Dreamflows Alerts
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All About Alerts


There are two broad classes of alert - Bulletin Board Alerts, and Flow Alerts. 

Bulletin Board Alerts send you email when new messages are posted to the bulletin board.  The principal intended use is to alert you when a new hazard is posted to the bulletin board, though you can control which flow sites and which forums you receive alerts for.

Flow Alerts send you an alert when the flows on rivers of your choice rise above, and/or fall below, levels which you set.

When Dreamflows sends you an alert of either class, it does so by creating a regular (but very short) email message and sending it to your Pager Address as set in your profile.  If you sign up for Dreamflows Alerts, be sure to set Pager Address to the correct address.  Also, check that your Alerts Status is set to Active.  If you have an alphanumeric pager, then Pager Address is the email address assigned to your pager by your paging company.  If you don't have an alphanumeric pager, then Pager Address may be any email address of your choosing, although one option is to make it the same as your regular Email Address.  If you leave the Pager Address field in your profile blank, then your pages are sent to the Email Address by default.

Bulletin Board Alerts

Bulletin Board Alerts send you email when new messages are posted to the bulletin board.  You have some control over when you receive such alerts.  In essence, you can choose between receiving them for specific flow sites, or for all flow sites in a given set of regions (a region is currently a State).  You can also select which forum(s) you are interested in posts for - by default the Hazards forum is selected, but you could add Flows, Access or even General.  See the setup help page for details on exact setup options available to you.

Flow Alerts

Dreamflows flow alerts are designed to send you an alert each time the flow on a river of your choice rises above, and/or falls below, minimum and maximum values.  The idea is to inform you when your favorite rivers are running, or perhaps when some rivers you're having a hard time catching at the right flow start running.  You have a great deal of control over when and how the alerts are generated, as follows:
  • You select which rivers you want alerts generated for.

  • You select on which days of the week you want Dreamflows to generate alerts, for the rivers you selected.

  • On each day of the week you select, you specify Start-Time and End-Time, i.e. the period of time during which you want alerts to be generated.

  • For each river which you select, you specify minimum and/or maximum flows of interest, and various other parameters which allow you to control when alerts are generated.
  • Alerts are generated at the same time as the Realtime reports are run.  It usually takes a couple of minutes for the process to complete, so alerts are typically generated at about 22 and 52 minutes past the hour during the day (e.g. 7:22am and 7:52am), and about 52 minutes past the hour at night (e.g. 7:52pm).  How long it takes the alert to reach you depends on Internet access speed, and the efficiency of your ISP or paging service.

    There are two types of flow alert: Normal and Continuous.  In each, there is the concept of Good flow (i.e. the flow is between the minimum and maximum flows of interest that you set), and Bad flow (i.e. the flow is below minimum or above maximum).

    With Normal alerts, you receive alerts between Start-Time and End-Time only when the flow transitions from Bad to Good, or from Good to Bad.  This type of alert is intended for the paddler who primarily wants to be notified when a river of interest is running, (i.e. is at Good flow).

    With Continuous alerts, you also receive alerts between Start-Time and End-Time when the flow transitions from Bad to Good, or from Good to Bad.  However, in addition, you will receive alerts (between Start-Time and End-Time) each time Dreamflows runs and the flow is Good.  This type of alert is intended for the paddler who wants to continuously monitor the state of a river (for example, wants to receive alerts while on the way to the river, or even while running the river).  Needless to say, if set up carelessly, this type of alert can easily result in more alerts than you bargained for.

    The easiest way to find out more about how alerts work is to try an Alerts demo.  This simulates setting up Normal alerts of your choice, without actually saving any of the data.

    The best way to stop receiving alerts altogether (e.g. it's the wrong time of year or you're going on vacation), is to disable them by visiting your profile, and setting Alerts Status to Inactive/Vacation Hold.  Alternatively, click on Normal Setup or Continuous Setup in the gray menubar, as appropriate, click Continue, and disable individual flow sites.  Either strategy allows you to leave inactive flow sites on the system, pre-configured for the next time you want to start receiving them.


    You will need a Dreamflows account.  If you don't have an account, signup for one.  If you want to be paged, you will in addition need an alphanumeric pager of the kind that will accept pages from your Pager Address.  Numeric pagers that must be paged from a telephone are not supported.  If you don't have an alphanumeric pager that's okay - you can just ask for your alerts to be sent to a regular email address (but note that helping you configure your computer to automatically fetch new mail is not part of the Dreamflows Alerts service). 

    Limits and Limitations

    The important thing to realize is that there are delays every step of the way, and so your flow alerts are bound to be delayed to some extent.  Specifically:
  • A typical river gauge doesn't measure flow continuously.  Rather, it measures flow at intervals.  The majority of gauges measure at 15-minute intervals, but some measure only every hour, others even less frequently.

  • A typical river gauge doesn't send its measurements to the controlling agency (e.g. CDEC or USGS) immediately.  Most gauges send their data "home" via satellite, and they can do that only at certain times, or under certain conditions.  Even then, sometimes transmission fails and the data is delayed until the next time slot, or perhaps even lost altogether.

  • Dreamflows doesn't poll agencies continuously, but rather does so every 30 minutes during the day, and every hour during the night.  In addition, there can be delays in getting raw flow data to Dreamflows, or sending you an alert, because of Internet access problems.

  • Due to scheduling delays and technical difficulties, your paging company may take several hours to deliver your page.

    The good news is that, in general, these delays usually aren't severe, and most of the time, for most rivers, you can reasonably expect to get your alert an hour or two after the river comes up (or goes down, or whatever it does to generate an alert).  However, as you can see from the above, there is no guarantee that will you receive an alert in a timely manner, or even that you will receive one at all.

    Alerts can be sent to only one Pager Address.  If you want alerts sent to multiple addresses, please signup and create multiple Dreamflows accounts.


    Dreamflows Flow Alerts could be sent to you in error (e.g. because a gauge is malfunctioning, or has a temporary glitch).  Also, since alerts are delayed, the flow will almost certainly have changed by the time you get the alert, and will have changed once more by the time you put on the river.  This can be especially true of dam-release rivers, or after a rain storm - but it can happen any time.  Therefore, be sure to use Dreamflows Alerts as just another source of river flow information, not as instructions (or even suggestions) to go run a given river.  Rather, use the alert as a trigger to start your own research into whether or not to go run the river in question.  In any event, when you get to the river, verify for yourself that there is enough water - but not too much - before deciding to put on.