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Technical Revision No. 80 <br />August 19, 1998 <br />Page 7 <br />when irrigation is not occurring. <br />To protect agricultural and municipal uses in the lower Colorado River Basin, Colorado <br />participates in the multi-state, basin-wide approach for managing salinity (TDS) in the <br />Colorado River. There are no Colorado stream standards for TDS based on stream <br />classifications. TDS is controlled to maintain the following flow-weighted annual values <br />for TDS: Below Hoover Dam: 723, mg/L; below Parker Dam: 747 mg/L; at Imperial <br />Dam: 879 mg/L. The Colorado regulation recognizes that periodic increases above the <br />criteria are in conformance with the standards, provided that, when conditions return to <br />normal, concentrations are expected to be at or below the criteria level. <br />The normal range for TDS in irrigation water is between 0 to 2000 mg/L. Continued acrd <br />prolonged irrigation with water having a TDS concentration between 500 mg/L and 2000 <br />mg/L may impose slight to moderate requirements for management practices (leaching and <br />drainage) or crop selection (use of less sensitive crops) in order to avoid crop yield <br />reductions. Because crops are affected only when TDS in root-zone water builds up to <br />excessive levels, occasional excursions of TDS in irrigation water above 500 mg/L are <br />generally not significant, as long as the average annual value is lower. <br />Groundwater Quality <br />43. Please check the data entered tnlo Table 54 of your TR-80 submittal for accuracy. The <br />data do not correlate precisely with baselrne data presented irr previous AHRr. Please <br />jootrrote Table 54 to indicate that the data are baseline. Provide a revised Table 54. <br />Table 54 has been reviewed and compared to the values presented in the 1996 Annual <br />Hydrology report. The table has been revised accordingly and is enclosed. <br />Additional General Comments <br />No remaining issues in this section. <br />Please find enclosed a file memorandum by William Lorah of WWE that summarizes his <br />conversation with Chuck Roberts of the Division of Water Resources regarding the issues raised <br />by the State Engineer's Office in a letter to CDMG dated August 14, 1997. MCC submitted an <br />application to Colorado Water Court for a North Fork Augmentation Plan in December 1997. <br />In addition, the following are MCC's responses to Mr. Stover's letter of October 10, 1997. <br />1. MCC presents some interesting timing data that was previously unknown to Bear. MCC's <br />INW-SNW longwall panels were sealed irr May of 1995. The sealed panels created the NW <br />Sealed Sump. Until May ojl995 the small capacity sumps located in the longwall panels, <br />up-dtp and adjacent to the Bear No. 3 Mine were routinely dewatered. Once these panels <br />