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<br />areas may contribute a much greater amount of salinity to the river system, and may cause <br />problems with selenium concentrations. When preparing designs for specific systems, the <br />design team should take measures to avoid or minimize impacts to wetlands of sufficient <br />value only if they do not contribute significant amounts of dissolved solids to the river <br />system, nor contribute to selenium concentration problems. <br /> <br />To avoid or reduce losses of mature cottonwoods, designers should try to avoid unnecessarily <br />clearing trees in concert with affected landowners. They should consider if water supplies <br />are available to sustain trees. If not, leaving snags would preserve values to wildlife. Most <br />losses are still expected. <br /> <br />For unavoidable losses, the team reformulated the habitat replacement program with the goal <br />of concurrently replacing lost habitat values. Preliminary discussions recognized that <br />wetlands are valuable for aesthetics and recreation as welLas wildlife. The wetlands also <br />have hydrologic functions such as water quality control (i.e., removal of excess nutrients, <br />sediment control, breakdown of pesticides) and groundwater recharge. Hydrologic values <br />rated very low because most of the affected wetlands are next to laterals and do not intercept <br />runoff from fields. <br /> <br />Another wetland mitigation policy is to replace losses in the same area with wetlands of <br />similar value and function. The study team recognized several factors limit this goal. First, <br />development of new wetlands in the same area would conflict with salinity control. They <br />would create new areas of recharge to the underlying saline soils and formations. Second, <br />wetlands developed on the Mancos Shale Formation may create other water quality problems, <br />such as increasing selenium concentrations. Third, developing many small sites among <br />privately-owned agricultural lands would create difficulties with long-term protection and <br />management of replacement lands. The team prefers to create or enhance wetlands along the <br />river corridors to avoid these problems. Riparian areas are natural to the area. Many <br />studies show they have extremely high values to wildlife, aesthetics and recreation. These <br />areas have been impacted significantly in Colorado over the last 100 yean by transportation <br />corridors, agricultural uses, reservoir sites, and channel improvements and dikes to protect <br />lands from flooding. <br /> <br />Another priority for wetland mitigation is to replace wetlands with the same type. This <br />would result in creation of areas with 75 percent emergent (dominated by lower value species <br />such as salt grass), 23 percent shrub-scrub, and 7 percent forested wetlands. The impacted <br />emergent wetlands are most commonly small, salt grass flats that are low in diversity. The <br />team prefers to mimic communities that are natural to the area and more diverse, i.e., <br />manage for a mix of native communities dominated by cottonwoods, willows, broad-leaved <br />emergents and open water. Activities should emphasize restoration of native cottonwood and <br />willow communities to meet needs of representative wildlife species of concern. <br /> <br />Table 5 summarizes habitat replacement estimates for losses associated with each lateral <br />system. (See Attachment B for the data on each lateral system summarized by this table.) <br /> <br />20 <br />