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o (',;,) Co\) !of", BASIC STUDIES available for the ten years 1955-1964 covering the development period. The amount of dissolved solids (as measured in Big Sandy Creek) picked up from project lands has varied considerably over the years, being high the Yirst four years, low the next four years, and slightly higher the last two years. There has also been a variation in the number of acres irri- gated, in the available water supply, and in the dissolved-solids increases as new land is brought under irrigation. Leaching of the more soluble salts from newly irrigated land takes place rapidly. As time passes the amount of material leached decreases until a balance is achieved between salt build- up and leaching rates. For example, during the 4 years 1958 through 1961 irrigated acreage was relatively constant. If, during the first two years, it is assumed that initial leaching was taking place, then the last two years may represent the normal dissolved-solids pickup of about 2.2 tons per acre for these irrigated lands. This pickup may be low J however, because during both 1960 and 1961 only a little runoff was available to flush accumulated salts into Big Sandy Creek. The results of this study, shown in the accompanying table, involve some compl-ications. Drainage from some of the irrigated land does not reach Big Sandy Creek but is consumed by nonbeneficial vegetation. Same losses in return flow occur between the irrigated area and the measuring point on Big Sand Creek. The measured pickup of salts from the irrigated land would undoubtedly be greater if the total amount of return flow were included. The Eden project has had poor drainage which has resulted in salt accumulation. The construction of drains relieved this situation and caused the accumulated soluble salts to leach into the streams. The values by years for the ten-year period are tabulated on page 24. Collection of data should be continued for a few years during which acreages ~rrigated are relatively constant to further determine the trend in salt pickup and whether possible errors in quality or flow measurements have unduly influenced the conclusions. 2. Florida Project Construction of the Florida project was completed in 1965. The Lemon Reservoir on Florida River regulates the flow of the river for irrigation of 19,450 acres of land including 5,730 acres not previously irrigated and 13,720 acres in need of supplemental water. In order to obtain quality information under preproject conditions, flow and quality data were collected at several points in the Florida project area beginning in 1958. A study has been made of these data for the period 1958-1962 to show the effect that irrigation of these lands has on the quality of return flows leaving the project under the condition of no storage. For comparision, another study will be undertaken begin~ ning about 1969 to reflect project conditions during storage. 25