Eureka

In 2008, an accident involving a diesel truck released 4000 gallons of red-dyed diesel fuel into an inboard ditch along Highway 199 in Del Norte County, CA. Diesel fuel soaked the ground through the road prism and into the gravel bar adjacent to Smith River, a federally-designated wild and scenic river. GHD was selected to lead the emergency response, including efforts to contain the spilled diesel and prevent impacts to the Smith River.

This project was challenging due to the steep forested slopes, the urgency of cleanup and the magnitude of the spill. Our team worked with nine contractors and 12 public regulatory agencies in a showcase of collaborative effort between stakeholders toward a common goal. The remediation strategy negotiated with stakeholders was a combination of source removal, flushing of the road fill, and recovery and treatment of the water used for flushing. Only 117 days after the spill occurred, regulatory agencies concurred that necessary remediation and restoration were satisfactorily complete.

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Working with a number of public agencies on one of the State of California’s biggest environmental projects, we provided design, permitting, and outreach services to restore more than seven miles of the Salt River and its floodplain and 290 acres of estuarine habitat.

The purpose of the Salt River Ecosystem Restoration Project is to restore historic processes and functions, necessary for re-establishing riparian floodplain corridor, wetlands and estuarine ecosystems as part of a land use, flood alleviation, and watershed management program, to the Salt River watershed. Levees constructed to protect the productive agricultural lands of the Salt River floodplain from the adjacent Eel River’s tidal and flood influences have altered regional drainage patterns, which, coupled with naturally high influent sediment loads, have resulted in accelerated aggradation and loss of stream and sediment transport function and habitat value across the Salt River floodplain. The ongoing aggradation and flooding of local infrastructure and agricultural land have led to loss of habitat for threatened and endangered species, reduced property values, and decline in agricultural productivity.

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GHD participated in the Human Capacity Building in Energy Efficiency and Renewable Energy System Maintenance Project funded by a US Department of Energy 1st Steps Grant. We conducted energy audits of more than 90 percent of the buildings on the reservation, performed solar and micro-hydro energy systems inspection, repairs, and potential siting analyses, and participated in community outreach and staff training in energy issues.

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GHD was commissioned by the Yurok Tribe to improve habitat mapping of the Tribe’s 64,000 acre reservation, which is located along the Klamath River in far northern California. The primary goal was to develop GIS layers that would better enable wildfire risk modelling and to provide an improved basis for habitat conservation planning and forestry practices.

GHD utilised a combination of remote sensing, GIS and field sampling activities to produce a customised vegetation model and habitat classification map. This included an analysis of LiDAR in the context of canopy height, regional geologic and soil data, existing vegetation data, and field validation. An unsupervised spectral classification of 4-band orthoimagery was undertaken to partition the study area into stratified clusters of presumed vegetation categories. Target vegetation classes were then identified via local ecological knowledge, including input from ecologists, timber managers and Tribal members. The result was a preliminary vegetation class model and base map that was used to conduct stratified field sampling for confirmation and training of the model.

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CalFire and the US Forest Service Pacific Southwest Research Station (PSW) worked cooperatively in a comprehensive paired watershed study at the Caspar Creek Experimental Watersheds in Jackson Demonstration State Forest, located in coastal Mendocino County, California. As part of the study, concrete dams equipped with precise flow measurement weirs were constructed providing an essential component of the scientific research. 

In 1964, a wooden fish ladder was built downstream of each weir. To avoid backwatering and submerging the measurement weir, which compromises its accuracy, tailwater levels were kept low requiring fish to leap over a two to three foot water surface drop at the weir. This precluded upstream passage of juvenile salmonids. During low-flow periods, leakage through the wooden fish ladder posed a significant risk of stranding and injury of juvenile salmonids.

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