Dreamflows Frequently Asked Questions
 
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  1. Which flow sites are reported by Dreamflows?
  2. Where do I find the most recent flow value for 'River X - At Place Y' as reported by Dreamflows?
  3. The flow site 'River X - At Place Y' used to appear on the Dreamflows flow reports.  Why can't I find it now?
  4. The flow site 'River X - At Place Y' doesn't appear to be reported by Dreamflows at all.  Why not?
  5. Dreamflows reports flows for site 'River X - At Place Y'.  What is the corresponding gauge location?
  6. How are reservoir inflows calculated, and why do they bounce around so much?
  7. How does Dreamflows go about estimating the flow at a site for which there is no gauge?
  8. On the Tuolumne, why was the inflow to Don Pedro Reservoir less than the flow at Meral's Pool today, even though Don Pedro is far downstream?
  9. I'm currently subscribed to Email Reports (i.e. Dreamflows daily flow reports via email).  How do I unsubscribe?
  10. How do I determine what Dreamflows flow site(s) to use for a given river reach/run?
  11. I'm a paddler and have hazard (or whatever) information to share.  Why won't the Dreamflows Admin post this information on the bulletin board for me?

     
  1. Q: Which flow sites are reported by Dreamflows?

    A: Check out the appropriate Cross-Listing page (each page lists every flow site supported by Dreamflows for that state, along with precise gauge location information, and a list of runs served by that site).  To see which flow sites have been added recently, check the Changes page.
     

  2. Q: Where do I find the most recent flow value for 'River X - At Place Y' as reported by Dreamflows?

    A: If the flow site is in California or Nevada, try the Realtime flow report first.  If not there or the site is not in CA/NV, check the appropriate Daily flows report.  If you still don't find the flow and there's a corresponding blue link on the report (i.e. under the Location name), click on that and you will be presented with a graph of recent flows.
     

  3. Q: The flow site 'River X - At Place Y' used to appear on the Dreamflows flow reports.  Why can't I find it now?

    A: The Realtime flow report lists only those CA/NV flow sites which are capable of providing realtime data, so be sure to check the most recent Daily flow report too.  On rare occasions Dreamflows stops reporting a site altogether because the gauge site for it is no longer reported online.  See question #1 for a list of flow sites reported by Dreamflows.  To see which sites have been removed recently, check the Changes page.
     

  4. Q: The flow site 'River X - At Place Y' doesn't appear to be reported by Dreamflows at all.  Why not?

    A: In order for Dreamflows to report flows at a flow site, it needs to know the flow, or at least be able to compute or estimate it.  If suitable flow information is available online and you'd like to see the site reported by Dreamflows, please contact chris@dreamflows.com and tell me about it.  If no suitable flow information is available online, then it's still possible that flow information may be available by other means.  Several paddlers help Dreamflows (and therefore all of us) by gathering information by phone and entering it into Dreamflows via a special web page.  Others drive by a gauge that isn't on the web and enter the information into Dreamflows (also via a special web page).  If you have access to flow information not available online, please contact chris@dreamflows.com so everyone can share.
     

  5. Q: Dreamflows reports flows for site 'River X - At Place Y'.  What is the corresponding gauge location?

    A: Gauge location information is available for every flow site reported by Dreamflows.  To access it: go to the appropriate flow report, locate the flow site of interest, and click on the brown link (i.e. the River Name column).  Alternatively, go to the appropriate Cross-Listing page and search for the site of interest.  Either way, gauge location information appears just below the name of the flow site.  Click on the icon for a map of the gauge location.
     

  6. Q: How are reservoir inflows calculated, and why do they bounce around so much?

    A: The inflow is the total inflow calculated by taking the change in storage since the last measurement, converting it to an average CFS equivalent, and adding outflow.  Storage is determined by measuring elevation of the water in the reservoir, usually at or close to the dam.  On your typical reservoir, even a 1/10" error in measuring elevation translates to a large error in calculated storage - because that's 1/10" of water spread over many square miles.  Consequently, calculating inflow in this way over short intervals (like an hour) is inaccurate.  The result is that the calculated inflow usually bounces around a lot, even when the actual inflow is constant.

    It's hard to make out what's happening when inflow appears to be bouncing around like that, and over longer periods of time the errors are reduced.  So, sometimes average inflow is reported as well.  This is just inflow, but averaged over several intervals - six, say. 

    Although often useful, these methods are imperfect: inflow by itself jumps around like a yo-yo, while average inflow smooths out not only the yo-yo effect, but legitimate changes as well.  Note also that inflow measures total inflow to the reservoir, which includes all side-streams and precipitation.
     

  7. Q: How does Dreamflows go about estimating the flow at a site for which there is no gauge?

    A: The most common method that Dreamflows uses is to go through the historical record, and create a model which predictably describes the relationship between the flow site with no gauge, and another flow site which does have a gauge.  For example, the USGS operated a gauge on the South Fork Smith for several years, but doesn't any more.  Conversely, the USGS currently operates a gauge at Jedediah Smith State Park on the Smith River, and has done for many years.  Historical data for both these gauges is available.  Statistical analysis of this data indicates that, for the month of January, on average, the flow on the South Fork Smith is 45% of the flow at Jedediah Smith State Park.  The analysis also shows that this relationship is pleasingly consistent, i.e. while the percentage usually isn't exactly 45%, it's almost always acceptably close.  So, for January, Dreamflows estimates the flow on the South Fork Smith as being 45% of the flow at Jedediah Smith State Park.  Dreamflows allows for flow travel time in its calculations (i.e. it estimates how long it takes water to travel from the historical South Fork gauge to the actual Jed Smith gauge).

    Other methods include:


     
  8. Q: On the Tuolumne, why was the inflow to Don Pedro Reservoir less than the flow at Meral's Pool today, even though Don Pedro is far downstream?

    A: Dreamflows reports the average inflow to Don Pedro, and the instantaneous (usually 1pm) flow at Meral's, so comparing the two is like comparing apples to oranges.  After adjusting for flow travel time, and assuming no gauge errors, the Meral's Pool flow will always be less than the Don Pedro inflow.  However, the Meral's Pool flow normally fluctuates with powerhouse cycles (and, depending on the season, rain and snowmelt cycles too).  On the other hand, the reported Don Pedro inflow is a steady value with all those fluctuations smoothed out.  So, the instantaneous Meral's Pool 1pm flow will quite likely be significantly higher than the average Don Pedro inflow, even though the average Meral's Pool flow is less.
     

  9. Q: I'm currently subscribed to Email Reports (i.e. Dreamflows daily flow reports via email).  How do I unsubscribe?

    A: There are instructions in the Helpful Dreamflows Links section of every report sent to you.  They will direct you to your profile, where you can set the Reports Status to Inactive/Vacation Hold.
     

  10. Q: How do I determine what Dreamflows flow site(s) to use for a given river reach/run?

    A: Visit the Alphabetical List of rivers and river reaches supported by Dreamflows flow sites.  The list will not only help you determine which flow site(s) serve your favorite runs, it also shows the most recent flow and provides links to other Dreamflows pages giving more detailed information.
     

  11. Q: I'm a paddler and have hazard (or whatever) information to share.  Why won't the Dreamflows Admin post this information on the bulletin board for me?

    A: The Dreamflows Admin is more than happy to post river-related information when it's provided by government agencies or water and power utilities.  However, the Admin doesn't have the time to post messages on behalf of private paddlers, so if you're a paddler please post anything of interest yourself - particularly information about river hazards, flows, or access.


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This page was last updated Wed, Nov 22, 2017.