About NEMI

First launched in 2002, the National Environment Methods Index (NEMI) is a searchable database of environmental methods, protocols, statistical and analytical methods, and procedures that allows scientists and managers to find and compare methods for all stages of the monitoring process. Since its release, NEMI has been updated several times, each time to take advantage of better technology, accomodate new method types, or both.

Why was NEMI created?

Every year, U.S. federal and state government agencies, industrial entities, academic researchers, and private organizations expend enormous amounts of time and money for monitoring, protecting, and restoring water resources and watersheds. Similarly, large expenditures are made to analyze for toxic wastes, biological organisms, contaminants in ambient air, and other pollutants for which measurement data can help with environmental decision making.

Selecting appropriate analytical methods is a critical part of planning for monitoring projects and can be a complex project in itself. Methods must have sufficiently low detection levels, suitable precision and analyte recovery, and acceptable selectivity for a specific monitoring project’s needs; protocols for field data collection must meet minimum criteria for data quality objectives, etc.

Extended use of environmental data (for new projects or uses) is usually not considered when methods are selected. Yet, environmental data are often used again for other purposes, sometimes many years after publication. Whether extended use and interpretation of data generated over time (and by various agencies) are valid depends on whether the applied methods produced data that are comparable. Data comparability exists when data are of known quality and can be validly examined for potential use, even in some cases when project objectives differ. Data comparability minimizes duplication and maximizes the use of resources. Perhaps more importantly, data generated for one purpose may be prevented from being used for other purposes when data comparability shows that a method provided data that are not compatible with the needs of the second purpose.

Historical perspective

In the past, comparing the quality and suitability of environmental methods was difficult because there was no master list of substances and methods for their measurement. EPA’s Environmental Monitoring Methods Index (EMMI) grew out of a list of pesticides and other analytes routinely measured by what was then the Industrial Technology Division. Originally known as the “List of Lists”, this list of analytes and methods became EMMI. Between 1990 and 1995, EMMI was expanded to encompass all lists of analytes published in the Code of Federal Regulations plus lists of additional analytes of interest to EPA. The 1995 revision included ~4200 substances and 3600 method abstracts with information on various media such as water, soil, air, and tissues and, when available, detection limits. EMMI could be searched by synonym, apparatus, CAS number, and other useful fields. When EMMI was developed, fields were created for future inclusion of method performance information. Independently, the first database of EPA method summaries linked to lists of analytes was published in 1990 in three volumes on diskettes. An MS Windows version of EPA pesticide method summaries followed in 1995.

But even in 1995, no uniform standardized criteria existed in the world for comparing critical components of environmental analytical methods with each other or with a user’s project-specific needs. Instead, published methods typically focused on specific analytical objectives and ignored information that would allow users to assess whether data from one particular method will be comparable with data produced by other methods and project designs.

To address this problem, a multiagency Methods and Data Comparability Board (MDCB) developed NEMI, a major design component of which is to make comparisons of methods, and therefore the data generated from those methods, more straightforward. The MDCB is a partnership of water- quality experts from federal and state agencies, tribes, municipalities, industry, and private organizations. The National Water Quality Monitoring Council created MDCB in 1997 to coordinate and provide guidance on implementation of nationwide monitoring strategies. Although the focus of the MDCB guidance was on water methods, the need for comparability applies equally well to environmental analytical methods in all media and various analytes (e.g., chemical, radiological, macrobiological, and microbiological).

Method Submittal

We welcome all published/verified methods and protocols for inclusion in NEMI. We are always looking for new methods to be added to NEMI. These may include, for example:

  • methods for laboratory & in-situ analyses and monitoring
  • for field sampling/collection
  • in a variety of media/matrices (e.g. air, water, soil, sediment, tissues, etc.)

Government agencies, private companies, and public organizations (including commercial and volunteer monitoring sectors) may submit methods.

Forms have been developed to facilitate online submission of method information. Contact us for information to gain access to the online forms. Once you have sent us an email we will call you to answer any further questions that you may have and then you will be sent a form to be filled out with your method information.

Criteria for Submission of Method Information to NEMI   

Method information may be submitted by any public or private organization for consideration of inclusion in the NEMI database. Guidelines for acceptance include (1) documentation of method information in a manner such that it can be practiced by other scientists trained in a defined applicable field. This typically includes:

  • Documentation of applicable meta data such as percent recovery (or other forms of bias), precision, detection levels, concentration ranges, rates of false positive and false negative identifications, etc.
  • Factors that influence method performance such as interferences, required or recommended quality control and quality assurance procedures, sample preparation procedures such as concentration, dilution, digestions, sterilization procedures, culturing procedures, etc.
  • Method publication date and source reference information, applicable validation or verification procedures, lists of analytes or organisms, instrumentation requirements, etc.

and (2) public availability of the published full method by a governmental or private sector publisher. This includes methods that are associated with proprietary analytical instruments or equipment, copyrighted methods that are sold, and methods that support the determinative step (e.g., methods for sample collection, sample preparation, or in-situ analysis). Publication may be with a governmental or private sector publisher, and includes both printed and electronic formats. Methods that are published as research articles in journals or books are acceptable if procedures and performance are well documented, and there is evidence that the method has been successfully applied to a large number of environmental samples.

Submitted methods are reviewed for technical quality and applicability prior to being included in the database. A NEMI Review Committee has final authority for determining if a submitted method meets the criteria for addition to the NEMI database.

We welcome feedback and questions. To contact us send email to nemi@usgs.gov