Laserfiche WebLink
<br />Developing Salinity Control Targets <br /> <br />return flows be completed before control measures, temporary increases <br />above tij,e criteria could result, and these will be in conformance with the <br />regulation, With completion of control projects now in the plan or those to <br />be added. subsequently, salinity would return to or below the criteria level. <br /> <br />ru <br />CJl <br /><:) <br /><:) <br /> <br />The goa~ of the Colorado River Basin Salinity Control Program is to <br />maintaip. the flow-weighted average annual salinity at or below the numeric <br />criteria of the salinity standards, The salinity control program is not, <br />however:, intended to counteract the salinity fluctuations that are a result of <br />highly v~riable flows caused by climatic conditions, precipitation, snowmelt, <br />and othtr natural factors. Therefore, to evaluate the effectiveness of the <br />salinity control program, water quality data are adjusted using a computer <br />model to normalize the data so that they reflect average hydrologic <br />conditions, <br /> <br />Figure 2 compares the normalized <br />salinity to the numeric <br />criteria at Imperial Dam. <br />This is a computer generated <br />comparison which removes <br />hydrologic variations from <br />the observed salinity, <br />Reclamation first runs a <br />computer model of the river <br />to confir):n that the model is <br />accurately re-creating <br />historic salinity levels <br />observed in the river system, <br />Next, th~ entire range of <br />flows (1906-present) is run <br />for a paxjticular year (or level <br />of wateridevelopment). This <br />produce~ a flow-weighted <br />average annual salinity for <br />that particular year, This <br />average 1s then compared to the <br />numeric :criteria of the standards. <br /> <br />1100 <br /> <br />1000 <br /> <br />iooo <br />~ooo <br />;jJ <br /> <br />numeric criteria. 879 mgIL <br /> <br />.... ,..... ,..............-.--...-- ----- -.---..-........... <br />/"~---'_._---.............//---------._---,/--_._-.. <br /> <br />Salinity adjusted to average <br />flow conditlons for <br />comparison to the numeric <br />criteria of tha salinity <br />standartls, <br /> <br />1975 1980 1985 1990 <br /> <br />700 <br /> <br />800] <br />1965 <br /> <br />1970 <br /> <br />Figure 2,-Normalized or "flow-adjusted <br />"salinity at Imperial Dam. <br /> <br />Reclamation updates this evaluation periodically to assess whether current <br />salinity control projects are sufficient to meet the numeric criteria of the <br />salinity $tandards, Figure 2 summarizes the results of this analysis over <br />the past;25 years. The figure shows that the numeric criteria of the <br />standards have been consistently met, The salinity control program has <br />offset the effects of future water development in compliance with the <br />standards. <br /> <br />l <br /> <br />21 <br /> <br />'."~'.L <br /> <br />Ai. _;"'k--.,-. <br /> <br />~,-j <br />+~- <br />