5. Significant Environmental Impacts

5.1. Summary

The proposed project would have unavoidable significant adverse impacts on land use, visual resources, mineral resources, and air quality.

Under Alternative 1, the "no project" alternative, the proposed project would not be constructed and, therefore, no adverse environmental impacts would occur and no project objectives would be met.

Alternative 2, the Middle Corridor alternative, would have similar air quality impacts as the proposed project. It would have fewer impacts to land use and visual resources than the proposed project, although these impacts would remain significant and unavoidable. It would avoid impacts to mineral resources. However, due to its geographical remoteness, Alternative 2 would not serve the project objective of being able to be used for connections to potential future electrical facilities in the Valley South System.

Alternative 3, the Central Region Route Segment alternative, would have fewer impacts to land use and visual resources than the proposed project, although these impacts would remain significant and unavoidable. It would result in similar impacts to air quality and mineral resources as the proposed project.

Alternative 4, the Fogarty Substation alternative, would result in similar impacts to air quality, land use, mineral resources and visual resources as the proposed project.

Alternative 5, the Warm Springs-Pacific Clay alternative, would have similar impacts to land use and air quality as the proposed project. However, it would have fewer impacts to visual resources than would occur with the proposed project, and would avoid impacts to mineral resources.

Alternative 6, the Eastern Region Route Segment alternative, would avoid impacts to mineral resources, but it would have greater impacts to air quality, land use, and visual resources than the proposed project.

Alternative 5, the Warm Springs-Pacific Clay alternative, is the environmentally superior alternative.

5.2. Land Use

The proposed project would conflict with applicable land use plans. Land Use Element 13.5 of the Riverside County General Plan requires new or relocated electric or communication distribution lines which would be visible from Designated and Eligible State and County Scenic Highways to be placed underground. The proposed subtransmission line would have a significant visual impact on State Route 74 and Interstate 15, which are eligible State Scenic Highways. The proposed subtransmission line would contribute to the substantial cumulative degradation of visual resources that is occurring due to the rapid residential and commercial development in southwestern Riverside County. This impact to land use would be significant and unavoidable.

Alternative 2 would traverse through remote areas away from State Route 74 and Interstate 15 and would not have a significant impact on those Eligible Scenic Highways. However, it would pass through areas with a generalized land use designation of Open Space Conservation, on which the construction of access roads would have a significant and unavoidable impact.

Alternative 3 would have fewer impacts to land use than the proposed project as it would be located further from State Route 74. However, its impacts to land use would still be significant and unavoidable.

Alternatives 4 and 5 would have similar impacts to land use as the proposed project.

Alternative 6 would have greater impacts to land use than the proposed project because it would pass along a longer stretch of State Route 74.

5.3. Visual Resources

As discussed above, the proposed subtransmission would be visible from State Route 74 and Interstate 15, which are eligible State Scenic Highways. The new subtransmission line would contrast sharply with vivid views along the highways. Similarly, the proposed Fogarty Substation facilities would detract from the scenic resources visible from Interstate 15. In addition, construction activities, including the removal of vegetation and use of construction signs, fencing, and construction equipment, would be noticeable to area residents and motorists. These impacts would contribute to the substantial cumulative degradation of visual resources that is occurring due to the rapid residential and commercial development in southwestern Riverside County. While impacts to visual resources would be reduced with mitigation, they would remain significant and unavoidable.

Alternative 3 would have fewer impacts to visual resources than the proposed project as it would be located further from State Route 74. However, its impacts to visual resources would still be significant and unavoidable.

Alternatives 4 and 5 would have similar impacts to visual resources as the proposed project.

Alternative 6 would have greater impacts to visual resources than the proposed project because it would pass along a longer stretch of State Route 74.

5.4. Geology, Soils, and Mineral Resources

The proposed subtransmission line would bisect an active clay mining operation owned by Pacific Aggregates, also referred to as Pacific Clay, which is a locally important mineral resource recovery site located on the western side of Interstate 15 at Nichols Road in Lake Elsinore. Construction of the poles amidst the active mining operations would remove the clay deposits beneath and surrounding the poles from production. This impact to the mineral resource recovery site during construction and operation would be significant and unavoidable.

Alternatives 2, 5 and 6 would avoid the Pacific Clay Mine and would not have an impact on mineral resources.

Alternatives 3 and 4 would have the same significant and unavoidable impacts to mineral resources as the proposed project.

5.5. Air Quality

Project construction activities would generate emissions of nitrogen oxide, volatile organic compounds, and particulate matter less than or equal to ten microns in diameter and 2.5 microns in diameter in excess of corresponding South Coast Air Quality Management District mass daily significance thresholds and approximately 4,229 metric tons of carbon dioxide (CO₂) from vehicles, equipment and fugitive dust. During operations, approximately 34 metric tons of CO₂ would be emitted from vehicles used during maintenance and inspection and from circuit breaker leakage. While emissions would be reduced by the implementation of mitigation measures, the impact to air quality in the basin would still be significant and unavoidable.

Alternatives 2, 3, 4 and 5 would have similar impacts on air quality as the proposed project.

Alternative 6 would have greater impacts on air quality as the proposed project because it would pass through areas with a greater number of sensitive receptors and, due to its greater length, would require more construction.