## Is John Stealing Water?? Orifices – Right Size and How to Measure

Is John Stealing Water??  John Casey has a cattle ranch near Adin, where he grows pasture and hay to raise about 70 Angus steers.  His place is 240 acres with lower irrigated land and forest on the higher part.  He has an adjudicated water right of 2.00 cubic feet per second (cfs) from Preacher Creek, to irrigate 80 acres.

John’s downstream neighbors claim he steals water.  He says he can show that he takes only 2 cfs, or less when the flow drops down in the summer.  Can he prove it?

As we can see, he has a square headgate at the head of his ditch.  It is 2.0′ wide, and can open up to 1.5′ high.  Right now, John says he is diverting 1.05 cfs.  His evidence is that his gate is open 0.15′, the water is 0.57′ deep on the upstream side, and the water is 0.20′ deep on the downstream side.  Is that enough to check what he says?

The box in which the gate sits has smooth walls, and the gate closes flush with the bottom when John is not diverting.  The water continues in a straight path from upstream to downstream.  That means the weir has “suppressed” sides.

This is in contrast with, for example, a hole cut in the middle of a 2″ x 12″ weir board.  The water on the sides has to make the turn to go straight through, so the hole in the board is an example of a “contracted” orifice.

Let’s look at the tables for orifices in the back of the Water Measurement Manual.  Table A9-3 is for submerged, suppressed weirs.

We can’t see the downstream side of the weir, but the water is above the bottom of the edge of the gate, so it is submerged rather than free-flowing.

This table has flows calculated for a minimum area of 2.0 square feet (sq. ft.).  However, the area of the opening at John’s headgate is 2.0′ wide x 0.15′ high, or 0.30 sq. ft.  Fortunately, the equation, Q=0.70A(2g Δh)^0.5, is listed right at the top of the table.  We can calculate the flow using that.  Q is the flow in cfs, A is the area of the orifice hole, g = the acceleration due to gravity, or 32.2 ft/second^2 (feet per second squared), and Δh is the difference between the upstream and downstream water depth.

So the flow Q = 0.70 x (2.0′ x 0.30′) x (2 x 32.2 x 0.37′)^0.5 = 1.03 cfs.  So far so good – John is taking 52%, or just over half of his right when 100 percent of flows are available.  But, how much flow is actually available right now?

Let’s use the “sum of the boxes” method.  Instead of measuring the amount of water in Preacher Creek at the top, before any diversions, and then estimating how much flow is being lost to evaporation, transpiration, and infiltration, and then estimating how much flow is subsurface above John Casey’s ranch and “pops up” out of the ground below, we’ll look at what each diversion amount is, plus the amount still in the creek after the last diversion.  This is very useful because none of the instream losses have to be estimated – we just add the diversions and flow still in the creek, and that amount IS the available supply.  Some Superior Court judges in past decades were pretty smart and actually ordered that available flows be calculated this way.

The paragraph above, from the Susan River Decree, defines available water supply as what is being diverted, plus the flow passing the last diversion.

There are 4 diversions on Preacher Creek, and here are the amounts being diverted:

• Diversion 1 (John Casey) 1.03 cfs  of a 1.60 cfs water right, 52% of his total right
• Diversion 2 (Amy Hoss) 1.67 cfs  of a 3.80 cfs water right, 44% of her total right
• Diversion 3 (Mark and Cindy Sample) 0.55 cfs  of a 0.88 cfs water right, 62% of their total right
• Diversion 4 (Quint and Marcie Minks) 1.32 cfs  of a 2.50 cfs water right, 53% of his total right
• Flow still in the creek past the Minks Diverison – Quint estimates about 0.7 cfs

The total diversion-plus-bypass flow is about 5.3 cfs.  The total rights on the creek are 9.48 cfs.  Therefore, the total available flow = 5.3 / 9.48 = 56%.

So, John is right, he is not stealing water!  He is taking 52% of his water right, when he could be taking 56% according to the “sum of the boxes” method.  Not only that, but Amy could take more, the Samples should reduce their diversion, and the Minks’s could take a tad more.  Well, that’s theoretical – Quint and Marcie Minks probably cannot seal up their dam completely, so there may be a little bit less flow actually available for diversion.

## From weir to orifice in only an hour

Orifice devices are needed for flat ditches, where the fall may be as little as 0.20′ (2.4″) from upstream to downstream.  An orifice is simply a hole through which water flows, so it can be accurately measured.  The photo below shows a submerged weir, flowing from right to left.  The water in the ditch downstream (left) is above the hole in the boards. You already noticed the amazing thing about this orifice, didn’t you?  I could tell you are savvy that way.  Yes, this is the same Briggs Manufacturing weir box as the ones in the previous post!  It has the same 2″ lumber in the upstream board slot.  Now the flow goes through a precisely cut hole in the boards, with a known area, instead of over the top of the boards.

Installation is just like with the weir boxes installed in the previous post, too.  For convenience, staff gages may be attached to one side of the box so it is quick to read the water depths.  So the precast concrete box is versatile, it can be used as both a weir and an orifice.  Actually, some ditches need both a weir and an orifice.  This is especially true in a ditch where a gate or boards may be put in the ditch below the weir box, to flood hay or pasture just below the measurement device.  All it takes is a change of a couple of boards.

The big difference in measuring the flow is that, instead of “sticking” the weir boards, now the depth of the water must be measured upstream and downstream to use a weir equation or table.  The “difference in head”, or water surface elevation, gives us a value needed to read the table or use an equation to figure out the flow.  What tables or equations?  These are out of the water measurement bible, the Water Measurement Manual.  We will discuss these very soon in following posts.

This was a quick post to show how you can get 2 uses out of one device, to make your life simpler.  That’s all for now, hope you had a Merry Christmas!

## Weirs – Planning, Building, And Measuring Flows

Tomorrow is Christmas 2015!  Merry Christmas all.

Weirs are the least expensive permanent measurement device you can install.  Materials will cost the diverter in the range of \$300 to \$2,000; hiring the backhoe to set it in place probably costs more than the materials, unless the diverter already has a backhoe or crane.

The weir below was precast by Briggs Manufacturing in Willows.  The weir is a cast concrete, 3-sided box with board slots for 2″ lumber.  It’s pretty simple, and relatively easy to install.  This particular weirneeded metal wing-walls to keep the dirt on the sides from washing out.  Note that there are two board slots on each side, one for the boards to slide in, and the other to help make sure a nappe or air gap is created as water flows over the boards.

Step one is determining if there is enough fall in head from upstream to downstream.  A weir needs 0.7 feet (0.7′), or 8.4 inches (8.4″) of fall to be sure it will work correctly.  The 0.7′ figure is because the pool of water needs to be a maximum of 0.45′ above the top of the weir boards on the  upstream side.  Then, the water in the ditch downstream of the weir needs to be at least 0.25′ below the top of the boards so the water flows freely, separating from the boards and having an air gap on the downstream side.  0.45′ + 0.25′ = 0.70′.

The photo above shows a ruler in tenths of a foot, held vertically on top of the weir boards.  This is called “sticking the weir”.  When the ruler is turned face-on to the flow, the water will climb up to the same level as the flat pool upstream of the boards.  It’s physics – standing water has an energy level equal to the height of the water surface.  Moving water has both potential and kinetic energy, so the energy level or line is above the surface of the

water.  Moving water stalls behind the face of the ruler, giving the height of the water if it were standing still.  That is the water depth that has to be measured for weirs.  The photo is showing a water level of 0.31′ – it wobbles up and down just a little – so we know this weir is flowing at about 0.6 cfs per foot of width.

If the ditch is very flat and shows no ripples when flowing, it’s probably too flat, and an orifice or a flume will be needed instead of a weir.  Future posts will discuss those measurement devices, and others too.

Step 2 is figuring out how big a box is needed.  Fortunately, there is an easy rule.  1.0′ feet of width is needed for every cubic foot per second (cfs) that will be diverted.  For example, if the diversion will be a maximum of 3 cfs, then the diverter will need a 3′ wide weir.  If in doubt, get the next larger size since the cost is not much more.  The reason for this rule is that a weir can be accurate to plus or minus 5%, well within the accuracy needed for diversions in the field.  If the pool upstream of the weir boards is more than 0.45′ over the top of the boards (or less than about 0.1′ over the top of the boards), the accuracy of the weir is worse than the standard.

Measurement devices need to be planned and operated correctly to assure the diverter (and ditch-tender, and neighbors, and the State Water Resources Control Board, andpossibly 10 other state and federal agencies, and possibly even the Superior Court in the very worst case) that the flow measurement is correct.  It’s like a truck speedometer – they can get less accurate over time.  It’s no problem if they read faster than the driver is actually driving, but if they read slower, the driver is in danger of unknowingly speeding and getting a ticket.  Ouch.

The actual installation process is fairly simple to describe.  Get 1 to 4 yards of 3/4″ minus road base rock delivered on site, trucked from the gravel plant.  To save a lot of hassle, skip the forming up and pouring a concrete weir, and just call Briggs Manufacturing and order a weir to be delivered on site.  Dig a shallow, level (flat), square hole in the bottom of the ditch, about 8″ deep, and 1′ longer and wider than the bottom of the weir.  Shovel base rock into the hole about 2″ deep, and compact it.  Rent a gas-powered thumper, or use the bucket of the backhoe.  Pour another 2″ and compact it.  Use a level and make sure the top of the base rock is level side to side, and along the ditch.  Since it packed down during compacting, add the last 1″ and compact it, so the top of the road base is about 4″ below the bottom of the ditch upstream and downstream.

The installer needs to make sure to have a piece of 1″ steel bar that is about 1′ longer than the the width of the weir box.  There is one hole through the top of each side of the weir – stick the rod through that and hook onto it with a chain to lift the weir.  Set it in place, and make sure it is sitting level.  The installer might have to gently press down on one side with the backhoe to get it completely level.  Now the floor of the weir will be at the level of the bottom of the ditch.  Remove the steel bar, and fill the weir box inside about 2′ deep with some dirt.

Next, install the wing-walls, if needed.  These will keep the material on the outsides of the weir from washing out in a steeper ditch.  Then backfill with the remaining road base on the sides, compacting it for each 6″ of depth.  If the native soil holds water well, it could be used instead of base rock to backfill, saving a little bit of money.  Remember the dirt that was placed 2′ deep inside the weir?  This will keep the weir weighted down so it does not move during backfilling.  Also, it will keep the sides from being slightly bent in by the pressure of compacting the backfill.  The reinforced concrete weir boxes are strong but the walls can be bent in with enough force.

That’s it!  The weir box is installed and ready to go.  New weir boards, usually 2″ x 6″ or 2″ x 8″, should be cut about 1″ shorter than the width inside the board slots.  For example, a 3′-wide weir will have board slots about 2″ deep.  The full width from inside of board slot, to inside of the opposite board slot, is 3′-4″.  The boards should be cut about 3′-3″ long.  That way, when they swell a little bit, they won’t get impossibly stuck.

Happy measuring!  Good night to all, Merry Christmas, and blessings in the New Year.

## Life Of Reilly: If You Can’t Measure It, You Can’t Manage It!

A friend of mine, Chris Reilly, summarizes everything you need to know about measuring flows into your surface water diversion:  “If you can’t measure it, you can’t manage it!”  Except for riparian rights and some very small water rights, diverted flows have to be measured.  Why?

Legally, to ensure your neighbors, the Board, and/or a Superior Court Judge that you are diverting no more than your water right.  Practically, how do you know if you are getting as much water as you should?  As surface flows decrease through the summer, every bit less means some pasture, hay, orchards, row crops, or something else does not get irrigated.

If you have never measured flow into a ditch before, well, here goes, I am going to leak the secrets right here, I’m going to violate the Unspeakable Code Of The Water Measuring Brotherhood, the ve
ry deepest, most powerful wisdom of how to measure your flow will appear on this very page.  After this, who knows if you will ever hear from me again, once this classified information is made public?  Well, not really, but few people have heard of the Bible Of Water Measurement, the
USBR Water Measurement Manual (WMM)

Let’s look at 3 common measurement devices detailed in the manual:  weirs, orifices, and flumes.  Properly installed and maintained, these devices can measure flow within plus or minus 5% of the actual amount.  The photos below are from the WMM, which has lots of diagrams that make it easy to see the details of how each device works.  First, the weir:

You have seen these before, they’re just a level plate or board of a specific width, with a relatively still pool behind them.  That’s it!  By measuring the height of the pool above the edge of the plate or board, you can use tables or equations from the WMM to determine what the flow is.

Above is shown an orifice.  Not much to see, is there?  In this case, it is just a hole, lower than the upstream flow.  That is physically all an orifice is.  Knowing the size of the hole, and how high the water is over the center of the hole, and how high the water is down the ditch, a table or equation can be used to figure out the flow.  The gentleman above is using a square gate with a certain width.  The area changes with how high the bottom of the gate is, not hard to figure out.

The photo above shows a Parshall Flume.  These are great for measuring high flows without needing a lot of “head” or the drop in the water from upstream to downstream.  By knowing the depth at a certain point, a table or equation can give the flow amount.

We’ll go into how to use tables for specific measurement devices in later posts.  It’s enough for now to know that if you have a decent measurement device, then you CAN manage your flow, as well as proving that you are taking no more than your legal water right.

## Quick Change of Subjects: What’s a Water Right Permit Cost?

What does it cost to get a surface water right?  If your land is not riparian to the stream where the water is, or maybe one parcel is but your other 5 parcels are not, then you’ll need to file for a (Post-1914) appropriative right with the State Water Resources Control Board.

Let’s say you want to irrigate 50 acres of new almond orchard in the Sacramento Valley.  How much water do you need for micros-sprinkler irrigation?  Let’s use the value for a 5-year-old orchard, about 3.33 acre-feet (AF) per year for irrigation and frost protection.  That number comes from the U.C. Davis Report Sample Costs To Establish An Orchard And Produce Almonds Sacramento Valley – 2012, at http://aic.ucdavis.edu/almonds/cost%20studies/AlmondSprinkleSV2012.pdf ,

The total annual volume of water for 50 acres is 3.33 * 50 = about 167 AF/year.  That equates to a constant flow of 0.03 cfs.  But, you probably irrigate one day per week, so 7 times the average rate = 0.21 cfs. So, in your permit application, you would need to apply for 167 AF/year, diverted at a maximum rate of 0.21 cfs.

To get the rate for filing for a permit with the Board, we need to check the fee schedule:   http://www.waterboards.ca.gov/waterrights/water_issues/programs/fees/docs/fy15_16_fnl_fee_schd_sum.pdf

So your application fee would be \$1,000, plus \$15 per AF over the first 10 AF.  Your cost would be \$1,000 + (167 AF – 10 AF) * \$15/AF, for a total of \$3,350.  There is also an annual cost:

Your annual fee would be \$150 + \$0.063 per AF over the first 10 AF.  Your annual cost would be \$150 + (167 AF – 10 AF) * \$0.063/AF, for a total of \$160/year.

Of course, these costs are if it’s a “slam dunk” and there are no complications.  There would likely be a 1602 permit required by the California Department of Fish and Wildlife, and there could be other permits.  If anyone contests the application, then you would have more fees (see the schedule), perhaps attorney fees, and perhaps a negotiation to use water from someone else’s diversion.

## California Water Right Holders Now Required To Have Measuring Devices

Water laws are changing at lightning speed because California is in a historic drought. Groundwater law was passed requiring local agencies to be formed to manage groundwater. In 2012, I thought that would take 20 years to happen. The drought accelerated it to 2 years.

Surface water laws were passed in 2009, greatly increasing penalties for not reporting diversions, for misreporting, for overdiverting – in short, for evading, lying, and stealing. Suddenly tens of thousands of diverters who had been ignoring the State Water Resources Control Board started to worry. How do I report, am I in hot water if the Board sends me a letter, how do I figure out what my water right is?

The California Water Code Section 5100-5107 has the new, more restrictive part of the Water Code.

For example CWC 5103 (e) (B) says:

” (i) On and after July 1, 2016, the measurement of a diversion of 10 acre-feet or more per year shall comply with regulations adopted by the board pursuant to Article 3 (commencing with Section 1840) of Chapter 12 of Part 2. “

That doesn’t sound too bad. But what does CWC 1840 say?

” 1840 (a) (1) Except as provided in subdivision (b), a person who, on or after January 1, 2016, diverts 10 acre-feet of water per year or more under a permit or license shall install and maintain a device or employ a method capable of measuring the rate of direct diversion, rate of collection to storage, and rate of withdrawal or release from storage. The measurements shall be made using the best available technologies and best professional practices, as defined in Section 5100, using a device or methods satisfactory to the board, as follows:
(A) A device shall be capable of continuous monitoring of the rate and quantity of water diverted and shall be properly maintained. The permittee or licensee shall provide the board with evidence that the device has been installed with the first report submitted after installation of the device. The permittee or licensee shall provide the board with evidence demonstrating that the device is functioning properly as part of the reports submitted at five-year intervals after the report documenting installation of the device, or upon request of the board.
(B) In developing regulations pursuant to Section 1841, the board shall consider devices and methods that provide accurate measurement of the total amount diverted and the rate of diversion. The board shall consider devices and methods that provide accurate measurements within an acceptable range of error, including the following:
(i) Electricity records dedicated to a pump and recent pump test.
(ii) Staff gage calibrated with an acceptable streamflow rating curve.
(iii) Staff gage calibrated for a flume or weir.
(iv) Staff gage calibrated with an acceptable storage capacity curve.
(v) Pressure transducer and acceptable storage capacity curve.
(2) The permittee or licensee shall maintain a record of all diversion monitoring that includes the date, time, and diversion rate at time intervals of one hour or less, and the total amount of water diverted. These records shall be included with reports submitted under the permit or license, as required under subdivision (c), or upon request of the board.
(b) (1) The board may modify the requirements of subdivision (a) upon finding either of the following:
(A) That strict compliance is infeasible, is unreasonably expensive, would unreasonably affect public trust uses, or would result in the waste or unreasonable use of water.
(B) That the need for monitoring and reporting is adequately addressed by other conditions of the permit or license.
(2) The board may increase the 10-acre-foot reporting threshold of subdivision (a) in a watershed or subwatershed, after considering the diversion reporting threshold in relation to quantity of water within the watershed or subwatershed. The board may increase the 10-acre-foot reporting threshold to 25 acre-feet or above if it finds that the benefits of the additional information within the watershed or subwatershed are substantially outweighed by the cost of installing measuring devices or employing methods for measurement for diversions at the 10-acre-foot threshold.
(c) At least annually, a person who diverts water under a registration, permit, or license shall report to the board the following information:
(1) The quantity of water diverted by month.
(2) The maximum rate of diversion by months in the preceding calendar year.
(3) The information required by subdivision (a), if applicable.
(4) The amount of water used, if any, for cannabis cultivation.
(d) Compliance with the applicable requirements of this section is a condition of every registration, permit, or license.
(Amended by Stats. 2016, Ch. 32, Sec. 98. Effective June 27, 2016.) “

Now THAT has a punch. There are exceptions in following paragraphs, but the Board now wants “continuous monitoring”, meaning one of the older, mechanical Stevens Recorders and the like, or newer, electronic pressure transducers. Now we are talking \$500 and up just for recording data, in addition to a measurement weir, flume, or orifice.

And the diverter has to provide “evidence”. How is that done? Is a photo good enough? A video? A drawing? A statement by the local ditch tender, the Resource Conservation District, a technician, or an engineer?

Of course, the Board has higher priorities with larger diversions, and streams with anadromous (chinook and steelhead) fisheries. Still, it is an open question about when the Board will get to your or my diversion.

Complaints from neighbors with a grudge tend to elevate problems that the Board considers. But, water is nothing to argue over, is it? Or have grudges?

More on this later. Good night to all.