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Low-Head Hydropower Site Evaluation Impacts

Potential environmental impacts from site evaluation activities are generally temporary and of relatively small magnitude.

Site evaluation phase activities, such as monitoring and site characterization, are temporary and are conducted at a smaller scale than those occurring during the construction and operation phases. Potential impacts from these activities are presented below, by the type of affected resource. The impacts described are for typical site evaluation activities, such as minor amounts of ground clearing (removal of vegetative cover), vehicular and pedestrian traffic, and drilling to characterize subsurface conditions (e.g., soils, depth to groundwater). If excavation or road construction were necessary during this phase, potential impacts would be similar in character to those for the construction phase, but generally of smaller magnitude.

The following potential impacts may result from low-head hydropower site evaluation activities.

Acoustics (Noise)

Activities associated with site evaluation would generate low levels of temporary and intermittent noise. Drilling activities, if required, and the use of larger equipment associated with drilling activities, would generate the most noise during this phase, but impacts would be much lower than those that could occur during construction.

Air Quality (including Global Climate Change and Carbon Footprint)

Impacts to air quality during site evaluation activities would be limited to temporary and local generation of vehicle and equipment emissions and fugitive dust from vehicle traffic and ground disturbances. These impacts are unlikely to cause an exceedance of air quality standards, or impact climate change.

Cultural Resources

Cultural material present on the surface could be disturbed by vehicular traffic, ground disturbances, and pedestrian activity (including collection of artifacts). Drilling and other sampling methods could also affect cultural resources buried below the surface. Site characterization activities could affect areas of interest to Native Americans, depending on their physical placement and/or level of visual intrusion.

Surveys conducted during this phase to evaluate the presence and/or significance of cultural resources in the area would assist developers in designing the project to avoid or minimize impacts to these resources.

Ecological Resources

Impacts to ecological resources (vegetation, wildlife, aquatic biota, special status species, and their habitats) would be minimal during site evaluation because of the limited nature of the activities. The introduction and spread of invasive vegetation could occur as a result of vehicular traffic. Soil borings would destroy vegetation and disturb wildlife.

Surveys conducted during this phase to evaluate the presence and/or significance of ecological resources in the area would assist developers in locating the intake structure; dams or weirs, if required; the powerhouse; the tailrace; and the rights-of-way of transmission lines, canals, and pipelines to avoid or minimize impacts to these resources (e.g., wetlands, migratory birds, threatened species, and endangered species).

Environmental Justice

Site evaluation activities are limited and would not result in significant high and adverse impacts in any resource area; therefore, environmental justice impacts are not expected during this phase.

Hazardous Materials and Waste Management

Impacts from use, storage, and disposal of hazardous materials and waste would be minimal (because of the minimal amounts of hazardous materials used) to nonexistent if appropriate management practices are followed.

Human Health and Safety

Occupational and public health and safety risks normally associated with construction and outdoor activities (working in potential weather extremes and possible contact with natural hazards, such as uneven terrain and dangerous plants, animals, or insects) exist, but are very limited during the site evaluation phase, because of the limited range of activities and number of workers.

Land Use

Site evaluation activities would likely result in temporary and localized impacts to land use. These activities could create a temporary disturbance to wildlife and grazing livestock in the immediate vicinity of the project site while workers are present, which could translate into temporary impacts to hunters and ranchers. There may be visual impacts from the presence of equipment and access roads, potentially impacting the recreational experience.

Paleontological Resources

Paleontological resources present on the surface could be affected by vehicular traffic, ground disturbances, and pedestrian activity (including collection of fossils). Drilling and other sampling activities could also affect paleontological resources buried below the surface; however, the amount of subsurface disturbance is minimal during this phase.

Surveys conducted during this phase to evaluate the presence and/or significance of paleontological resources in the area would assist developers in designing the project to avoid or minimize impacts to these resources.

Socioeconomics

Site evaluation activities are temporary and limited and would not result in socioeconomic impacts on employment, local services, or property values.

Soils and Geologic Resources

Surface disturbance and use of geologic materials are minimal during the site evaluation phase, and soils and geologic resources are unlikely to be affected. Site characterization activities would also be unlikely to activate geological hazards or increase soil erosion. Borings for soil testing and geotechnical surveys provide useful site-specific data on these resources. Surface effects from pedestrian and vehicular traffic could occur in areas that contain special (e.g., cryptobiotic) soils.

Transportation

No impacts on transportation are anticipated during the site evaluation phase. Transportation activities would be temporary and intermittent, and limited to very low volumes of heavy- and medium-duty equipment and personal vehicles.

Visual Resources

Site evaluation activities would have temporary and minor visual effects caused by the presence of workers, vehicles, and equipment.

Water Resources (Surface Water and Groundwater)

Minimal impact to water resources, local water quality, water flows, and surface water/groundwater interactions are anticipated. Relatively limited amounts of water would be used during drilling activities; this water could be obtained locally or it could be trucked in with the drilling equipment.