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Material Damage Standard Twentymile Coal company conducted additional vegetation surveys during the 1986 field season to further characterize the alluvial valley floor regions associated with Foidel, Middle, Trout, and Fish Creeks. The parameter of cover was measured to determine vegetative cover and species composition. Fifty meter transects were randomly located in the field and ten point frames were placed at five meter interva]s. Each transect yielded 100 hits which were used as separate datum. The location of those transects are denoted on Map 1, Salt Loading Study and Land Use. Species cover and composition was determined for the four areas. These values are reported in Table 1, Foidel Creek Alluvial Valley Floor Vegetative Cover, Table 2, Middle Creek Alluvial Valley Floor Vegetative Cover, Table 3, Trout Creek Alluvial Va]ley Floor Vegetative Cover, and 7ab7e 4, Fish Creek Alluvial Valley Floor Cover. The data generated from individual pastures were used to determine the percentage of moderately tolerant and moderately sensitive plant species. Those values for the respective areas are reported on Table 5, Summary of Vegetative Cover of Moderately Tolerant and Moderately Sensitive Species. The following discussion relating to salt tolerance is based on field observations and data, the article "Crop Salt Tolerance - Current Assessment" Maas and Hoffman (1977), as referenced in Rule 2.06.8 (5)(c)(i)(A), and discussions with Dr. Franklin of the Colorado State University Agronomy Department, Mr. Leland Francois and Dr. Maas of the United States Salinity Lab and the Agricultural Research Service, Fort Collins, Colorado. As stated in the referenced article, a species which is considered moderately sensitive may expect some decrease in yield when the soil salinity, measured as ECe, is in excess of 1.5 mmhos/cm. A moderately tolerant species may show evidence of decreased yields at an ECe of 3.0 mmhos/cm. Few of the grasses, forbs, and woody plants growing adjacent to the creeks and in the irrigated pastures have been thoroughly studied; thus, limited information is available. The article of Maas and Hoffman does report salt tolerance levels for some of the genera. Meadow foxtail (A to ecurus pratensis), orchard grass (Dactylis glomerata), and timothy Phleum pratense), are considered moderately sensitive. Although the species Agrostis palustris, which is considered moderately sensitive, was not found in the area, other genera of _A_g~ros~ti~s located in this region were assumed to be moderately sensitive. Smooth brome (Bromus inermis), mountain brome (Bromus carinatus), reed canarygrass Phalaris arundinaceae), tall fescue Festuca elatior which equa~F. pratensis , wheat (Tr iticum aestivum crested wheatgrass (A ro ron desertorum), and s end der wheatgrass (Agropyron trachycaulum are classified as moderately tolerant. Other species of moderately tolerant grasses include barley (Hordeum vulgare) and tall wheatgrass (Agropyron elongatum). It is assumed other genera of Hordeum, Agropyron, and Festuca such as foxtail barley (Hordeum Brach a-n,~t~ie_rum), intermediate w- e~tgrass (Agropyron trach caulumT, westernwheatgrass (A ro ron smithii), wheatgrass Agropyron and Idaho fescue Festuca idahoensis) are moderately tolerant as well. Of the forbs alfalfa (Medicago sativa) and clover (Trifolium) are considered to be moderately sensitive. For the purpose of this discussion, if a particular species had been classified in terms of salt tolerance, such as