Laserfiche WebLink
Mr. Midua' Brnl(ay/Ms. Sxdrr~ • <br />Division of Mcter'ats aril Gmtpg~ <br />SeptarJxi~29, 1999 <br />Pale 8 <br />New reservoir construction would require a full engineering evaluation and engineered fill <br />placement. Under current regulations, the cost to engineer and rebuild the reservoir would be <br />significant. In addition, SCC now holds ]5/16 the of the water rights for the reservoir. Since <br />those water rights are used for the Yoast Mine water rights augmentation plan, SCC has no <br />intention in transfeaing those rights back to the Sage Creek Reservoir, or any other potential <br />reservoir on Sage Creek. <br />Chr 6/15/99, Dennis Jones (SCC Hydrologist) had a conversation with Mr. John Ricks, the <br />current owner of the Sage Creek Reservoir site. Mr. Ricks, once again stated that he does not <br />want the reservoir to be reconstructed. He stated that his plans were to eventually sell this land as <br />potential homesites. 71~is irdirates that t1x r~abiliry for dx fuurm imgariaz n/b~ecT area in Sertian 30, <br />T6N, RS7Wdaes notexzst! <br />The subject area in Section 30, T6N, R87W is currently a wheat field. According to the CMLRD <br />1988 AVF Guidance Document, the threshold irrigation wazer conductance value for wheat is 4.0 <br />nunhos/cm. This is significantly higher that the 2.9 mmhos/cm maximum value predicted by <br />SCC to occur in Sage Creek as a result of Yoast Mine discharges. Also, this wheat field is not <br />being imgated, nor will it be given that the Sage Creek Reservoir will not be rebuilt. <br />Crop-reduction calculations tabulated for the salinity tolerant plant species listed (wheatgrass, barley <br />and perennial ryegrass) are shown in Table 7.1, Crop Reduction Estimates for Salirtiry Tolerant Crop <br />Species. The salinity threshold for these crops (from 3.7 to 5.0 mmhos/cm) is well above the <br />potential projected maximum salinity increase to Sage Creek (2.9 mmhos/cm). Therefore, these crops <br />will not be adversely affected by the projected TDS alteration to Sage Creek, as shown by the negative <br />crop reduction percentages in Table 7.1, Crop Reduction Estimates for Salinity Tolerant Crop <br />Species. Per Banta (1988), salinity threshold values for moderately tolerant crops range from 2.0 to <br />4.0 nunhos/cm, and from 4.0 to 6.5 mmhos/cm for tolerant crops. Therefore, many species of <br />moderately tolerant and all species of tolerant crops could be irrigated with post-mining surface water <br />from Sage Creek with no adverse impact to crop yields. <br />TABLE 7.1, CROP REDUCTION ESTIMATES <br />FOR SALINITY TOLERANT CROP SPECIES <br />1Fie/d in Secflan 30. TBN, RBTWI <br />Yieltl Predicted Salinity Relative <br />Decrease Conductivity Threshold Yieltl Crop <br />Bw Ecw Aw Y Reduction <br />(percent) (mmhos/cml (mmhos/cml (percent) (Percent) <br />Lune Whestgress lFeirweY Crosfed Wheefg~ess (Agropyron cdafetumll /flyers and Wesmot, 19851 <br />10.0 2.9 5.0 121.0 -21.0 <br />Highcrested Wheetgrsss (Tall Wheetgrsss (Agropyron a/onpetum/1 (Ayers and Wesrcot, ]9851 <br />6.25 2.9 5.0 113.1 -13.1 <br />5.40 2.9 5.0 111.3 11.3 <br />Porannie/ Ryegrass (La/rum peronrre/ (Ayers and Werrcot, 19851 <br />10.7 2.9 3.7 108.6 -8.fi <br />PROJECTED TOTAL REDUCTION FOR PASTURE <br /> Tp: -13.5 <br />Notes: ew =percent yie/0 decrease per unit salinity increase <br /> Ecw =Predicted speci/ic conductance of irrigation wafer <br /> Aw =Salinity threshold of irrigation water <br /> 7R =Projected tote/ reduction in crop yie/ds based on each crop species <br /> representing 25 percent of the (oral lie/d makeup <br /> Relevances: Banta !19881, Ayers and Wesrcot (19851 <br />