1997 AGN APR 01 I29 - Laserfiche WebLink

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Ground water extraction from the Colton -Rialto Basin comes from two wells located in an area known as La Sierra, one well located in the Lytle Creek Channel area, and two in the Cooley Ranch area provide, approximately 20% of Colton's water. Ground water extractions for the North Riverside Basin comes from one well, which provides for 10% of Colton's water. Ground water extractions from the Bunker Hill Basin comes from 9 wells; five of these wells are located in the Rialto well field, and four are located Walnut well field. Extractions from the Bunker Hill Basin supply approximately 70% Colton's water. The present water supply is being threatened on two fronts. The first is the general lowering of water levels in the Colton -Rialto Basin (which is an adjudicated basin). Although this is a significant threat to current water supplies, it is relatively predictable and, therefore, allows for advance planning for replacement supplies. The second and most significant and unpredictable threat to water supplies is volatile organic compound VOC contamination in the Bunker Hill Basin. The majority of the City's well production is situated downgradient from known plumes of VOC contamination. It is not known when or to what extent these plumes will impact City wells. 2. Future Water Supplies The Feasibility Study of Supplemental Water Supply Alternatives for the City of Colton presents two scenarios for providing additional water supplies. Scenario "A" assumes that the Bunker Hill Basin well fields are not affected by the VOC plumes or, if affected, that contamination levels are below allowable limits. Scenario "B" assumes that VOC contamination occurs and that contamination is above the allowable limits for potable water. The following is a summary of additional supply alternatives in each scenario: Scenario "A" - No VOC Contamination Develop additional wells in the Bunker Hill and North Riverside Basins; 1) Connect to the San Bernardino Valley Municipal Water District's (SBVMWD) Baseline Feeder; 2) Construct a City of Colton Water Treatment Plant at the Rialto well field site to receive and treat imported water from the State Water Project from an existing turnout off the Santa Ana Pipeline; 3) and Construct, in partnership with the City of San Bernardino, a regional water treatment plant at Devils Canyon to treat State Water Project water.