Integrated Status and Trends Monitoring (ISTM) Master Sample Component

A key objective of the ISTM project is to apply a region-wide “master sample” concept to the selection of sampling locations in the Lower Columbia river area. Using a probabilistic-based approach to monitoring design will support the integration of monitoring results across programs.

The need for aquatic resource condition surveys at scales that are too extensive to census has increased in recent years. Statistically designed sample surveys are intended to meet this need. Simple or stratified random sampling or systematic survey designs are often used to obtain a representative set of sites for data collection. However, such designs have limitations when applied to spatially distributed natural resources, like stream networks. Stevens and Olsen proposed a design that overcomes the key limitations of simple, stratified random or systematic designs by selecting a spatially balanced sample. The outcome of a spatially balanced sample is an ordered list of sampling locations with spatial distribution that balances the advantages of simple or stratified random samples or systematic samples. This approach can be used to select a sample of sites for particular studies to meet specific objectives. This approach can also be used to select a “master sample” from which subsamples can be drawn for particular needs. At the same time, these individual samples can be incorporated into a broader design that facilitates integrated monitoring and data sharing.

As part of the ISTM effort, PNAMP (working with Oregon State University) developed a prototype web-based master sample tracking and management system tool to support the interests of increasing numbers of users in drawing samples from the population domain. The intent was to allow users to know who else has selected sites from the master sample covering stream networks in their domains; to design individual or integrated monitoring programs; to know how existing sites relate to a common master sample; and what they are collecting at the site over time. The prototype was applicable only to the ISTM demonstration area of the the Lower Columbia River region. Since the development of the prototype tool, PNAMP decided to pursue additional development to convert the prototype into a production-level, regional resource that can support the interests of increasing numbers of users in drawing samples from this population domain. In conjunction with the development and use of a web-based master sample management tool, we understand there is a need for dedicated analytical support for design and utilization of results of the monitoring design based on master sample. This support is currently provided on an as needed basis. 

For more information about this past project or specific events related to this project, please contact us at gs-pnamp_contact@usgs.gov.