南加州大都会水区（Metropolitan Water District of Southern California，大都会）一直在对加利福尼亚州项目水（SPW）、科罗拉多河水（CRW）以及这两种水的各种混合水进行评估，以便:模拟大都会根据第2步申请替代性能标准时所需的测试；并评估水质季节变化对TOC去除特性的影响。此外，这些数据用于评估确定收益递减点的最佳方法；数据通过“点对点”和曲线拟合方法进行分析（对测试水域使用三个曲线拟合方程）。总体结果表明，季节性水质变化确实会影响水对强化混凝处理的适应性；比紫外线吸收率（SUVA）表明了所测试混合物的可处理性； 对于水混合物是否适合强化混凝，点对点法和曲线拟合法得出了不同的结论；虽然没有一个方程能普遍适用于所有收集的数据，但三阶多项式方程比其他方程对更多数据集的统计拟合更好，而等值线方程在收益递减点的TOC去除率曲线比点对点法更一致。

The Metropolitan Water District of Southern California (Metropolitan) has been conducting evaluation on California State project water (SPW), Colorado River water (CRW), and various blends of the two waters in order to: simulate the testing that will be required if Metropolitan applies for alternative performance criteria under step 2; and evaluate the effects of seasonal changes in water quality on TOC removal characteristics. In addition, these data were used to evaluate the best means of determining the point of diminishing returns; the data were analyzed by the "point-to-point" and curvefitting methods (using three curvefitting equations for the waters tested). The overall results indicated that seasonal water quality changes do affect a water's amenability to treatment by enhanced coagulation; the specific ultraviolet absorbance (SUVA) provided an indication of the treatability of the blends tested; the point-to-point and curvefitting methods yielded different conclusions as to whether the water blend was amenable to enhanced coagulation; and although no one equation universally fit all the data collected, the third-order polynomial equation resulted in a better statistical fit to more data sets than the other equations examined, whereas the isopleth equation yielded curves with more consistent percentages of TOC removal at the point of diminishing returns when compared to the point-to-point method.