Big Dalton Wash

Big Dalton Wash
Name	Big Dalton Wash
Country	United States
State	California
Region	San Gabriel Mountains
County	Los Angeles County
Source	San Gabriel Mountains
Mouth	San Gabriel River watershed
Length	~? km
Basin countries	United States

Big Dalton Wash is an ephemeral stream and seasonal drainage in the San Gabriel Mountains of Los Angeles County, California, feeding into the greater San Gabriel River watershed. Located near communities such as Glendora, California, Covina, California and Duarte, California, the wash links upland chaparral and montane environments with suburban and urbanized floodplains. As a geomorphic and hydrologic feature it is tied to regional water infrastructure, wildfire regimes, and Southern California land use history.

Geography

Big Dalton Wash originates on the southern slopes of the San Gabriel Mountains, a range within the Transverse Ranges of Southern California, and descends through steep canyons into the foothill zone near Glendora. The wash traverses terrain shaped by Pleistocene and Holocene tectonics associated with the San Andreas Fault system and local faults such as the San Gabriel Fault. Adjacent landforms and communities include Angeles National Forest, Sierra Madre, California, and the urbanized San Gabriel Valley. Regional transportation corridors nearby include Route 66 historic alignments and modern highways such as Interstate 210 and California State Route 57 that intersect or parallel local drainages.

Hydrology

Flow in the wash is typically episodic, driven by winter frontal storms from the Pacific Ocean and intense convective events linked to the Santa Ana winds and orographic precipitation over the San Gabriel Mountains. Hydrologic responses are influenced by post-wildfire runoff, soil saturation following events like the 1993 Storms in California and subsequent debris-flow hazards recorded in the region. The drainage contributes runoff and sediment to the San Gabriel River system and interacts with engineered channels and detention basins operated by agencies such as the Los Angeles County Flood Control District and the United States Army Corps of Engineers. Water quality and seasonal baseflow are affected by urban runoff from cities including Glendora, California and Covina, California and by groundwater recharge dynamics tied to the Central Basin (California).

History

Indigenous peoples of the region, notably the Tongva and Tataviam communities, historically used the San Gabriel mountain drainages for seasonal resources and travel. Spanish and Mexican-era land grants such as the Rancho San Dimas and mission-period activities around Mission San Gabriel Arcángel influenced land use in the watershed. American-period development included ranching, timber extraction, and later suburbanization associated with railroad expansion by companies like the Atchison, Topeka and Santa Fe Railway and civic growth in Los Angeles. Flood events in the 20th century prompted construction of flood-control projects under New Deal-era and postwar programs administered by entities including the United States Bureau of Reclamation and the Civilian Conservation Corps. Local responses to wildfires, including those led by the Los Angeles County Fire Department and federal agencies such as the United States Forest Service, have shaped contemporary management.

Ecology

Vegetation in the wash and surrounding canyons comprises montane chaparral, sage scrub, coastal live oak woodlands, and riparian species where perennial seeps occur; these plant communities are characteristic of the California chaparral and woodlands ecoregion. Fauna include regional species such as the California mule deer populations, coyote, various raptors including red-tailed hawk and American kestrel, and amphibians like the California newt in cooler secluded reaches. The watershed provides habitat connectivity between the Angeles National Forest and urban green spaces, supporting native pollinators and migratory birds along the Pacific Flyway. Ecological processes are affected by invasive plant species, altered fire regimes exemplified by events like the Station Fire (2009) in neighboring drainages, and fragmentation from suburban development.

Recreation and Access

Access to the wash and its upper reaches is often via trailheads and access points within the Angeles National Forest and municipal parks in foothill cities such as Glendora, California and Sierra Madre, California. Recreational activities in the corridor include hiking, birdwatching, trail running, and seasonal bouldering; users frequent nearby attractions such as the Glendora Mountain Road viewpoints and trails linked to the Pacific Crest Trail network at regional scales. Management of public access involves coordination among agencies like the Los Angeles County Department of Parks and Recreation, the United States Forest Service, and local municipal authorities, balancing recreation with hazard warnings during flood seasons and post-fire closures enforced after incidents similar to the Station Fire (2009).

Infrastructure and Management

Historic and contemporary infrastructure in the wash includes engineered channels, low-water crossings, culverts, detention basins, and grading tied to flood-control programs by the Los Angeles County Flood Control District and stormwater management plans under the California State Water Resources Control Board. Watershed management involves multi-agency collaboration among municipal governments of Glendora, California, Covina, California, and Duarte, California as well as federal partners like the Federal Emergency Management Agency for floodplain mapping and disaster response. Land-use planning and hazard mitigation efforts draw on regulatory frameworks and planning entities such as the Los Angeles County Board of Supervisors and regional planning bodies to address sedimentation, debris flows, and impacts of urban runoff on the San Gabriel River and downstream water infrastructure.

Category:San Gabriel Mountains Category:Rivers of Los Angeles County, California