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Great Lakes Environmental Database (GLENDA)


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GLENDA Query System

Access GLENDA through EPA's Central Data Exchange (CDX). You will need to register and log in.

For questions about access please contact the CDX help desk.

For questions about the database, contact database manager Ken Klewin.

Related links

Lake Michigan Mass Balance 1994-2000 results

Limnology program

Great Lakes Indicators

Data categories

Subject Areas

simplified entity-relationship diagram for GLENDA

Table Types

There are three main types of tables in GLENDA based on the type of information they contain: reference, static, and dynamic. 


The Great Lakes National Program Office (GLNPO) collects environmental data on a wide variety of constituents in water, biota, sediment, and air.  Long after the studies are completed, the data remain and must be managed.

Central to the data management effort is a computerized relational database system to house Lake Michigan Mass Balance and other project results. That system, the Great Lakes Environmental Database (GLENDA), was developed to provide data entry, storage, access and analysis capabilities to meet the needs of mass balance modelers and other potential users of Great Lakes data.

Development of GLENDA began in 1993 with a logical model based on the modernized STORET concept and requirements analysis. This was followed in 1994-1995 with the development of field and laboratory reporting requirements, preliminary reference tables, and the initial creation of the physical tables. Recent years have seen the completion of the physical database and most reference tables, the creation of software tools to access the database, and the creation and use of upload routines to load Lake Michigan Mass Balance data.

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