Low Resource Warning
Mod adds an alert that fires any time a resource deposit falls below 300 units.
Notification is fully featured, indicating what resource, clicking on it will take you there, and once dismissed will never reappear. If more than one resource falls below the threshold simultaneously, clicking will cycle between and a slightly different message will appear.
Mod is configurable. Browse to %appdata%\Surviving Mars\LowResourceAlerts and open the config in any text editor. By default concrete is not notified, all other resources are. Notification threshold is also configurable, although any resource deposit that starts with less than half this value will be ignored and never throw a notification.