The main application window. Only one instance of this window is opened and it is available until the application exits. User access to all other functionality in this application is available through controls on the main window.

Before any other functions can be used, a site must be specified by clicking the 'Specify Site' button and selecting an agency code and site id. The 'Check' button will display the site name if it can be found. Using the 'Check' button is optional, the 'Ok' button also verified that the specified site can be found in the database.

Most functions also require the selection of data descriptors. The lists of available descriptors for flow and stage are populated when a site is specified.

Specifying time is important to all functions. If the default of the most recently ended water year is not desired, click the 'Specify Time' button.

When specifying time, several date formats are available. Dates can be specified by 4-digit water year or calendar year or by a date formatted YYYY-MM-DD. Special-purpose formats are also available for specifying all the dates of the available peaks, daily values, or unit values. Selecting one of these formats will cause a brief pause while the database is accessed and the desired dates are found. Selecting 'All Available Dates' sets extreme values for the starting and ending date. This effectively removes date as a criteria by making sure that any date is between the start and end.

Buttons may be available for viewing unit and daily values

The 'View Peaks' button retrieves peak flow and stage information from the database.

The 'End-of-Year Summary' button will compute and display a report if a year of available data has been specified.

The 'Run PeakFQ' button may be available if PeakFQ has been installed.

A status label at the bottom of the window displays the user id, access level, and sometimes a message about what PeakFlow is currently doing.