WHO Technical Report

The Feather River Coordinated Resource Management Group (FR-CRM) has been restoring channel/ meadow/ floodplain systems in the Feather River watershed since 1985. Project and watershed-wide monitoring has shown multiple benefits of this type of work. With the concern over global climate change, the group wanted to measure the carbon sequestered in project areas. No protocol was found to measure carbon stores in native Sierra Nevada meadows. Plumas County funded the FR-CRM to conduct a pilot study to develop such a protocol. The sampling protocol included discrete sampling at consistent soil depths to determine the vertical distribution of carbon. A Technical Advisory Committee developed and refined a multi-project sampling protocol for three restored meadows and three un-restored meadows. Data from the un-restored meadows will also provide base-line data for before and after restoration comparisons. Initial data analysis indicates that restored meadows contain twice as much total carbon as degraded meadows; on average approximately 40 tonnes more carbon per acre. Virtually all of the additional carbon in restored meadows occurs in the soil, and is thus protected from loss via grazing, haying, wildfire, etc. Introduction In 1994 the Feather River Coordinated Resource Management (FR-CRM) group shifted its stream restoration approach from bank stabilization to landscape function. Called meadow re-watering, this approach entails returning the incised stream channel to the remnant channel(s) on the historic floodplain and eliminating the incised channel as a feature in the landscape. Historic channel incision resulted in significant land degradation as the adjacent groundwater levels dropped commensurate with the incising stream bed. Vegetation conversion rapidly follows as deep, densely rooted meadow plant communities convert to xeric shrubs and other plants. After a decade of meadow restoration, the FR-CRM recognized the possibility of a significant change in carbon stocks in these restored meadows and valleys. Plumas County has been a leader in advocating for investment in watershed ecosystem services such as water storage and filtering, and now, carbon sequestration. The county provided funding for the FR-CRM to conduct a pilot study of carbon in biomass and soils. Watershed Location and Characteristics The upper Feather River watershed is located in northeastern California encompassing 3,222 square miles that drains west from east of the Sierra crest into Oroville Reservoir and thence to the Sacramento River. Annual runoff produced from this watershed provides over 1,400 MW of hydroelectric power, and represents a significant component of the California State Water Project, annually providing 2.3 millionacre feet of water for urban, industrial and agricultural consumers downstream. The Feather River watershed is primarily comprised of two distinct geologies: the Sierra Nevada granitic batholith of the western third of the watershed; and Basin and Range fault-block meta-volcanics, metasedimentary and recent basalts in the eastern two-thirds. It is the Basin and Range zone (Diamond Mtns.) of the watershed that has been the primary area of restoration. This geologic mélange of faulted and weathered rock has resulted in over 390 square miles of expansive meadows and valleys comprised of deep fine grained alluvium, shown as green and yellow in Figure 1. Figure 1. Upper Feather River Watershed Upper watershed meadows and valleys (shown as green/yellow in Figure 1), often dozens of miles in length, once supported a rich ecosystem of meadow and riparian habitats, for coldwater-loving trout, a diversity of wildlife, and indigenous peoples during the dry summers of California’s Mediterranean climate. The densely rooted vegetation, cohesive soils and expansive floodplains all contributed to the sustainability of these meso-scale floodplain meadows, with associated alluvial fans. River system segments are often characterized simplistically as transport and depositional reaches. Depositional reaches feature lower gradients and a more expansive fluvial setting. These landscape attributes, in conjunction with the type and quantity of sediment, debris and nutrients, are what provide for the development and evolution of meso-scale “sinks” or “warehouses”, for the hydrologic products of the basin. Viewed as a macro-hyporheic corridor ( Harvey and Wagner, 2000; Boulton, et.al., 1998; Stanford and Ward, 1993) these features are crucial as a landscape zone of active mass and energy transfer as well as an active storage reservoir for water, sediment and nutrients. The long-term recruitment and evolution of these features involve physical, Figure 2. Typical Alluvial Features biological and chemical synthesis within the natural variability of fluvial processes. Euro-American settlement of the watershed began in 1850 with gold mining in the western portions of the watershed and, soon thereafter, agricultural production in meadows to support the mining communities. Dairy farming, horses (for cavalry mounts), sheep and beef cattle were some of the early intensive disturbances that led to localized channel incision. The resultant lowering of shallow groundwater elevations began to alter and weaken the vegetative structure of the system. Soon, near the burgeoning communities in the mid-elevation valleys, a permanent road system was established with frequent channel manipulation and relocation efforts to simplify drainage and minimize bridge construction, again leading to localized incision. In the early 1900’s both an intercontinental, and numerous local, railroad systems were constructed throughout the watershed. The local railroad networks, for the purpose of both mining and logging, were routed through the long low-gradient valleys for ease of construction. These valleys were still relatively wet at that time so elevated grades were constructed using adjacent borrow ditches. By 1940, the severe morphological changes imposed by the railroad grades, in conjunction with the above referenced land use impacts resulted in rapid, severe systemic incision of many upper watershed meadow systems. In the mid 1980’s numerous watershed stakeholders adopted a statutory authority that allowed for Coordinated Resource Management and Planning (CRMP). Twenty-four federal, state and local, public and private entities now form the Feather River Coordinated Resource Management (FRCRM) group to adopt, support and implement a watershed-wide restoration program. FR-CRM Restoration Approach & Background The FRCRM began an ongoing implementation program to address these watershed issues in 1990. Initially, these projects focused on geomorphic restoration techniques (Rosgen, 1996) to stabilize incised stream channels. While overall success was encouraging, the projects illustrated the concept that any restoration work in the incised channels was subject to elevated stresses even in moderate flood events (510 year return interval). Concurrently, the benefits from this approach were localized and limited to reduced erosion, and incremental improvement of aquatic habitats and water quality. Little overall improvement of watershed conditions was being realized (Wilcox, et al 2001). This led to re-evaluating restoration approach to encompass the entire historic fluvially-evolved valley bottom. Called meadow re-watering, this approach entails returning the incised stream channel to the remnant channel(s) on the historic floodplain and eliminating the incised channel as a water conveyance feature in the landscape (Figures 3 & 4 and photos 1a, 1b, 2a & 2b). Simultaneously, the FRCRM had received a project assistance request from the United States Forest Service, Plumas National Forest (PNF) to develop restoration alternatives for Cottonwood Creek in the Big Flat Meadow (Photos 2a & 2b). FRCRM staff, led by Jim Wilcox, began conducting surveys and data collection that included the entire relic meadow from hillslope to hillslope. This data collection effort quickly pointed to the nascent meadow re-watering technology as a likely restoration alternative. Figure 3. Typical cross-section, showing pre-project incision, post-project plug elevation, and the new channel. Photos 1a and 1b below show this same cross-section, however, the entire gully is not shown in the pre-project photo. Photo 1aClarks Creek Pre-project, July, 2001 Photo 1bClarks Creek Post project, July, 2006 The rocks in the background of photos 1a and 1b can be used for reference. Because the new channel is in a different location, the photo point also moved in order to show the channel in the preand postproject conditions. Figure 4. Typical cross-section, showing pre-project incision, post-project plug elevation, and the new channel. Implemented in 1995, this project quickly validated the fundamental soundness of this approach. The one mile long, 47 acre project produced elevated shallow groundwater levels, eliminated gully wall erosion, filtered sediments delivered from the upper watershed, extended and increased summer baseflows, and reversed the xeric vegetation trends resulting in improved terrestrial, avian and aquatic habitats. These benefits persisted despite withstanding a 100-year RI (return interval) flood in 1997. Photo 2aBig Flat Pre-project, Dec.,1993 Photo 2bBig Flat Post project, May, 2006 The success of this initial project led to the implementation of an additional 18 projects utilizing this technology (Table 1.). Varying in scale and watershed characteristics, these projects have restored another 20 miles of channel and 5,000 acres of meadow/floodplain. Carbon Sequestration Qualitatively, these projects appeared to significantly increase organic carbon stocks through the much increased root mass as well as increased surface growth, and, possibly, through the more effective hyporheic exchange throughout the meadow. The purpose of the following protocol is to quantitatively establish the effe