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Table 2.--Blot teal data for ¦ le wetland. Lower Ounnlson silver Basin Colorado 1970 No. Snell No. No. Spring Large Native Wildlife minant D Mammal Swell Spring Breed l ng Mammal Plant INbl tat Wildlife Wetland o Wetle d Wet" Slze Catch/1B0 Mewnel Breedl 4 Bird Obser- Condl- Val" 5 use 6 Number Cl ass Sou ce Locatlon3 (he) Trapnlahts SDD /Slte Birds/ha SpD /Slte vatlon tlon Rating Ratinm 507-555 Forest Nat R 33.9 9 3 14 20 X 3 113 7a 23 13 548-477 Scrub/shrub Can W 0.7 3 2 23 10 0 3 7 15 549-537 Scrub/shrub IN E 3.5 B 3 12 11 0 3 3 2 64 16 549-538 Emergent/nl IN E 0.2 11 4 26 4 0 3 72 13 551-481 Emergent/nl Can M 2.0 4 3 27 II 0 3 90 24 555-489 Scrub/shrub Can W 8.0 9 3 21 19 X 1 84 4 560-564 Emergent/nl Can E 17.2 0 0 2 6 0 3 111 21 562-474 Forest Can W 4.4 2 2 27 21 X X 3 77 22 574-510 Forest IN R 1.5 6 2 34 15 3 76 6 596-449 Emergent/n1 Can W 4.9 0 0 4 11 0 3 90 11 607-542 Emergent/nl IN E 9.5 2 2 13 9 0 5 too 24 616-412 Forest Can M 2.4 4 3 31 14 X 0 3 Be 17 619-SB2 Scrub/shrub ca. E 6.7 6 2 31 16 X 3 98 21 628-589 Scrub/shrub Nat E 17.6 11 2 19 14 X 3 105 22 676-410 Scrub/shrub Nat if 78.6 7 I 8 26 86 15 703-388 Scrub/shrub IN M 2.2 5 2 21 14 0 3 3 89 17 754-455 Scrub/shrub Net E 34.3 9 2 30 16 0 102 17 755-610 Scrub/shrub IN M 3.6 3 2 20 12 X 3 70 15 767-461 Scrub/shrub Can E 2.2 a 2 31 6 0 3 a 811-458 Emergent/nl Can E 42.0 1 1 1 4 0 3 Bo 29 812-612 Scrub/shrub IN R 3.0 13 3 13 if X 3 98 813-395 Emergent/water Nat R '7.8 17 4 38 21 X 3 114 29 615-564 Emergent/nl IN W 1.6 7 3 to 2 0 1 53 lie 9 17 852-601 Forest Nat R 46.8 2 1 14 15 X X 3 3 114 21 864-479 Scrub/shrub Nat W 64.9 3 3 6 23 1 55 11 886-5f9 Emergent/nl IN W 0.2 4 2 43 3 0 886-539 Forest IM W 0.2 4 2 75 4 0 1 3 70 102 13 29 921-591 Emergent/water Nat E 5.6 23 3 32 I8 X 922-506 Emergent/nl Nat W 15.7 9 2 10 23 X 3 90 1 22 32 938-570 Ewer ant/water Nat R 11.0 30 4 32 If X 3 15 IUSFMS classlflcatlon (Cowardln at al, 1976). 2Natural, Canal, Irrigation Management. 3East of Uncompahgre River, West of Uncompahgre River, R!verbottom of Uncompahgre or Ounnfson rl-a. 4Wetland rating based on presence and dominance of native plant species relative to reedy apsciae. 5Ratings after Golat (1973, 19730. 6Rating can range from 0-50. WETLAND LOSSES - PAST AND POTENTIAL Historically the major rivers in the Lower Gunnison River Basin are thought to have supported 4,6905 ha of wetlands of which 3,120 ha remain; a loss of about 33 percent. Most of the lost wetlands were converted into cropland, while the wildlife values of those remaining are decreasing because they are subjected to a variety of other uses. A total of 8,773 ha of wetlands was in- ventoried in this study, with wetlands sup- ported by natural water sources comprising 60 percent or 5,264 ha. We do not believe that salinity control activities will adversely impact natural wetlands. However, landusers may decide, without project assistance, to convert some of these wetlands to cropland, irrigating them with water saved by more efficient water management. supported totally or partially by irrigated agriculture using the 30 m3/s of Gunnison River water that is diverted into the Uncom- pahgre Valley. Wetland losses would result from concrete lining or piping canals, laterals and on-farm ditches; closing and piping open drains; improved irrigation water use efficiency and other improvements. Actual project-caused wetland losses cannot be calculated until various alterna- tives are considered. Economic considera- tions suggest that something less than total project implementation may occur. Regardless of degree of implementation, there will be wetland losses. Salinity con- trol efforts and maintenance of wetlands now existing in the Lower Gunnison Basin will often be incompatible; choices and compro- mises will have to be made. The remaining 40 percent (3,509 ha) could be destroyed or altered if salinity control measures were fully implemented. These are irrigation-induced wetlands, 5The total of Alluvial, Wet Alluvial, Saline Wetland and Uncompahgre soils (Cline et al. 1967), all wet soils lying adjacent to the rivers and supporting hydrophytic growth in their natural state. DISCUSSION Mitigation is both a concept and an act. Typically it has meant replacement, but it can include minimizing adverse impacts and enhancing remaining wildlife habitat to increase the per unit habitat value. With this in mind, the following suggestions are made for mitigating wetland losses in the Lower Gunnison River Basin. 314