Water Management (Sharing Shortages) In California In the Short and Long Term, Part 1

san_diego_sdskyline14_smCalifornia surface water and groundwater laws are increasing controls rapidly, and the changes aren’t over yet.  The end result will likecreek_through_meadow_smallly be that shortages in San Diego will reduce how much a license holder in Modoc County can take.  It will probably take 20 years for the full effect…but 20 years is a lot faster than it used to be for farmers, ranchers, cities, and the environment.

How does this work?  It is harder to see from the surface water side.  How are the two ends of the State even connected, hydrologically?  Some diverters up around Alturas divert from the Pit River, which flows into Shasta Lake on the Sacramento River, which flows to the Delta, from which water is pumped by the U.S. Bureau of Reclamation (USBR) and the California Department of Water Resources (DWR).  Actually, DWR diverts water released from Lake Oroville on the Feather River, but that water joins the Sacramento River at Verona, before it gets to the Delta.Central_valley_project-01_wiki

The federal water goes to the San Joaquin Valley, which is the southern end of the Great Central Valley and salad bowl of California.  The USBR Central Valley Project (CVP) coordinates to some extent with the California State Water Project (SWP).

CVP_State_water_project_wiki

 

 

 

The state water goes partly to the San Joaquin Valley, and mostly over the Tehachapi Range to the Los Angeles Basin.  Where the water goes from the CVP and SWP is carefully controlled by water rights and contracts.

 

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What we don’t see with our own eyes is the groundwater picture.  Groundwater pumping has dramatically increased during the last few years of drought, as news articles have made clear.  Nobody’s groundwater rights are affected by the new groundwater laws, but every groundwater basin either has or will soon have a local management agency of some type.  Maps of groundwater shortages will be in news articles, online, and where every citizen of California can see them.  This is part 1 of a several-part post on how in the world, or in this case the state, groundwater shortages in the extreme South will affect surface water diversions way up in the North.

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Update to “Weirs – Planning, Building, & Measuring Flows”

This is an update and correction to the December 24 post, “Weirs – Planning, Building, & Measuring Flows“.  In that post explaining the essentials of installing a weir box, I had said to excavate the pad 4” deep and fill with base rock.  It should have said, excavate 8″.  I’m sure you already figured out why:  the weir bottom is about 4″ thick, so the weir floor would have been above the bottom of the ditch.  By excavating 8″, and then filling with 4″ and compacting a level pad of 3/4″-minus road base, when the weir is placed the floor of the weir will be level with the bottom of the ditch.  That way, the weir is not too high, where flow will undercut
Weir_Set_No_Backfill_edit_smallthe base, and it is not too low, requiring extra boards to get a still pool upstream of the weir.  The weir box in this photo is set – all it needs is for the water to be shut off, sides backfilled, and boards put in for easy measurement.

The important factor in figuring out where the weir gets placed along the ditch, is that the ditch needs to be straight upstream of the weir box.  You can see in the photo above that the weir is located in a straight section of the ditch.  When the box is placed in alignment with the straight ditch, the approaching water does not have to make a turn.  Water going around a bend rolls toward the outside of the bend, and rolling or turbulent water might give a false reading of depth over the weir boards.

How long does the straight section of ditch have to be?  The wider the weir, the longer the length of the ditch has to be straight.  For a 1.0 foot-wide (1.0′) weir, which would pass a maximum of 1.0 cubic feet per second (cfs) if it worked as a suppressed weir, the minimum distance should be about 10′.  For a wide weir box of 6.0′, the upstream distance should be 70′ or 80′.

How high do the boards have to be to provide an essentially still pool upstream of the weir?  Remember the rule that the static head going over a weir, or the height of water that climbs up a 1/2″ engineering ruler held face-on to the flow, should be a maximum of 0.45′.  A suppressed weir, with the flow width going from wall to wall as it goes over the weir, has to be 3 times that 0.45′, or 1.35′.  2  2″ x 8″ boards stacked up will get this height.  If the weir is contracted, or cut into the board, then the board height only has to be twice the static head, or 0.90′.  A 2″ x 12″ would take care of this.  However, to be sure, never use less than 2 2″ x 8″ boards.

One more thing – the weir has to keep from collecting dirt or sand behind the boards.  That means the boards may have to be lifted up every so often so the sediment can flush out.  Weeds have to be kept down all around the weir so they don’t affect the flow of water.  In the same way, sticks and grass have to be kept off the tops of the boards for the weir to work correctly.WMM_Cover_small

Where can you find all this information yourself?  As always, check the bible for measuring flows, the USBR Water Measurement Manual.

That’s enough for now, more to come soon!  Have a great week and I hope it rains today where you are.

Coming Soon, Free Ebooks on Measurement Device Installation and Flow Measurement

The All Water Rights Blog has most or all of the information needed for a farmer or rancher to install a simple measuring device that is compliant with the recent regulations of the State Water Resources Control Board.  I’ll have a couple of free ebooks by June, on how to Red_Books_Edited_3install pre-cast weirs and orifices, as well as how to use them correctly, and report flows from small diversions to the Water Board.  Actually, the ebooks will apply to larger diversions, too, except for the necessary pressure transducer needed to report hourly (and some day, 15-minute) flows to the Board.GE_PT878

There are certainly more complicated devices that require help, such as cast-concrete
Parshall and other flumes, mag-meters, acoustic Dopplers, or full-on gaging stations on rated sections of streams or ditches.

However, most diverters can (and many do) comply with the law with relatively simple devices.  That’s it for now, I just wanted to get the word out on this.

Oh, and there will be an ebook some time around August, which has a working title of “Practical And Applied Water Rights In California – The Non-Attorney Book For Diverting Your Water”.  That book will be more complete and will cost something, yet to be determined.  Let me know what YOU want to see included in a book like this.

Have a great day, pray for more rain and snow!

How Good Is Good Enough? Water Board Required Accuracy of Your Measurement Device

How accurate does your measurement device have to be?  The Water Board gives those numbers in the Fact Sheet at http://www.swrcb.ca.gov/press_room/press_releases/2016/pr12016_measurement.pdf; see the bottom of this post for the excerpt on accuracy.

When talking about new weirs, orifices, flumes, mag-meters, and acoustic Doppler devices, plus or minus (+/-) 5% accuracy is expected of new, properly installed, regularly maintained, correctly operated devices.  What does that mean?  If your diversion rate is measured at 1.00 cubic feet per second (cfs), then you would expect the true value to be between 0.95 and 1.05 cfs.  If your diversion rate is 5.00 cfs, then the true value would be between 4.75 and 5.25 cfs.  The total accuracy is 10%, we just don’t know if measured values are really up to 5% less, or 5% more than calculated.

New devices might actually have better accuracy than +/- 5%.  Engineers never count on that because a bunch of factors, known and unknown, can stealthily make the accuracy worse.  Accuracy also depends on the measurer – some are better than others, some are better trained and experienced, and most take the job seriously but some do not.

Of course, accuracy gets worse as measurement devices age.  Why does this happen?  There are a number of reasons:

  • Settling, so the device is not level front to back, or side to side, or both
  • Cracking, so water leaks out, or the cracked wall is not straight (planar)
  • Wear, spalling, chipping, and other roughening in the device floor and walls
  • The ditch fills in downstream, causing submergence
  • Old boards that warp and leak
  • Installed staff gages wear, making them harder to read correctly
  • Etc.

The USBR Water Measurement Manual has 14 chapters, and all of Chapter 3 discusses accuracy in great detail.  That’s the “Bible” of water measurement so we would expect it to be, well, accurate in its discussion of accuracy.

http://www.usbr.gov/tsc/techreferences/mands/wmm/index.htm

It is not clear to me yet whether the Board’s accuracy numbers are +/- values, meaning the allowed accuracy is +/- 15% for diversions less than 100 acre-feet (AF) per year, and +/- 10% for diversions greater than 10 AF per year.  If so, that seems reasonable because that allows for some aging of measurement devices.  Otherwise, the Board would expect measurement devices to always be in new condition for diversions greater than 100 AF per year or storage greater than 200 AF per year.  That would be pretty expensive!

That brings up the subject of money – accuracy requirements hit your pocketbook.  First you have to either install or pay for a measurement device to be installed.  Hopefully the device will last 20 to 30 years, but high flows, getting walked on by cattle, freezing and thawing, settling faster than expected, and other events can wear them out faster.  The replacement cycle might be 10 years for some diversions, or even 5 if wear and tear is bad.

Board_FactSheet_MeasurementAccuracy

This post may be more than most people want to read on the subject of accuracy.  Still, it’s a lot shorter than Chapter 3 of the Water Measurement Manual!

That’s all for now, have a great rest of the week.

Coming to a Diversion Near You – Water Board’s 2017 Measuring, Reporting Requirements

Continuing our discussion from a previous post, https://allwaterrights.com/2016/01/27/diverters-must-report-weekly-daily-or-hourly-starting-2017/, surface water diverters must have some kind of measurement system, and must report diversions more frequently.  The Water Board posted a fact sheet online that summarizes the emergency regulations:  SENATE BILL 88 AND EMERGENCY REGULATION FORMEASURING AND REPORTING ON THE DIVERSION OF WATER

Many diverters, particularly those who report less than 100 acre-feet (AF) per year, can find enough information in this blog to successfully install their own measurement devices.  100 AF per year is equivalent to a year-round, 24-7 diversion of 0.140 cubic feet per second (cfs).  If the diverter only uses water during the irrigation season, the equivalent rate is higher.  For example, a diversion for 90 days is only 1/4 of a year, so the rate is proportionately 4 times greater:  0.560 cfs.

What are some of the other regulations?  Here are a few from the January 8 version, which still has the edits shown.  The first is that diverters must “immediately” report changes in name, address, or ownership.  Sometimes, buyers of property don’t even know they have a permit or license!  Not immediately reporting something a buyer is not even aware of, puts the new owner in legal trouble:20160108_prop_regs_S_915-916

There are changes in the regs which we have already discussed, in measurement devices, reporting frequency, and who is legally qualified to install measurement devices:

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More on the regulations later, including additional information about how to comply with the law, stay out of trouble, and protect your right to divert water