Some constituents of concern to water quality managers have very low water quality criteria. For example, EPA’s National Toxics Rule (NTR) criteria for arsenic, mercury, benzo(a)pyrene, and PCBs are 0.018, 0.14, 0.0028, and 0.000044 ìg/L, respectively (to protect human health based on consumption of water and organisms). These criteria are below the reporting limits that can be reliably achieved using typical sampling and analytical methods. Thus, water quality managers using typical sampling and contract analytical methods may have considerable uncertainty as to whether such constituents are actually present at levels that exceed criteria. To reduce such uncertainty, “ultra clean” sampling and analytical methods have been developed for some constituents, such as metals. However, ultra clean methods can be costly and difficult to apply in some field situations. This paper describes an alternative approach, wherein high-volume sampling and preconcentration techniques were used to achieve very low reporting limits for metals and organics. Two case studies are presented, one in a river tributary to Puget Sound and the other in the Columbia River.