Introduction
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Introduction The Santa Ana River Watershed historically contained an abundance of natural resources, including water captured from snowmelt in the local mountains, diverse wildlife populations, abundant aquatic life in streams and coastal waters, geological resources for building materials, and a wide range of plant communities from coastal sage, to wetlands, to evergreen forests. These assets were first utilized by Native Americans and then by European settlers, who began to change the land use in the watershed with irrigation and farming. Over the past 200 years, human population has increased greatly in the Santa Ana River Watershed. Since the 1930s, controlling floods and providing a reliable water supply have taken precedence over other critical watershed issues. These priorities have changed the natural hydrology of the Santa Ana Watershed, diminishing the once abundant natural water resources in the region. This strain on water resources and associated urbanization has left only remnants of isolated habitat in highly populated areas. Other factors including invasive plant species, frequent local fires and rogue recreational uses also have contributed to a reduction or complete loss of available habitat in some areas. The natural resources and habitat in the Santa Ana River Watershed are now a fraction of their historical values. Therefore, efforts must be made to sustain and conserve the remaining resources for the benefit of future generations of life in the ecosystems of the watershed, and even expand them where possible. The purpose of this chapter is to detail the current status of these natural resources, including their benefits as both habitat and recreational assets, and to identify opportunities to promote and 1 | Natural Resources Stewardship implement sustainability followed by recommendations for solutions that maintain ecological balance and economic health. Resources of the Santa Ana River Surface Water Water is the key life-sustaining resource within the Santa Ana River Watershed. The river begins high in the San Bernardino Mountains, where it flows westward for approximately 18 miles and then picks up additional flows from Bear Creek, a major tributary. The river then runs southward and meets up with Seven Oaks Dam, which provides capacity for flood control and also serves as a reservoir, with a total capacity of 145,600 acre-feet. The released flows from the Seven Oaks Dam continue westward with additional flows into the river contributed by Mill Creek, City Creek, San Timoteo Creek, Warm Creek, Twin Creek, Cajon Creek, and Lytle Creek before reaching the reservoir at Prado Dam. The Prado Basin also is fed by Chino Creek and another stream named Mill Creek, and occasionally by Temescal Creek in wetter years. Water released from Prado Dam continues westward into Orange County, where the river then is diverted into spreading grounds for groundwater recharge in the north Orange County aquifer. Any remaining flows are confined to concrete channels between earthen levees, and additional flows are received from Santiago Creek, located near the city of Anaheim. The flows continue in a concrete flood control channel until crossing Interstate 5 near the city of Santa Ana, where the river again flows through a soft-bottom channel before reaching its mouth between Huntington Beach and Newport Beach. Much of the river’s historical flows have been diverted for local use along its path. The majority of water that currently flows in the Santa Ana River during the non-rainy season now comes from effluent from wastewater treatment plants. The Santa Ana River Watershed has one natural and several manmade lakes that retain water for use as drinking water, irrigation, recreation, and habitat for aquatic species. Big Bear Lake is manmade and resulted from the construction of a dam along Bear Creek to hold back the runoff and snowmelt for the purpose of providing a reliable source of irrigation water for citrus growers near Redlands. Recreational boating and fishing are also beneficial uses of Big Bear Lake. Lake Perris, located in the eastern side of the Santa Ana River Watershed, is also manmade. Completed in 1973, Lake Perris is the terminus of the State Water Project and is used as a recreational amenity for the region. Lake Mathews, also manmade, is located in the foothills of the Santa Ana Mountains and functions strictly as a drinking water reservoir. It is the terminus of the Colorado River Aqueduct. Lake Elsinore is a natural lake that offers recreational boating and fishing. In recent years, the lake has been replenished with recycled water. Mystic Lake, in the San Jacinto Basin, is an ephemeral lake that appears in wetter years, receiving waters from overflows from the San Jacinto River. 2 | Natural Resources Stewardship Minerals The geological composition in the Santa Ana Watershed has developed over a long period of time by the forces of natural seismic events and climate changes that affected the course and volume of the Santa Ana River. As flows from tributaries carried and deposited sediment along its varied alignments, areas referred to as alluvial fans were created. Most of the watershed from the base of the San Bernardino Mountains and north of the Santa Ana River are comprised of marine and non-marine sedimentary rocks. On the south, in the area of the Cleveland National Forest, shale, sandstone, limestone and slate dominate the geology. The San Bernardino Mountains’ geology consists largely of a composite of Precambrian igneous and metamorphic rocks and Mesozoic granite. The greatest mineral economic resource in the region is in aggregate, which can be in the form of natural sand and gravel, or produced by crushing rock. It is valued for its many uses in construction such as in Portland cement concrete, asphaltic concrete, road base, railroad ballast, and rip-rap. The California Geological Survey estimates that current permitted mining for this resource in the Santa Ana River Watershed region will meet only 25 percent of the estimated local demand. Importing this resource from other than local sources will result in higher project costs for all types of construction and have negative environmental impacts. Mining, however, also has been associated with negative environmental impacts including noise, dust, and habitat destruction. Mitigation of these impacts results in a lengthy process of five to ten years to acquire permits, which has greatly reduced the amount of aggregate mined in the region despite its abundance. Vegetation in Habitat Areas Habitat classifications can be very complex, and while complex information is available for interested parties, this document will refer to several generalized groups, including alluvial fan, riparian, wetland, coastal, chaparral, and forested habitats. Alluvial fans are located where stream flows that originate in mountainous areas flatten and spread out. Fan-shaped deposits of sand and gravel sediment, brought down from higher elevations, are left in the wake of storm and flood events, building up over time. They also can be found in desert areas that are prone to flash floods. Alluvial fan areas create a unique habitat in the Santa Ana River Watershed, but most significantly, they are home to both endangered and threatened plants and animals. They also are in areas where historical groundwater recharge has occurred, increasing the importance for conservation of alluvial fan areas. Riparian habitats are those areas that transition between land and rivers or streams, and sometimes are referred to as buffer zones. These riparian zones provide valuable wildlife habitat and serve as wildlife corridors, allowing for increased biodiversity by enabling wildlife, including aquatic life, to move freely along river systems. Keeping this connectivity intact is vital in avoiding development of isolated communities. According to the Clean Water Act, wetlands are defined as: "those areas that are inundated or saturated by surface or groundwater at a frequency and duration sufficient to support, and that under normal 3 | Natural Resources Stewardship circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions.” Wetlands serve as vital habitats for a wide range of birds and aquatic creatures. Coastal habitats consist of a combination of beaches and intertidal wetlands, which meet the definition of wetlands above. Chaparral is comprised of hard-leafed evergreen shrubs that grow two to four meters tall with deep roots. An understory layer rarely exists. Chaparral habitat occurs in different types of terrain including plains, rocky hills, and mountain slopes. Forested habitats exist mainly in the higher elevations of the watershed. Wildlife Birds Riparian ecosystems harbor the highest number of bird species in the watershed. Riparian habitat provides productive breeding grounds and offers vital over-wintering and migration stop-over areas for migrating birds. Loss and degradation of riparian habitat have negatively impacted bird populations throughout the watershed. Other factors affecting bird populations are brood parasitism by the brown- headed cowbird, and disruption of natural hydrological regimes from dams and levees. The federally endangered least Bell’s vireo has experienced recent population growth within the watershed due to aggressive management activities that started within Prado Basin and spread to other riparian areas throughout the watershed. In 1986 there were only 16 pairs of vireos reported breeding in the