EPA collects environmental data on a wide variety of constituents in water, biota, sediment, and air.  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.

Data Categories

• Water Quality Survey Chemistry
• Fish Tissue Chemistry
• Fish Sample Information
• Lake Michigan Mass Balance Projects Data
• Sediment Chemistry (limited)

Subject Areas

• project/organization
• station/location
• field monitoring activities
• results

Table Types

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

• Reference tables primarily include lists of reference-type information such as lists of allowable codes or units that can be referred to by other tables. Examples are laboratory and field remark codes, quality control codes, units of measure, analytes, and so forth. These tables are supplied by GLNPO and are fixed, with additions being rare.
• Static tables include information about projects, organizations and people, sampling stations and their locations, and so forth. These data are supplied by users or participants on an as-needed basis when a new project is undertaken.
• Dynamic tables include information on samples and results, including field and laboratory data. These data are supplied by users or participants whenever new sampling and analyses are undertaken.