Great Lakes Environmental Database
GLENDA Query System
Retrieve data from GLENDA
Guidance on specific formats for data submissions
Allowable Codes Tables
Tables of GLENDA-recognized codes
About the Great Lakes Environmental Database
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.
GLENDA was designed to include data from four
subject areas: project/organization, station/location, field monitoring
activities, and results.
- The project/organization subject area includes such information as
the name and description of the project, the contract, co-operative
agreement or grant that the data were collected under, the organization and
persons involved in the project along with their mailing addresses,
electronic addresses, and telephone numbers.
- The station/location subject area includes such information as the
name of the sampling station and its description, the latitude and longitude
of stations and any offsets or areas, the geopositioning technique and
accuracy, and names and codes of counties, states, and similar geographic
- The field monitoring activities subject area includes such
information as visits to stations for monitoring, any observations or
measurements taken during sampling or in the lab, and any remarks during field sampling
or lab activities.
- The results subject area includes such information as
analytical results, analytes, units of measure, correction factors, quality assurance
codes and flags, and any remarks on laboratory analyses.
There are three main types of tables in GLENDA
based on the type of information they contain: reference, static, and
- 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
- 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.