Whatever the final answer to the water crisis may be, it is evident that within the High Plains, irrigation water will never again be the abundant, inexpensive resource it was during the agricultural boom years of the mid-twentieth century.
不管水资源危机最终如何解决,高原上的灌溉用水资源再也不会像这里20世纪中叶农业景气年份那样充裕、廉价了.——按我翻译的就可以了.
问题1：我反问一下,be+形容词有问题吗?没有是吧?那把你原来问句的状语will never again去掉,再看看.不要把习惯当成准则,也不要把2个词的搭配扩大到N个词.
问题2：前面是省略了成分.非要补全的话,加that或as都可以.