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<br />002720 <br /> <br />Opportunities for Ecological Improvement Along the Lower Colorado River <br />Mark Briggs and Steve Cornelius <br />7/24/97 <br /> <br />on-going. Additional riparian recovery efforts are also planned for the immediate <br />future. <br />Pre-Project Site Conditions: Pre-project vegetation consisted primarily of saltcedar, <br />arrowweed, and honey and screwbean mesquite. Soils are mostly sandy. <br />Project Strategy: Prior to project implementation, site characteristics were evaluated <br />with regard to soil salinity, soil texture, and depth to saturated soils. Undesirable <br />plants were removed with a bulldozer. Over 1,200 screwbean mesquite, honey <br />mesquite, cottonwood, coyote willow, and Goodding willow seedlings were planted. <br />The site evaluation allowed revegetation practitioners to develop a detailed map of site <br />conditions, allowing them to place plant materials in areas were they would be most <br />likely survive. Mesquites were planted in areas characterized by relatively high soil <br />salinity (electroconductivity levels in excess of 2 dS m-I). All plants were placed in the <br />ground as seedlings (as opposed to cuttings or poles). Cottonwood and willow were <br />collected for this effort, but the poles were started in a nursery and planted in one <br />gallon containers. Once in the ground, all plants were irrigated with a drip irrigation <br />system. Plants will be irrigated until roots were deemed to have reached saturated <br />soils. <br />Results: Roughly 2/3 of all plants have survived to date. Most of the willows and <br />cottonwoods have grown roughly 1.5 meters. <br />Lessons Learned: Although the site was planted only one year ago, it is obvious that a <br />thorough site evaluation is critical for revegetating sites with significant variations in <br />soil characteristics, water quality, and water availability. For example, the site <br />evaluation completed as part of this effort allowed relatively salt intolerant plants, such <br />as willow and cottonwoods, to be placed in areas where salt concentrations were within <br />tolerable ranges. Plants with greater tolerances to salinity, such as mesquite, were <br />planted in areas were salt concentrations were much greater. <br /> <br />Site #2 <br />No Name Lake <br />Location and Size: The 17 ha (41.S-acres) site is about one river km downstream from <br />Angnes Wilson Bridge and lies adjacent to farmland managed by the Colorado River <br />Indian Reservation. <br />Objective: To re-establish native riparian plants in an area where the rivers riparian <br />habitat has been severely compromised by agricultural activities. This project was also <br />part of a plan to mitigate damages caused by construction activities associated with the <br />Parker IT project <br />Completion Date: 1987 <br />Pre-Project Site Conditions: Prior to the revegetation effort, the vegetation on the site was <br />arrowweed, with some salt cedar, screwbean mesquite, and willow. The water table <br />depth was estimated to vary from 4 m on the upstream end of the site to about 1.S m on <br />the downstream end (Pinkney 1992). <br />Project Strategy: The site was cleared and root-ripped in April 1987. On-site, desirable <br />vegetation was not disturbed. A 38-cm (1S-inch) diameter auger was used to disrupt <br />the soil down to the saturated zone. Five days prior to planting, salts were leached by <br /> <br />Page 8 <br />