Monitoring agencies throughout the northwest are increasingly adopting the principles of survey sampling to design stream monitoring networks to track the status and trends in resource condition (stream habitat and chemistry, biota, riparian condition) for biological assessments or effectiveness of strategies.  In survey sampling, sites are selected from a representation of the relevant stream networks (e.g., digital hydrographic traces) by incorporating randomization in the site selection process.  Several algorithms have been developed that allow a user to select sites that meet their design requirements.  An algorithm (called a generalized random-tessellation stratified design, GRTS) is increasingly being used to generate a spatially-balanced set of sites (see Stevens and Olsen (2004) and Dobbie et al. (2008) for details about the advantages of a spatially-balanced sample compared with simple random or systematic samples).  One consequence of the increasing interest in using GRTS is that a variety of spatially-balanced designs are being developed in overlapping geographic domains according to each users specific interests.  There is potential for redundancy, non-optimal designs, and lack of communication among agencies with overlapping responsibilities.  To alleviate the potential for this type of problem and to facilitate the integration of the designs during the design process, the concept of a master sample has been developed and applied to stream networks in the NW (Larsen, et al., 2008).  

A master sample is a full list of sites that could be potentially sampled, structured so that a user could select a subset from the full list and retain the principle of randomization and spatial balance in the subset of sites selected (see Larsen, et al., 2008).  Statewide master samples covering stream networks in Oregon, Washington, and Idaho have been developed.

The Pacific Northwest Aquatic Monitoring Partnership (PNAMP) is developing an Integrated Status and Trends Monitoring (ISTM) project to demonstrate the concept in the Lower Columbia region.  It is anticipated that the PNAMP ISTM project will increase familiarity with the concept and use of a master sample. As part of the ISTM effort, PNAMP is proposing to develop a prototype web-based master sample tracking and management system to support the interests of increasing numbers of users in drawing samples from the same population domain. In conjunction with the development and use of the web-based master sample management tool, there is a need for dedicated analytical support for design and utilization of results of the monitoring design based on the master sample. This project will develop a prototype master sample management tool using the Lower Columbia region as a demonstration area and to provide the necessary statistical support.  The Lower Columbia was selected as a demonstration area because it is a manageable size, several monitoring programs using GRTS designs on stream networks in the Lower Columbia are already in place, and an example area-based sample of the Lower Columbia estuary was selected by the USEPA in 2007.  This project will develop the prototype Master Sample Management System, make it available to users, and provide statistical design and analysis support for the two years of the project. This system will be developed so that it is readily expandable to more extensive regions, e.g., to the entire Pacific Northwest.