Secondary and Cumulative Impacts Master Management Plan - 2014

TOWN OF MORRISVILLE

As the land use within the Planning Area changes, the amount of impervious surface will increase, which not only changes the viewshed, but also affects surface and groundwater flow, as described in Section 5.10. Table 5-2 includes percentage imperviousness; the values listed were used in modeling analyses performed for the Town of Cary in its Northwest Area (CH2M HILL, 2002a). These values are based on literature values. Based on these impervious values, an impervious area for each land use was estimated. These were then summed and divided by the total land area to estimate the overall impervious value for future land use conditions. It is estimated that in the future just over one half of the Planning Area could be developed into impervious surfaces. The 2035 Land Use Plan does not include categories for forested and agricultural land. As described above, the 2035 Land Use Plan is a guidance document that indicates the land use the Town prefers, if land is developed. Agricultural land is allowed as a land use within the very low density residential zoning category, but there are no active farms within the Town. Similarly, currently forested land may remain as forest. The largest changes between the existing and future land use will be the reductions in forested land and the increases in industrial and office, and institutional development. Forested and agricultural land will continue to decrease as low- and medium-density development replace it. Even without the proposed infrastructure, growth is likely to occur in the Planning Area, given the Town’s proximity to RTP and the strong local economy; however, the pattern and rate of growth will be different between these two scenarios. The Town has mechanisms in place to protect open space through the development process, as presented in Section 6. Stream buffers, required open space in subdivisions along with clustered development, landscape buffers between different land uses, park lands, and greenways will limit the impacts to open space. For these reasons, Table 5-1 underestimates the amount of open space under future conditions. Approximately 10.8 percent of the future land within the Planning Area is expected to be protected as open space. This number is likely underestimated as the riparian buffer, floodplain, and open space are often included in the other land use categories. Figure 4-1 illustrates the riparian buffers within the Town’s Planning Area, and these buffers account for 1.8 square miles (or 18 percent of Planning Area). The floodplain area inside the Planning Area is 0.7 square mile (or 7 percent of the Planning Area). These areas are not separated from the land use categories listed in Table 5-2. Other areas within development areas, such as perimeter buffers, are actually open space. Finally, some planned parks are categorized as undeveloped and not open space. 5.4 Wetlands Wetlands in the Planning Area are located primarily within the riparian zones or floodplains of streams and lakes. Wetland losses may occur as land use changes occur and population density increases in the Planning Area. Wetland loss can result in habitat loss, habitat fragmentation, and reduction in species diversity. As discussed in Sections 4 and 6, the majority of wetlands will be protected by existing floodplain regulations. Other programs that protect wetlands are described in Section 6.

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