.^[27]

Ecological Dynamics and Threats

The Merced River's ecological dynamics are driven by its seasonal hydrology, with high spring snowmelt flows fostering sediment deposition, channel migration, and riparian habitat renewal, while low summer baseflows concentrate aquatic productivity in pools and riffles supporting invertebrate communities that form the base of the food web for fish like Chinook salmon (Oncorhynchus tshawytscha).^[34]^[35] These processes sustain fall-run Chinook salmon populations in the lower watershed, where adults spawn in gravel beds during October–December, relying on pulse flows for egg incubation and juvenile rearing amid cooler, oxygenated waters.^[12] Riparian vegetation, including willows and cottonwoods, responds to flood pulses by colonizing inner bends, stabilizing banks and providing shade that moderates water temperatures critical for salmonid survival, though restoration sites show reduced undercut banks and woody debris compared to unaltered Central Valley streams, limiting overhead cover and prey availability.^[36]^[37] Threats to these dynamics primarily stem from upstream dams and diversions, such as those operated by the Merced Irrigation District, which reduce peak flows by up to 50–70% below natural levels, fragmenting habitat and elevating summer water temperatures above 20°C, lethal thresholds for juvenile salmon rearing and migration.^[38]^[39] Low flows during droughts, as in 2022 when sections ran dry, exacerbate dewatering of spawning gravels and strand juveniles, while historical mining and levee failures have degraded channel complexity, reducing side-channel habitats essential for salmon refugia.^[40]^[41] Water quality impairments include elevated salinity, organic matter, and nutrients from agricultural runoff and wastewater discharges, with incidents like the 2023 Gallo winery spill of 90,000 gallons contributing to localized pollution spikes that stress aquatic biota.^[16]^[42] Climate-driven shifts, including reduced Sierra Nevada snowpack, intensify these pressures by shortening high-flow periods needed for scour and gravel recruitment, potentially collapsing salmon runs without adaptive flow management.^[43]

History

Geological and Prehistoric Formation

The Merced River's geological formation is tied to the tectonic evolution of the Sierra Nevada, where uplift initiated around 10 million years ago during the Miocene, elevating the range and enabling river downcutting into granitic bedrock primarily formed 85 to 105 million years ago in the Cretaceous period.^[19]^[44] Prior to major glaciations, the ancestral Merced River incised a proto-valley through pre-glacial erosion, accelerated by westward tilting of the Sierra Nevada approximately 5 million years ago and structural weaknesses like bedrock joints, with evidence indicating significant deepening occurred before Pleistocene ice ages.^[45]^[25] During the Pleistocene, multiple glaciations profoundly shaped the river's course, as alpine glaciers originating in the high Sierra advanced down the Merced canyon, eroding U-shaped valleys, cirques, and stair-step cascades while depositing moraines and till; key stages include the Sherwin (pre-700,000 years ago), Tahoe (~150,000–130,000 years ago), Tenaya, and the most recent Tioga glaciation, which reached its maximum extent 15,000 to 20,000 years ago.^[21]^[44] The Tioga advance filled Yosemite Valley to depths of up to 1,200 meters, with a trunk glacier extending from the river's headwaters through the valley and beyond, overtopping features like Vernal and Nevada Falls; post-glacial isostatic rebound and continued fluvial erosion by the Merced have since refined the landscape, maintaining the river's path along glacial troughs and fracture-guided channels.^[46]^[1]^[47] Prehistoric sedimentary records along the lower Merced, such as Pliocene-Pleistocene deposits, reflect the river's role in basin filling and incision, with units like the Merced Formation documenting shifting depositional environments amid ongoing tectonic and climatic influences.^[48]

Indigenous and Early Human Use

The Southern Sierra Miwok, particularly the Ahwahneechee subgroup in Yosemite Valley, maintained continuous occupation along the Merced River for approximately 4,000 to 5,500 years prior to European contact, with archaeological evidence of broader human presence in the Yosemite region dating back nearly 10,000 years, including hunting with spears and atlatls and seed processing on grinding stones.^[49]^[50] In the Merced River canyon near El Portal, sites indicate habitation as early as 9,500 years ago, reflecting adaptation to the river's riparian zones for settlement and resource extraction.^[51] These groups, sometimes incorporating Paiute elements, established villages directly along the riverbanks, constructing conical lodges known as umachas from cedar bark and poles, with sites such as Wakalmata named for the Merced itself, termed Wa-kal-la meaning simply "the river" in their language.^[52]^[53] Indigenous use centered on the river's ecological productivity, with fishing for migratory salmon (Oncorhynchus spp.) and steelhead (Oncorhynchus mykiss) that ascended unimpeded to Yosemite Valley and Wawona, supporting family-based fishing camps and weirs documented in pre-contact patterns and later treaty-era accounts.^[54]^[55] Settlements exploited the river for transportation via canoes or foot trails, water supply, and gathering of aquatic plants, while seasonal migrations shifted populations downslope to the milder Merced canyon in winter for fishing and hunting, contrasting summer uplands for acorn processing and big game.^[56]^[57] Landscape management through low-intensity fires maintained open oak savannas near the river, enhancing visibility for hunting deer and facilitating acorn harvests critical to Miwok diet, with obsidian tools traded from Mono neighbors aiding riverine activities like fish spearing.^[58]^[59] Lower reaches of the Merced, in the Central Valley foothills, saw complementary use by Yokuts bands, who settled along rivers for similar fishing and irrigation-dependent gathering, though Miwok influence dominated the upper watershed.^[60] These practices sustained populations estimated in the hundreds per valley group, reliant on the river's hydrology for seasonal floods that enriched floodplains, without evidence of large-scale alteration prior to contact.^[61]

European Exploration and Modern Settlement

The first documented European expeditions into the Merced River region occurred during the Spanish colonial period, with Lieutenant Gabriel Moraga leading a reconnaissance party eastward from the San Joaquin River toward the Sierra Nevada foothills in the fall of 1806, approaching but not fully entering the Yosemite area.^[62] Earlier Spanish missionary efforts in 1806 also advanced a half-day's march up the Merced River from the Central Valley, mapping terrain amid reconnaissance for potential mission sites, though these incursions remained limited and did not lead to permanent outposts.^[63] American exploration intensified after the 1848 California Gold Rush, with fur trappers like Joseph Reddeford Walker potentially viewing Yosemite Valley from afar during his 1833 Sierra Nevada crossing, though he did not descend into it.^[64] The first confirmed entry by European Americans into Yosemite Valley occurred on March 27, 1851, when the Mariposa Battalion, a volunteer militia led by James D. Savage, pursued Ahwahneechee Indians up the river's South Fork amid escalating conflicts following Native raids on mining settlements.^[65] Savage, who had established trading posts along the Merced River as early as 1849—including at the mouth of Piney Creek and the South Fork—facilitated these contacts, which displaced indigenous populations and opened the upper watershed to further incursion.^[56] Settlement accelerated in the 1850s, driven by placer mining along the river's lower reaches and tributaries, with towns like Snelling and Merced Falls emerging as hubs for both white prospectors and displaced Native groups; by 1851, approximately 695 Indians resided near Merced Falls amid mixed communities.^[66] Erastus Kelsey settled near Merced Falls in 1853, securing one of the county's earliest water rights for mining and ranching, exemplifying the riparian claims that underpinned expansion.^[67] Toll roads, such as the 1856 route built by Milton and Houston Mann up the South Fork Merced, connected these sites to Yosemite Valley, boosting access for loggers and early tourists. By the late 19th century, railroads extended along the Merced Canyon, supporting mining, timber extraction, and tourism while enabling agricultural colonization in the Central Valley floodplain.^[65] Modern settlement patterns solidified with irrigation development, as the Robla Canal Company formed in the mid-1880s to divert Merced waters for farming, leading to the Merced Irrigation District's establishment in 1919 and transforming the lower river into a agricultural corridor with colonies like Hilmar (1901) near the river's mouth.^[68] These efforts, rooted in Gold Rush-era squatting and water appropriation, shifted the region from transient mining camps to permanent agro-industrial communities, with the river serving as a vital axis for transport, hydropower precursors, and flood-prone valley reclamation.^[69]

Human Modifications and Engineering

Dams, Reservoirs, and Hydropower

The primary dams on the Merced River are operated by the Merced Irrigation District (MID) to support irrigation diversions, seasonal water storage, flood attenuation, and hydroelectric generation.^[70] These structures, concentrated in the lower river below Yosemite National Park, include the New Exchequer Dam, McSwain Dam, and Merced Falls Dam, which collectively form the core of the Merced River Hydroelectric Project (FERC Project No. 2179) and the separate Merced Falls Hydroelectric Project (FERC Project No. 2467).^[71] The projects generate power through run-of-river and storage operations, with combined installed capacity exceeding 100 megawatts, primarily from turbine facilities at the dams.^[72] ![Cascades Diversion Dam on the Merced River][float-right] The New Exchequer Dam, a 490-foot-high concrete-faced rock-fill structure completed in 1967, impounds Lake McClure, the river's largest reservoir with a storage capacity of 1,024,600 acre-feet.^[68] ^[17] Construction began in July 1964 and replaced the original Exchequer Dam (built in 1926 with 281,200 acre-feet capacity), expanding storage to manage seasonal flows from the 1,276-square-mile watershed for downstream irrigation and power production.^[68] ^[73] The associated Exchequer Powerhouse, located at the dam, has a generating capacity of 94.5 megawatts, utilizing water released through four turbines.^[74] Downstream, the McSwain Dam, an 80-foot-high embankment structure built as a regulating reservoir shortly after New Exchequer, forms Lake McSwain with 9,730 acre-feet of storage to stabilize outflows for power generation and irrigation releases.^[17] ^[75] It includes a powerhouse contributing to the project's total capacity of 103.5 megawatts across both facilities.^[71] Further downstream at river mile 55, the Merced Falls Dam maintains a small 65-acre impoundment with 678 acre-feet storage and generates 3.4 megawatts via a single development, focusing on diversion to canals alongside power output.^[76] Additional historical and minor structures include the Crocker-Huffman Diversion Dam, which facilitates irrigation extractions and features a fish ladder, though its operations have faced restrictions since the 1970s to protect salmonid migration.^[12] Upstream near Yosemite Valley, small diversion dams like the Cascades Diversion Dam—used for early 20th-century water supply and minor hydro—were removed in 2004 to restore natural river processes and habitat connectivity, with no major storage reservoirs present in the upper watershed.^[77] These facilities have enabled MID to produce an average of over 400 gigawatt-hours annually, though outputs vary with precipitation and demand.^[78]

Channelization, Flood Control, and Infrastructure

In Yosemite Valley, portions of the Merced River and its tributaries were channelized during the 20th century to mitigate flooding, stabilize banks, and protect infrastructure such as roads and buildings from erosion and high flows.^[5] These modifications involved straightening meanders, installing revetments, and constructing channel-spanning bridges, which reduced channel roughness, promoted incision, and decoupled the river from its floodplain, limiting natural overbank flooding and sediment deposition essential for meadow health.^[79] Following major floods, including the 1997 event that damaged facilities and highlighted vulnerabilities, the National Park Service initiated restoration projects to reverse channelization effects, removing artificial constraints like excess riprap and realigning segments to restore dynamic processes such as meander migration and habitat connectivity.^[80] By 2020, these efforts had focused on a 5-km reach from Happy Isles to Sentinel Bridge, emphasizing scientific design to enhance geomorphic complexity without compromising flood safety.^[81] Downstream in the Central Valley, channelization and flood control emphasize maintenance over extensive structural alteration of the mainstem Merced River, with periodic vegetation removal and sediment clearing to sustain conveyance capacity and prevent capacity exceedance during high flows. Merced County maintains channels and levees primarily on tributaries like Black Rascal Creek, Burns Creek, and Mariposa Creek, as part of the 1957 Merced County Streams Group Flood Control Project integrated into the Sacramento-San Joaquin comprehensive plan, which improved downstream channels to handle floodwaters.^[82] Limited levees exist along the Merced mainstem, where flood stages are influenced by backwater from the San Joaquin River, prompting reliance on bypass systems like the Mariposa and Eastside Bypasses for overflow diversion during extreme events.^[83] Recent floodplain management experiments, such as temporary levee breaches on adjacent reaches, have demonstrated potential for controlled inundation to recharge groundwater and reduce peak flows, though permanent levee removals remain selective to balance flood risk.^[84] Key infrastructure includes over 10 bridges spanning the Merced in Yosemite Valley alone, such as the historic Pohono, Sentinel, and Swinging bridges, which, while enabling access, have altered local hydraulics by constraining flow and exacerbating incision in some reaches. ^[85] Downstream crossings, like the 1912 Shaffer Bridge (a steel Pratt through-truss structure) and ongoing replacements such as the Oakdale Road bridge, prioritize seismic resilience, hydraulic capacity, and roadway alignment to accommodate traffic while minimizing scour risks.^[86] ^[87] Irrigation-related infrastructure features diversion points and canal systems, exemplified by the Livingston Canal split structure, which manages water allocation through gates and spillways to prevent erosion and ensure efficient off-take during varying river stages.^[88]

Water Management and Rights

Allocation, Uses, and Economic Role

The Merced River's water is primarily allocated through a combination of riparian rights, pre-1914 appropriative claims, and post-1914 permits administered by the California State Water Resources Control Board, with the Merced Irrigation District (MID) holding significant senior rights dating to its formation in 1919.^[89] ^[90] MID diverts water via infrastructure including the New Exchequer Dam (completed 1926) and McSwain Dam (1960), storing up to approximately 1 million acre-feet combined in reservoirs for seasonal release.^[70] Annual allocations prioritize irrigation demands, with MID supplying an average of 300,000 acre-feet to irrigate about 115,000 acres across its 164,000-acre service area serving over 2,200 agricultural users.^[91] ^[92] Diversions occur mainly during non-winter months, but undocumented or unreported extractions by junior rights holders have contributed to critically low flows, including complete dewatering of the lower river for periods in 2014, 2015, 2016, 2021, and extensively in 2022.^[93] ^[43] Primary uses of Merced River water center on agriculture, which consumes the majority via MID's canal system for crop irrigation in Merced County, supporting high-value outputs like almonds, dairy, and tomatoes.^[94] Hydropower generation from the federally licensed Merced River Hydroelectric Project (FERC No. 2179) provides secondary benefits, producing electricity sold to Central California utilities while integrating with irrigation scheduling for peak efficiency.^[95] Other allocations include municipal supply for roughly 150,000 residents, groundwater recharge to sustain aquifers, and limited industrial needs, with flood control releases managed cooperatively during high flows.^[96] ^[95] Economically, the river underpins Merced County's agriculture-dependent economy, which generates billions in annual output reliant on reliable surface water; a 20% reduction in availability could eliminate up to $672 million in local economic activity and $167 million in labor income, per modeling by MID economists.^[96] The hydroelectric facilities contribute renewable energy revenues that offset irrigation costs and support district operations, while irrigation enables farming on marginal soils, amplifying productivity through efficient water application—Merced County agriculture alone accounts for a substantial share of California's Central Valley output, where irrigated lands produce 40% of U.S. fruits, nuts, and vegetables.^[94] ^[97] Drought-induced curtailments, as in 2020–2022, have forced fallowing and crop shifts, underscoring the river's causal role in regional employment (thousands of jobs tied to irrigated farming) and GDP contributions exceeding $2 billion pre-drought impacts.^[98]

Disputes, Regulations, and Policy Debates

The Merced River's lower reaches are subject to federal protections under the Wild and Scenic Rivers Act of 1968, with approximately 71 miles designated as wild and scenic starting in 1987, primarily within Yosemite National Park and extending downstream, mandating the preservation of free-flowing conditions and outstandingly remarkable values such as scenic, recreational, and ecological attributes.^[99] These designations prohibit new dams or major diversions that impair river integrity, influencing operations at upstream facilities like the New Exchequer Dam, which provides flood control, hydropower, and irrigation but must adhere to instream flow minima for fisheries and habitat.^[12] State regulations, enforced by the California State Water Resources Control Board, include license conditions for the Merced Irrigation District (MID) requiring minimum flows—such as 100 cubic feet per second during certain periods—to support salmonid migration and riparian ecosystems, though enforcement has faced criticism for inconsistencies.^[100]^[89] Significant disputes have arisen over flow depletions, exemplified by the river running dry near Snelling in July 2023 due to MID's diversions exceeding monitored levels, prompting investigations into regulatory oversight failures and calls for permanent minimum flow mandates below Yosemite to prevent habitat desiccation for species like Chinook salmon.^[93]^[100] In 2023, federal and state agencies, including the U.S. Fish and Wildlife Service and National Marine Fisheries Service, intervened in litigation against MID to restore a defunct fish ladder at the Crocker-Huffman Dam, arguing its absence blocks upstream salmon passage critical for recovery under the Endangered Species Act, with courts remanding the case for trial.^[101]^[102] Federal Energy Regulatory Commission relicensing for the Merced River Hydroelectric Project (FERC P-2179) has involved study disputes since 2009, where environmental groups contested MID's assessments of flow impacts on downstream ecology versus hydropower generation. Policy debates center on balancing agricultural demands—MID supplies over 1 million acre-feet annually to Central Valley farms—with ecological imperatives, as evidenced by repeated congressional attempts from 2011 to 2014 by Representatives Jeff Denham and Tom McClintock to delist 0.6 miles of the lower Merced from wild and scenic status, enabling a 7-foot raise in Lake McClure's surface to expand storage by 12,000 acre-feet for drought resilience, opposed by conservationists as undermining the Act's free-flow prohibition.^[103]^[104] These efforts failed amid concerns over precedent for eroding protections, highlighting tensions between economic water security in arid regions and causal linkages between reduced flows and biodiversity loss, with no new capacity approved but interim operating limits revised in Yosemite's 2013 Merced River Plan to sustain aquatic habitat amid visitation pressures.^[99]^[105] Ongoing National Park Service management debates emphasize adaptive flow regimes to mitigate climate-driven variability, prioritizing empirical monitoring over fixed allocations to preserve geomorphic processes.^[99]

Recreation, Tourism, and Conservation

Recreational Activities and Access

The Merced River supports diverse recreational activities, including rafting, fishing, hiking, swimming, and camping, concentrated in Yosemite National Park and adjacent public lands managed by the Bureau of Land Management (BLM) and U.S. Forest Service.^[106]^[107] In Yosemite Valley, the river's calm sections from Stoneman Bridge to El Capitan Bridge permit daily boating and inflatable rafting when the gage height at Pohono Bridge exceeds 3.5 feet, typically from late May to early August depending on snowmelt.^[108] Raft rentals, accommodating 2 to 4 people for 3-mile floats, operate mid-July to early August via concessionaires, with mandatory personal flotation devices for all participants and restrictions barring children under 50 pounds.^[109] Fishing targets rainbow trout and other species, requiring a California fishing license for those 16 and older, plus adherence to Wild and Scenic River designations limiting harvest to fish over 12 inches using artificial lures or flies only.^[110]^[8] Within Yosemite, the season runs from the last Saturday in April to November 15, with catch-and-release enforced from Happy Isles to Foresta Bridge for rainbow trout and a 5-fish daily limit for others.^[111]^[112] Hiking trails, such as the Merced River Trail from Railroad Flat Campground downstream, provide year-round access for anglers and day-users, though steep terrain along Highway 140 limits some entry points.^[113]^[114] Access occurs primarily via California State Route 140, paralleling the river from El Portal to Yosemite Valley, with designated pullouts, bridges like Swinging Bridge in Wawona for South Fork entry, and the Briceburg Visitor Center for BLM-managed stretches below the park.^[107]^[114] Whitewater rafting and kayaking thrive on undammed sections during April to June high flows, with launches at Redbud Boat Launch to Briceburg avoiding Class IV+ rapids upstream.^[115]^[116] Swimming and picnicking occur at sandy beaches like McCabe Flat Campground, subject to variable flows and park advisories against non-swimmers entering swift currents.^[110] Camping facilities, including BLM sites reachable via suspension bridges past Briceburg, support extended stays with amenities for these pursuits.^[107] Regulations emphasize safety, prohibiting tubing in hazardous areas and requiring permits for commercial outfitters.^[106]

Protected Status and Restoration Initiatives

Significant portions of the Merced River, particularly its upper reaches, are safeguarded within Yosemite National Park, established by Congress on October 1, 1890, encompassing about 71 miles of river corridor where park boundaries protect the free-flowing nature, water quality, and ecological integrity from development and incompatible uses.^[2] In 1987, Congress designated 122 miles of the Merced River—spanning from its headwaters in the Sierra Nevada through Yosemite to below Lake McClure—as a National Wild and Scenic River under Public Law 100-149, classifying upstream segments as "wild" (minimal human alteration), mid-reaches as "scenic" (some access but natural character preserved), and lower portions as "recreational" (with existing development but protected values).^[117] This designation, administered jointly by the National Park Service (NPS), U.S. Forest Service (USFS), and Bureau of Land Management (BLM)—with BLM overseeing 12 miles of rapids-focused corridor—prohibits new dams or diversions that impair outstanding scenic, recreational, geologic, fish, wildlife, historic, and cultural values, while requiring comprehensive management plans to guide land use.^[7] The NPS's Merced River Plan, finalized in September 2021 after environmental impact analysis, implements Wild and Scenic requirements by limiting user capacity in Yosemite Valley (e.g., capping campsites and lodging units to prevent overcrowding impacts on riverbanks), enforcing riparian setbacks for infrastructure, and monitoring water quality to sustain native species like Yosemite toad and Little Kern golden trout.^[118] These measures address legacy effects from 20th-century park development, such as channelized banks and flood control structures, prioritizing natural floodplain dynamics over engineered stability.^[119] Restoration initiatives have focused on reversing anthropogenic alterations, particularly after the January 1997 flood that scoured Yosemite Valley and exposed entrenched channels. NPS-led projects since 1998 include reconfiguring 2.5 miles of river in the Valley by removing riprap, placing large woody debris for habitat complexity, revegetating with native willows and sedges on 50+ acres, and fencing to exclude grazing and human trampling, thereby restoring meandering patterns, overbank flooding, and riparian ecosystems that support biodiversity.^[80] In the lower Merced, the Merced Irrigation District's Instream and Off-Channel Habitat Restoration Project, completed in phases through 2020, rehabilitated 0.5 miles of mainstem channel and 7 acres of riparian zone for Chinook salmon and steelhead, incorporating gravel augmentation and side-channel creation to mimic pre-mining conditions altered by 19th-century hydraulic operations.^[120] Further efforts under the NOAA-supported Merced River Corridor Restoration Plan (Phase IV, initiated 2010s) target dredger tailings sites, planning sediment removal and native planting across 100+ acres to reconnect floodplains and boost salmonid spawning success, with monitoring showing increased juvenile outmigration post-intervention.^[121] These initiatives, funded partly by federal Sport Fish Restoration Act grants, emphasize empirical geomorphic modeling and pre/post metrics like sediment transport rates, rather than unsubstantiated ecological assumptions.^[122]

References

[1]
Merced River | Rivers.gov
From its source on the south side of Mount Lyell at 13,114 feet, through a glacially carved canyon within Yosemite National Park, the river flows downstream ...Missing: length | Show results with:length
[2]
Merced River Restoration - Yosemite National Park (U.S. National ...
Jul 2, 2024 · The Merced River was added to the National Wild and Scenic Rivers System in 1987 in acknowledgement of the river's (1) free-flowing condition, ( ...Missing: significance | Show results with:significance
[3]
[PDF] Selected water-quality data from the Merced River, California ...
The Merced River originates on the western slope of the Sierra Nevada and flows through Yosemite National Park. The river drains 1,276 square miles.Missing: elevation | Show results with:elevation
[4]
Hydrology and Watersheds - Yosemite National Park (U.S. National ...
The upper Merced River descends from its headwaters through a glacially carved canyon at a gradient of about 8,000 feet over 24 miles. The average daily ...Missing: mouth | Show results with:mouth
[5]
Merced River Restoration - Meadows and Wetlands
Nov 5, 2020 · Informal trails have many harmful ripple effects in natural systems. Fragmentation has further effects on meadow hydrology, habitat quality, and ...Missing: issues | Show results with:issues
[6]
[PDF] Merced River Watershed Flood-MAR Reconnaissance Study
Nov 1, 2023 · The Merced River is a highly channelized river system and increased flow results in deeper and higher velocity flows, contrary to the.
[7]
California: Merced Wild and Scenic River | Bureau of Land ...
From Yosemite National Park, the Merced River tumbles through glacially carved canyons, rugged mountains, and foothills on its way to the San Joaquin Valley ...
[8]
Merced River - Main Fork | Discover Yosemite National Park
The Merced River in Mariposa County is an excellent place for rafting, camping, gold-panning and fishing near Yosemite National Park.Missing: significance | Show results with:significance
[9]
How Long Is the Merced River From Start to End? - A-Z Animals
Dec 5, 2023 · The Merced River is 145 miles long from the source to the mouth. That's about half as long as the Grand Canyon, which is 277 miles long.
[10]
Overview — Upper Merced River Watershed Council
The South Fork - the Merced River's largest tributary - flows from its source in Yosemite National Park and the community of Wawona, to the confluence with the ...Missing: major | Show results with:major
[11]
USGS 11272500 MERCED R NR STEVINSON CA
Discharge, cubic feet per second, 1940-10-01, 2010-09-29, 23008. Monthly Statistics. Discharge, cubic feet per second, 1940-10, 2010-09. Annual Statistics.Missing: average | Show results with:average
[12]
[PDF] Merced River Watershed Profile - Mariposa County
The gorge has remained an incised, V-shaped feature because the most recent glacial events did not extend down the Merced River beyond Yosemite Valley.Missing: length | Show results with:length
[13]
[PDF] Merced Irrigation District Hydrologic and Hydraulic Optimization ...
Figure 17: Average Daily Flow for Merced River at Shaffer Bridge ... is a discrepancy between the flow rates recorded at the same location by USGS and the CDEC.
[14]
Water-Year Summary for Site USGS 11264500
EXTREMES FOR PERIOD OF RECORD - Maximum discharge, 10,100 ft³/s, Jan. 2, 1997, gage height, 13.27 ft, from rating curve extended above 4,000 ft³/s, on basis of ...Missing: average | Show results with:average
[15]
Merced R a Happy Isles Bridge NR Yosemite CA - USGS-11264500
Discover water data collected at monitoring location USGS-11264500, located in California and find additional nearby monitoring locations.
[16]
[PDF] Water-quality assessment of the merced river, california
The climate in the basin varies with elevation. High elevation areas are ... of the Merced River downstream from Merced Falls Dam, Merced County,.
[17]
[PDF] Merced River Watershed Flood-MAR Reconnaissance Study
Cumulatively, the 48-year historic amount of floodwater available for recharge was between 700–2,200 taf (or 15–46 taf/year average annual recharge). Results of ...
[18]
[PDF] Precipitation-Runoff Processes in the Merced River Basin, Central ...
Oct 30, 2024 · Flow rate cubic foot per second (ft3/s). 0.02832 cubic meter per ... holding capacity of the gravity and preferential-flow reservoirs;.
[19]
Geology - Yosemite National Park (U.S. National Park Service)
Nov 22, 2024 · The Sierra Nevada is mainly composed of granite, a salt-and-pepper appearing rock composed primarily of quartz, plagioclase, potassium feldspar, ...
[20]
The geology, geomorphology, and soils of the San Joaquin Valley in ...
Aug 3, 2009 · The Merced River crosses the Pleistocene formations in a flat-floored valley bordered by bluffs 40 to 60 feet high. The valley is underlain ...
[21]
Geologic history of the Yosemite Valley - USGS.gov
The Yosemite Valley's origin is from both glacial and stream erosion. The preglacial depth was about 2,400 feet from El Capitan and 2,000 feet from Glacier ...
[22]
[PDF] A Brief Story of the Geology of Yosemite Valley (1943) by ME Beatty
Yosemite Valley was occupied by a huge trunk glacier, one branch coming down the Merced River canyon over what is now Vernal and Nevada Falls, and the other ...<|separator|>
[23]
Geology Tour - Around the River Bend (U.S. National Park Service)
Oct 20, 2023 · Since glaciers retreated from Yosemite Valley about 16,000 years ago, the Merced River has been moving back and forth in a S-shaped pattern ...Missing: formation | Show results with:formation
[24]
Geological and Hydrologic Values
Oct 31, 2024 · The Merced River, from Happy Isles to the west end of Yosemite Valley, provides an outstanding example of a rare, mid-elevation alluvial river.
[25]
Is drainage reorganization a plausible explanation for late Cenozoic ...
Apr 3, 2025 · The evidence supports drainage reorganization as a plausible explanation for the preglacial late Cenozoic deepening of Yosemite Valley and ...
[26]
geographic sketch of the yosemite region and the sierra nevada
Nov 28, 2006 · Its central meadows have an altitude of over 8,500 feet; they lie 1,500 feet above Merced Lake and 4,500 feet above the Yosemite Valley.
[27]
Biological Values - Upper Merced River Watershed Council
Nov 1, 2024 · Endemic only to the Merced River canyon, the Limestone Salamander is perhaps the rarest and most unique species along the watershed. There are ...
[28]
Merced Clarkia - California Department of Fish and Wildlife
Merced clarkia is a California endangered plant species, which means that killing or possessing the plant is prohibited by the California Natural Diversity ...
[29]
Fish - Yosemite National Park (U.S. National Park Service)
Nov 19, 2024 · Native fish—including California roach, Sacramento pikeminnow, hardhead, and riffle sculpin—inhabit the lower reaches of the Merced River up to ...
[30]
Merced River Steelhead / Rainbow Trout
At that time, it was concluded that the Central Valley steelhead distinct population segment (DPS) was in danger of extinction due to widespread habitat ...Missing: ecosystem | Show results with:ecosystem<|control11|><|separator|>
[31]
Animals - Yosemite National Park (U.S. National Park Service)
Jan 19, 2017 · Yosemite National Park supports more than 400 species of vertebrates including fish, amphibians, reptiles, birds, and mammals.Birds · Mammals · Reptiles · Amphibians
[32]
Mammals - Yosemite National Park (U.S. National Park Service)
Feb 13, 2017 · Yosemite National Park's approximately 90 mammal species, and their behaviors, are truly fascinating for park visitors to observe safely and responsibly.
[33]
Birds - Yosemite National Park (U.S. National Park Service)
Sep 5, 2023 · An astounding 262 species of birds have been documented in Yosemite, including 165 resident and migratory species. Of note, 46 species have been ...
[34]
Merced River Restoration - Technical Findings - National Park Service
Jan 7, 2025 · The river emerges from the primary influence of coarse-grained glacial-age sedimentary deposits in the reach between Clarks Bridge and Sugar ...
[35]
[PDF] PROJECT TERM: 06/01/06-06/30/13 AMOUNT FUNDED
The ecological parts of the study concerned three issues of general significance for river restoration: the aquatic food web and its relationship to fish growth ...
[36]
[PDF] Endangered Species Act Section 7(a)(2) Biological Opinion and ...
May 7, 2024 · Identify and implement floodplain and side channel projects to improve river function and increase habitat diversity in the Merced River. • ...
[37]
How Does Restored Habitat For Chinook Salmon ( Oncorhynchus ...
Aug 6, 2025 · However, compared with other streams in the region, the Merced has minimal riparian cover, fewer undercut banks, less woody debris and higher ...
[38]
Merced River Conditions in 2022 | California State Water Resources ...
Dec 13, 2024 · The Merced River experienced very low flow and dry conditions during the summer and early fall of 2022. The State Water Board received letters ...
[39]
San Joaquin River Restoration | NOAA Fisheries
Aug 13, 2025 · Spring-run Chinook salmon need cool, clean water to survive the hot summer temperatures, because most of the cold spring snowmelt is now ...San Joaquin River Restoration... · How did the San Joaquin...
[40]
Drought Stressor Monitoring Case Study: Lower Merced River ...
The Merced River flows from Southern Yosemite National Park 135 miles downstream to the San Joaquin River (SJR) confluence. It is the southern-most SJR ...Missing: length | Show results with:length
[41]
[PDF] Merced River Robinson Reach Maintenance Project — January 2022
Feb 22, 2022 · habitat and river dynamics (California Wildlife Conservation Board 2002). ... ecological functions of the Merced River degraded by mining ...
[42]
Gallo fined for dumping wastewater in Merced River
Feb 7, 2023 · The board investigated the discharge and found that the water had “elevated levels of potassium, organic matter and salinity” that could ...
[43]
The Merced River Ran Dry… And Nobody Knew About It
Mar 16, 2025 · Minimum flows that protect fish and wildlife, the ecosystems on which they rely, · Salmon reproductive habitat enhancement (addition and ...Missing: threats | Show results with:threats
[44]
10.5: Case Study - Yosemite National Park - Geosciences LibreTexts
Dec 21, 2024 · Merced Glacier flowed out of Yosemite Valley and into the Merced River Gorge. Lee Vining Glacier carved Lee Vining Canyon and emptied into Lake ...
[45]
How old is Yosemite Valley? - University of California
Oct 20, 2022 · Did the valley only begin to form after the Sierra tilted toward the west some 5 million years ago, or was it mostly due to glaciers that formed ...
[46]
glacial history of the yosemite valley - National Park Service
Nov 28, 2006 · In preglacial time Tenaya Creek, accelerated by the successive uplifts of the Sierra Nevada, deepened the canyon almost as rapidly as the Merced ...
[47]
Rangewide glaciation in the Sierra Nevada, California | Geosphere
Dec 1, 2013 · In the Merced and San Joaquin River drainages, deposits older than Tahoe/Tioga have been correlated with the Sherwin glaciation on the east ...
[48]
[PDF] Late Cenozoic Stratigraphic Units, Northeastern San Joaquin Valley ...
Kern River Formation, however, were deposited by meandering ... Schematic geologic section across the Merced River near Snelling, Merced County, showing relation ...
[49]
Their Lifeways - Yosemite National Park (U.S. National Park Service)
Nov 21, 2022 · Indian people have lived in Yosemite for nearly 4,000 years. Miwok legends tell of the creation of people here, and of events that took place ...
[50]
Archeology - Yosemite National Park (U.S. National Park Service)
Sep 9, 2025 · Archeologists have uncovered material evidence that suggests that people were hunting in the Yosemite region nearly 10,000 years ago.
[51]
[PDF] CULTURAL AND HISTORIC RESOURCES - Mariposa County
Mar 11, 2005 · In addition, archaeological sites in the vicinity of El Portal indicate that the Merced River canyon may have been inhabited as early as 9,500 ...Missing: indigenous | Show results with:indigenous
[52]
River Essays - Merced - Basia Irland
Specific goals of the Merced River Plan include; “Protect and Enhance Ecological and Natural Resource River Values, Provide Opportunities for Direct Connection ...Missing: significance | Show results with:significance<|separator|>
[53]
[DOC] Presenter Notes
The Merced River is known to the Native people of the Valley as the Wa-kal-la, which simply means “the river”. Though there were many tribes and villages ...
[54]
[PDF] Indigenous Fisheries of the Southern Sierra Miwuk - Squarespace
The evidence for the salmon runs on the five rivers of this study; the Stanislaus River, the Toulumne River, the Merced River, the. Chowchilla River, and the ...<|separator|>
[55]
[PDF] Indigenous Fisheries of the Southern Sierra Miwuk California ...
“At the time the Merced River was free of obstructions and the steelhead and salmon ascended the Merced. River to Wawona and into Yosemite Valley as far as the ...
[56]
Yosemite: the Park and its Resources (1987) by Linda W. Greene
... Miwoks moved down to the milder climate of the Merced River canyon; and seasonal hunting, fishing, and gathering camps.7 Occupational patterns in those ...<|control11|><|separator|>
[57]
[PDF] Miwok
commonly settled along the rivers in the valleys for fish and water and would travel up into the hills and mountains to hunt (The valleys, hills, and rivers ...
[58]
[PDF] NATIVE AMERICAN FIRE PATTERNS IN YOSEMITE VALLEY
Native American fire regimes in Yosemite Valley consisted of spatially small, low-intensity surface fires in all areas regardless of differences in distance ...<|separator|>
[59]
"The Miwok," The North American Indian by Edward S. Curtis (1924)
Obsidian points for arrows and fish-spears were purchased from the Mono. [1 This may not have been true outside the southern and central districts.] The ...
[60]
did you know that native americans were inhabitants of yosemite ...
Nov 15, 2024 · The natives of the vicinity, the Koyeti tribe towards the west and the Yandanchi tribe toward the east, were branches of the Yokuts Indians ...The Yokayo band of Pomo people who inhabited the Russian River ...Yokuts indigenous people of Merced, California - FacebookMore results from www.facebook.comMissing: pre- contact
[61]
Yosemite Indians - National Park Service
Sep 25, 2025 · This is a brief introduction to the Southern Sierra Miwok life, history, and language, providing further information about the Indian ...
[62]
On Hold History Narratives | Mariposa County, CA - Official Website
In the fall of 1806 Spanish explorer Lieutenant Gabriel Moraga led a company of men from the San Joaquin River toward some distant foothills to the east.
[63]
Early History of Yosemite Valley
Dec 9, 2011 · On the 20th of May, 1852, a party of eight prospectors started from Coarse Gold Gulch on a trip to the upper waters of the Merced River. They ...
[64]
The Geologic Story of Yosemite National Park
... Rivers, a route later followed by the western part of the Tioga Road. Walker and his men were probably the first of European descent to view Yosemite Valley ...
[65]
Explorers and Recorders - Yosemite National Park (U.S. National ...
Aug 26, 2021 · After the Mariposa Battalion became the first known European Americans to enter Yosemite Valley in 1851, doors opened for intrepid tourists ...
[66]
Merced Falls and Snelling | Settlement of Merced County (MOBILE)
There were about 695 Indians in and near the Merced Falls Reservation in 1851. Merced Falls was a busy river town with both Indian and white settlers. Because ...
[67]
Early water rights traced back to Merced Falls, settlers
Jul 29, 2019 · Erastus Kelsey (seen at upper right in photo), who settled near Merced Falls in 1853, obtained one of the first water rights in Merced County.
[68]
History of the Yosemite area - Wikipedia
Exploration by European Americans. edit ... Milton and Houston Mann opened a toll road to Yosemite Valley in 1856, up the South Fork of the Merced River.
[69]
History of the District - Merced Irrigation District
The Merced Irrigation History of the District can trace its roots back to the mid 1800s when the Robla Canal Company was formed.
[70]
Following the Water: A History of Merced County Irrigation
From the beginning of human settlement to becoming the nation's most productive farm belt, Merced County like the rest of the Central Valley has battled over ...<|separator|>
[71]
About Merced Irrigation District in Merced County CA
Merced Irrigation District owns, operates and maintains the New Exchequer and McSwain dams, reservoirs, and hydroelectric facilities.
[72]
West Coast Federal Energy Regulatory Commission (FERC ...
Oct 22, 2024 · The Merced River Hydroelectric Project (P-2179) (owned by Merced Irrigation District (MID)) is being relicensed concurrently with the Merced Falls ...
[73]
Hydro Energy - Merced Irrigation District
The Merced River Hydroelectric Project is comprised of two hydroelectric powerhouses at New Exchequer Dam and McSwain Dam.Missing: reservoirs California
[74]
[PDF] Agricultural Water Management Plan - Merced Irrigation District
major facilities which included Old Exchequer Dam on the Merced River with a storage capacity of. 281,200 acre-feet (AF). After the 1920's, MID's next major ...
[75]
Power plant profile: Exchequer, US
Oct 21, 2024 · Exchequer is a 94.5MW hydro power project. It is located on Merced river/basin in California, the US. According to GlobalData, who tracks ...Missing: Dam | Show results with:Dam<|separator|>
[76]
[PDF] Federal Register/Vol. 77, No. 52/Friday, March 16, 2012/Notices
Mar 16, 2012 · McSwain Development—(1) McSwain. Dam—located 6.3 River Miles downstream from New Exchequer dam,. McSwain is an 80 feet-high embankment structure ...
[77]
Merced Falls Hydroelectric Project | California State Water ...
Aug 4, 2025 · The 3.4 megawatt Project consists of one power generating development with a 65 surface acre impoundment with an approximate storage capacity of 678 acre-feet ...Missing: history | Show results with:history
[78]
Cascades Diversion Dam Removal - Yosemite - National Park Service
Jun 1, 2023 · Cascades Diversion Dam, once located on the Merced River just west of Yosemite Valley, was removed in 2004 followed by re-vegetation and monitoring of the ...
[79]
[PDF] Merced River and Merced Falls DEIS - GovInfo
The Merced River Project is located on the main stem of the Merced River in Mariposa County, about 23 miles northeast of the city of Merced, California.
[80]
Opportunities and challenges for restoration of the Merced River ...
Sep 2, 2020 · Riparian-zone disturbance by visitor use has damaged riparian vegetation and soils, inducing channel widening. Revetments and channel ...Missing: plants | Show results with:plants
[81]
Merced River Restoration - Projects - National Park Service
Jul 2, 2024 · The Merced River Plan (MRP) identifies both passive and active ecological restoration actions to restore these natural and cultural processes.Missing: issues | Show results with:issues
[82]
[PDF] Restoration of the Merced River through Yosemite Valley, Yosemite ...
Oct 14, 2020 · 1 BACKGROUND. 1.1 Purpose. The purpose of this project is to provide scientific and engineering design support to Merced River.
[83]
[PDF] 13 hydrology and water resources - web2 | Merced County
Major water supply and diversion dams, reservoirs, and hydroelectric power projects regulate and control flow along the San Joaquin River, the Merced River, ...
[84]
[PDF] Report (pdf)
Reduction in peak discharge is dependent on river stage, prior river flows, magnitude of ... Figure 52..- Effect of Dry Creek flow on discharge of the Merced ...<|separator|>
[85]
Floodplain Management Can Increase Groundwater Supply
Apr 9, 2015 · The researchers removed levees adjacent to the river that were in risk of being overtopped, but contained flood waters across an 500-acre ...
[86]
Historic bridges of Yosemite Valley under siege | The Seattle Times
Jul 7, 2012 · Four other Yosemite Valley bridges cross the Merced River, but only these three are built into the river, said park spokesman Scott Gediman.
[87]
Merced River Bridge - Digital Collections
Shaffer Bridge (39C0013) was constructed in 1912 and is a steel Pratt through-truss bridge with three spans measuring 152 feet long each. The bridge is ...
[88]
Oakdale Bridge Project at the Merced River - CEQAnet - CA.gov
The project proposes to construct a new bridge for Oakdale Road over the Merced River. The project would construct the bridge approximately 50 meters north ...Missing: infrastructure canals
[89]
Livingston Canal Split at Merced River - HigherGov
Oct 15, 2025 · The project consists of demolition of existing spill structure, salvage of existing canal gates, construction of new spill structure, ...
[90]
Merced River Conditions in 2022 | California State Water Resources ...
Sep 26, 2024 · The Merced River is a tributary of the San Joaquin River and is an important source of water for many Californians living in the San Joaquin ...Missing: major | Show results with:major<|separator|>
[91]
MID Water - California Water - Merced Irrigation District Water
The Merced Irrigation District was formed on December 8, 1919. It is comprised of a service area spanning more than 164,000 gross acres.
[92]
Merced Irrigation District - Water & Power Energy
Merced Irrigation District provides an average of 300,000 acre feet of water each year to approximately 2,200 growers. At 325,000 gallons per acre foot, that's ...Settle the Merced River · Lower Merced River Coalition · History of the District
[93]
[PDF] Merced Irrigation District - State Water Resources Control Board
Total Acres In-District: 154,000. Acres Irrigated In-District: 115,000. SOI/Commitment Acreage: 60,000. Water Users: 2,223. Total Miles of Canals:.<|separator|>
[94]
California's Merced River dried up below Yosemite. Now we know why
Dec 20, 2024 · State water data reviewed by the Chronicle show that the river had no flow for parts of 2021, 2016 and 2014. Additionally, in 2015, the river ...Missing: statistics | Show results with:statistics<|control11|><|separator|>
[95]
[PDF] Economic Impacts of Reduced Water Availability to Merced Irrigation ...
The balance of this report is presented in four chapters: ▫ Study Area – Provides demographic and economic background information about Merced. County. ▫ Merced ...
[96]
Merced River Hydroelectric Project
MID primarily operates the Project for agricultural irrigation, however, other beneficial uses include: hydropower, groundwater recharge, municipal and ...
[97]
Settle the Merced River - Merced Irrigation District Water & Power
Drinking water quality for 150,000 of our residents; Up to $672 million in lost local economic activity; Up to $167 million in local labor income. After years ...
[98]
Priorities for California's Water - Public Policy Institute of California
On average, California's residents and non-farm businesses use about 10 percent of the state's water supplies, and irrigated agriculture uses about 40 percent.<|separator|>
[99]
[PDF] Economic Impacts of the 2020–22 Drought on California Agriculture
Nov 22, 2022 · California, additional cooperative solutions to reduce irrigation water use may be on the horizon to address these longer-term challenges in ...
[100]
[PDF] Record of Decision for Merced Wild and Scenic River Revised ...
The Revised Merced River Plan/SEIS clarifies issues related to interim limits in Alternative 2. The document now states that the interim limits would last for ...Missing: disputes debates
[101]
How A Lack of Regulatory Oversight Dried Up the Merced River
Jan 22, 2024 · Flows at the confluence of the Merced River are essential for an overall functioning ecosystem and riparian habitat in this major watershed. In ...<|separator|>
[102]
State and federal agencies want fish ladder restored on Merced River
Feb 1, 2023 · Powerful state and federal agencies weigh in on lawsuit against Merced Irrigation District over defunct fish ladder.
[103]
Litigation - Water Audit California
Water Audit prevails in Merced River fish ladder appeal: back to trial court ... California Court Rules Against Kern River Water Diversions. Monday's ruling ...Missing: debates | Show results with:debates<|separator|>
[104]
Merced Threat | Friends of the River
A proposal to dangerously enlarge a dam and roll back Wild & Scenic protection. The Merced National Wild & Scenic River flows from glaciers at the crest of the ...Missing: ecosystem | Show results with:ecosystem
[105]
California Should Defend National Wild & Scenic Rivers
Mar 18, 2025 · For example, the GOP-led House of Representatives voted three times from 2011 to 2014 to remove a portion of the Merced River from the national ...
[106]
https://www.nps.gov/yose/planyourvisit/water.htm
[107]
Water Activities - Yosemite National Park (U.S. National Park Service)
Aug 31, 2023 · Boating and Rafting. Merced River. Rafting along the Merced River is popular during summer. You can rent a raft (typically in June and July, but ...
[108]
Merced River Recreation Management Area | California
The Merced River Trail continues downstream from the end of the Briceburg River Road and brings hikers or bikers to the North Fork of the Merced River and ...
[109]
Boating - Yosemite Valley - National Park Service
Jun 28, 2022 · The Merced River from Stoneman Bridge to El Capitan Bridge is open to boating and rafting each day when the gage height at Pohono Bridge is ...<|separator|>
[110]
Yosemite Rafting | Yosemite National Park
Make a splash rafting in Yosemite! Enjoy a 3-mile float on the Merced River, cool off and take in stunning views. Perfect for 2 to 4 people, mid-July to ...
[111]
Merced River Itinerary | 4 Days of Merced River Fishing & Hiking
The 4-day itinerary includes whitewater rafting, hiking, fishing, and gold panning, with activities like swimming, picnics, and exploring local history.
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Merced River Fishing Yosemite National Park
On the Merced River from Happy Isles to the Foresta Bridge in El Portal it is catch and release for all rainbow trout. For other trout the limit is 5 per day.
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Upper Merced River – home to trout and bass - - Fly Fishing the Sierra
Park Regulations. Within the Park, the season for the Merced is last Saturday in April to November 15th with a limit of 5 Trout and no gear restrictions.Missing: hiking | Show results with:hiking
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Merced River Trail, California - 216 Reviews, Map - AllTrails
Rating 4.5 (216) Merced River Trail is considered a moderate hike that covers 5.6 mi, with an elevation gain of 314 ft. It takes about 2–2.5 hr to complete. Moderate trails ...
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DIY Guide to Fly Fishing Merced River in California
May 9, 2020 · FREE guide and Merced River fishing map. Get directions to the best fishing spots, stream flows, fishing reports and fly fishing tips.
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Merced - 5) Redbud to Briceburg - American Whitewater
Briceburg is where highway 140 comes down to the river from Mariposa. There is a river access area with a toilet. An old stone building is now a museum run by ...
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Merced River Rafting Map and Guide - GoRafting.com
The most popular section of the Merced river runs from Redbud Boat Launch to Railroad Flat. This section avoids the stout CIass IV+/V whitewater above Redbud, ...
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[PDF] Merced Wild and Scenic River
Mar 31, 2014 · Congress designated 122 miles of the Merced River as a Wild and Scenic River in 1987 (Public Law 100-149). The designation applies to the ...
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Merced River Plan - National Park Service
Sep 16, 2025 · The Final Merced River Plan/EIS protects the Merced River's free-flowing condition, water quality, and the unique values that has made the ...
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MRP River Values Draft Baseline Conditions Report - PEPC
The Merced River and South Fork Merced River in Yosemite National Park are congressionally designated wild and scenic rivers, pursuant to the Wild and Scenic ...
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Merced River Instream and Off Channel Habitat Restoration Project
In total, the Instream and Off Channel Habitat Restoration Project consisted of re-grading and enhancing more than 7-acres of riparian and upland habitat. It ...
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[PDF] Merced River Corridor Restoration Plan Phase IV
Riparian vegetation dynamics on the Merced. River. Proceedings of the Riparian Habitat and Floodplains Conference. March 12-. 14, 2001. Sacramento, California ...
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How Sport Fish Restoration Act Funds Are Rebuilding Salmon and ...
Sep 29, 2025 · Back on the Merced River, heavy equipment continues to rebuild riffles and side channel habitat. Fresh gravel sits in place, waiting for ...