Aquatic – Riparian Conservation
Aquatic and riparian habitats are linked in direct and complex ways and are fundamentally dependent on natural flows of water. Californians have engineered extensive control over the waters of the Sierra Nevada changing these natural flows. Aquatic ecosystems are very important to species of the Sierra Nevada with 17% of Sierran plant species, 21% of the vertebrate species, and almost 100% of aquatic invertebrate species dependant on riparian or wet areas.
Due primarily to human activities and disturbances, aquatic and riparian habitats have been severely altered and continue to deteriorate, leading to the loss of native species, ecosystem functions, and services to human society. Of sixty-seven types of aquatic habitat categorized in the Sierra Nevada, almost two-thirds (64%) are declining in quality and abundance, and many are at risk of disappearing altogether.
The Sierra Nevada Framework Plan seeks to protect these important natural areas by creating Critical Aquatic Refuges and Riparian Conservation Area management guidelines to preserve, enhance and restore water quality and key habitats for sensitive or listed species that will contribute to their viability and recovery. This includes restrictions on grazing and peer review of any activities that may affect aquatic resources. The revisions to the Framework Plan weaken in grazing standards in aquatic areas and will not be developed at the bioregional scale. Furthermore, mechanical treatments will be used on more acres for fuels reduction and “forest health” logging, despite the Forest Service knowledge that mechanical treatments “have more potential for adverse effects” on aquatic habitats. Aquatic and meadow-dependent species that are at-risk include a variety of native fish, the Yosemite toad, Mountain yellow-legged frog, Willow flycatcher, and Great Gray owl.
The revisions to the Framework Plan weakened the grazing standards in aquatic areas and have not been developed at the bioregional scale. Furthermore, mechanical treatments will be used on more acres for fuels reduction and “forest health” logging, despite the Forest Service knowledge that mechanical treatments “have more potential for adverse effects” on aquatic habitats.
Multiple stressors have negatively affected rivers, streams, and wet meadows in the region. Dams and water diversions throughout the region have profoundly altered stream-flow patterns, increased water temperatures, and degraded aquatic ecosystems. Dams and reservoirs have also blocked animal migration routes. Livestock grazing, eroding forest roads, timber harvest activities, development, and recreational activities have also contributed to the fragmentation of riparian habitats, caused bank erosion, and increased sediment and nutrient runoff into aquatic ecosystems.
One of the main threats to aquatic and riparian habitats is poorly managed and excessive grazing. Riparian habitat is often trampled by cattle seeking water and cool shady areas in the hot Sierra summers. Additionally, the increased erosion from cattle and the resulting siltation into aquatic areas is of great concern for species dependent of clear, clean water. In some areas grazing needs to be eliminated altogether, while in others, a significant reduction on the amount of grazing is necessary to ensure that these critically threatened habitats are given the chance to recover.
The Sierra Nevada Ecosystem Project highlighted aquatic and riparian ecosystems as vital to the sustenance of wildlife diversity. Deterioration of these vital aquatic and riparian habitats has contributed to the decline of native fish and amphibians as well. Wildlife species that depend on these habitats, including the Sierra Nevada willow flycatcher, Mountain yellow-legged frog, California red-legged frog, and the Yosemite toad are either declining or facing an uncertain future. In the Sierra Nevada, of the 83 terrestrial species dependent on riparian habitat, 24 percent are at risk. Aquatic insects and other invertebrates, important prey for fish and amphibians, have also been affected by habitat changes. Six of the 40 native fish of the Sierra are listed as threatened or endangered and only half of the 40 species have secure populations (Moyle et al. 1996). Among the fish species at risk in the region are several of California’s native trout, including the Little Kern golden trout and Lahontan and Paiute cutthroat trout. Half of the 29 native amphibian populations of the region are at risk of extinction. Decades of stocking fish for recreational fishing have contributed to the decline of native fish and frog species in the region. Stocking of trout into historically fishless high mountain lakes has contributed to the extirpation of native amphibians in some basins, with particularly severe consequences for the once-common mountain yellow-legged frog.