## Is John Stealing Water?? Orifices And Sum Of The Boxes

This is updated from a previous post, which was an example for a stream with adjudicated water rights.  However, it also works for any stream where there are water rights with legally defined diversion quantities, if all the diverters have headgates in good condition and/or measurement devices such as weirs, flumes, and pipe meters.

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 ranch is 240 acres with lower irrigated land and forest on the higher part.  He has an a licensed water right of 2.00 cubic feet per second (cfs) from Preacher Creek, to irrigate 80 acres, from April 1 to November 1.

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.

Water Board Permits and Licenses are usually not interrelated – they specify water rights without considering the other water rights on the stream.  This is different from adjudicated streams, whether done by the Water Board or the Department of Water Resources.  Some Superior Court judges in past decades were pretty smart and actually ordered that available flows be calculated by the sum of the boxes:

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.

## Update – Who To Call At The Board?

A question I often hear is, “Hey, I got this letter/a call from the State Water Resources Control Board.  What am I supposed to do about measuring my flow?”  The main number for the Water Board is (916) 341-5300 – and these folks have much more work to do than time to do it.  Several calls may be required to reach a knowledgeable person who isn’t already talking to two telephone calls, or making three investigations in the field.  So, start with the main contact, Paul Wells, who is very knowledgeable and can get you the answers or the person you need to talk to.

By the way, Thank You to Kathy Mrowka, who has been reasonable in working with diverters who are trying to comply.  What she says often is true:  talk with her and/or others at the Water Board and you’ll likely get consideration, some more time to comply, and reduced (maybe greatly reduced) fines.

Since many calls I get are about enforcement letters, calls, or visits from the Board, it’s probably most useful to have the phone numbers and emails from Enforcement Program Staff.  Here they are, from the Water Rights Enforcement Program Web Page:

## Enforcement Program Staff

 Katherine Mrowka, Manager (916) 341-5363 Paul Wells, Senior WRCE Specialist (916) 323-5195

Central Coast/So. Cal Unit San Joaquin Valley Unit
Laura Lavallee, Supervisor
(916) 341-5422

Ramon Ruiz
(916) 341-5411

Kyle Wooldridge
(916) 323-9405

Janelle Heinzler
(916) 323-9406

Dave LaBrie
(916) 341-5343

Brian Coats, Supervisor
(916) 341-5389

Chuck Arnold
(916) 341-5634

Matt Quint
(916) 341-5380

Damon Hess
(916) 341-5345

Jeff Yeazell
(916) 341-5322

Sacramento Valley Unit North Coast Unit
Victor Vasquez, Supervisor
(916) 323-9407

Michael Contreras
(916) 341-5307

Kathy Bare
(916) 327-3113

Oxcar Macias
(916) 341-5637

Natalie Stork
(916) 322-8425

Tomas Eggers
916-327-8039

Taro Murano, Supervisor
(916) 341-5399

Michael Vella
(916) 327-3114

Skyler Anderson
(916) 341-5355

Kevin Porzio
(916) 323-9391

Bill Rigby
(916) 341-5376

Vacant

## How Do I …. ? (Determine My Water Rights, Measure Flows, Report Flows , Etc.)

See the new “How Do I … ?” link on the left.  There are so many posts on this blog, it is getting harder to find stuff.  Click on the link, or right-click then “Open link in new tab”, and the big questions are linked to the appropriate blog posts.

Another way to search is, as always, Google.  For example, googling “allwaterrights measure weir” brings up the following results:

## Can You Save Some Bucks? Flow Device Economics by CDWR

What is the cheapest flow measurement device to install, that is durable, accurate, and easy to maintain?  The California Department of Water Resources (CDWR) Red Bluff office wrote a memo in October of 2010, detailing findings on flow measurement devices over decades of watermaster service.  Part of the memo is summarized here – not direct quotes:

##### Economics of Flow Measurement Devices

CDWR watermasters helped water right holders to install and operate a variety of structures over eight decades.  Physical factors such as flow range, ditch width and slope, soil type, whether or not a site is protected from livestock, and access to the site, play a large role in picking the right device.  Cost is also important,  including design, installation, replacement, operation, maintenance and repair.

The following chart shows the relative costs that the watermaster service and water right holders have experienced for various devices. The chart shows that pre-built weirs are the least expensive to install and repair. Flumes are the least expensive to operate, but are the most expensive to design and construct or install.

Some considerations for the proper use of weirs are:

1.  Always seal leaky flashboards with sediment, horse manure if available, and if necessary, sheet plastic.  Use newer flashboards, replaced every year or two, and trim boards on site to ensure a level top board, and reduce gaps prior to use.
2.  1.5 inch (2″ nominal lumber e.g. 2″ x 8″) flashboards are not measurably less accurate than a thin steel plate metal with sharp edges, provided that the head on the weir is great enough to cause separation of the water from the upstream edge of the flashboard.  The air bubble on top of the board is easy to see when the weir is working right.  The minimum required head is around 0.25 feet.  As an example, CDWR watermasters compared the use of flashboards to
sharp-crested weirs on November 20, 2008, as they have done several times in the past.  Differences were recorded and weirs with flashboards had flows that were both slightly less and slightly more than the flows calculated for sharp-crested weirs.  Any difference is well below the margin of error when taking into account all possible errors.  In summary, 1.5-inch flashboards provide results indistinguishable from sharp-crested weirs for the use of measuring diverted flows.
3.  CDWR designed the Briggs-manufactured Twin-Track Weirs© with two flashboard slots.  The upstream flashboard slot holds the nominal 2-inch wide weir flashboards.  The downstream slot provides the air gap for the nappe, as specified in the USBR Water Measurement Manual, 3rd Edition, 2001, in Figure 7-8 on Page 7-13.
4.  CDWR measures weir heads with weir sticks, as specified in the USBR Water
Measurement Manual, 3
rd Edition, 2001, on Page 13-4.  CDWR has checked the use of weir sticks numerous times and found the difference between the head measured with a weir stick and that at a staff gage nearly always to be 0.00 feet (the same to the hundredth of a foot).
5.  Even when diverters are careful, the amount delivered may occasionally be somewhat more than the water right as streamflows vary due to diurnal fluctuation, changes in upstream diversions, and from increased flows due to storm events.  However, more than half the time when flows are not at the legal amount, they are less than the water right amount for the following reasons:
• Floating debris sometimes accumulates on the upstream side of a diversion headgate, reducing flow.
• Water right holders who grow hay shut off their diversions to cut, dry, bale and haul hay for several days, reducing their total volume of diversion.
• Irrigation season damage to ditches requires diversions to be reduced or stopped during repairs.
• Weed growth or sediment in the ditch reduces the hydraulic capacity of ditches.

## Smart Ranchers & Farmers Save Money for Them AND You

A local farmer, rancher, and apiarist, whose name you likely know, referred me to a pretty smart ranching friend of his who has been researching more cost effective flow measurement and data collection schemes.  This retired aircraft engineer has found data collection devices with installed costs in the \$500 – \$600 range, instead of \$1,200 up to \$20,000.  I’ll publish their names if they agree later; they should have a chance to read this before they put their names on it.

They aim to save themselves and all of you some of your hard-earned money.  I really want to see what data collection setups are available, hopefully this week there will be an all-in-one system that meets State requirements and is not such a budget-buster.  There are also be some pre-fabricated flow measurement devices that can be easily dropped in a flat ditch where a weir (the least expensive device) won’t work, saving money compared to a formed-up flume.

From my years at DWR, my coworkers and I dealt with the trade-off between high accuracy and durability, at a high cost, and reasonable accuracy and lower durability for less money.  This was always the tension, whether acquiring surveying equipment, portable flow measurement devices, or flow gaging components like data collectors, bubbler pressure sensors, or GOES satellite radios.

You have probably seen this triangle before – it is useful for planning prrojects.  For the purposes of evaluating data collectors at diversions, Time is the owner’s, contractor’s, or engineer’s level of effort to make a diversion comply with the law.  Scope is meeting the Water Board requirements – the length of that side cannot change.  Everyone, including me, wants to reduce the Cost side of the triangle.  Reducing Time means getting the labor, equipment rental, engineer’s report, and certification done cheaper – it’s the other way to reduce cost.

What is the effect of reducing cost?  The size of the triangle equals quality, and that goes down.  How much loss of quality is acceptable?  In the case of data collectors, quality equates with the durability – maybe the device will only last 2 years instead of 4, or maybe it is twice as likely to quit working in the middle of an irrigation season.  If quality goes down too much, then the data collection scheme will not meet Water Board requirements.

On the other hand, computer technology and sensors have improved over the years.  Computing costs a tiny fraction of what it once did.  Sensors have come down in cost a little, while their quality has improved somewhat.  Maybe we can get just-fine data collection at half the cost – we’ll see!

## How Do I Comply With Water Board Regulations? Part 3

In Part 2, How Do I Comply With Water Board Regulations? Part 2, we considered the question:  Who has to have a certified, accurate device by January 1, 2017? How often is it monitored?  The answer is, those who divert 1,000 acre-feet (AF) per year or more, and it has to be monitored hourly.  What size diversion is this, really?  An irrigation diversion of 1,000 AF over 6 months, with flows starting at 100% of the water right, declining to 50% of the right by the end of the season (month 6) would calculate out to a water right of 3.68 cubic feet per second (cfs), or about 3.7 to 4.0 cfs (cfs).  Depending on where you are, that irrigates somewhere between 80 and 400 acres of hay or pasture.

In this post, I’ll answer 2 questions:

1. What if your water right is smaller than 3.7 cfs, diverting 100 AF to 1,000 AF per year?
2. A BIG question right now: What is “alternative compliance”, and how might it be done to meet the Water Board’s regulations?

To answer the first question, the next category down is 100 AF to 1,000 AF per year.  Using the example of a 6-month irrigation season, with a diversion that starts at 100% of the water right and gradually declines to 50%, the water right we’re talking about is about 0.37 to 3.7 cfs.  This category does not have to comply as quickly – the deadline is July 1, 2017, or nearly a year from now.  The measurement frequency is daily, which is possible to be done by a diligent person, if not not recorded automatically.  For a sense of how much water this is, depending on where you are, what the soils are like, and how efficient the diversion is, the acreage of hay or pasture irrigated ranges from about 8 to 370 acres.

What kind of measurement devices would meet the regulations?  The same types that we discussed in Part 2, but ranging down to smaller sizes:

• weirs as little as 0.5′ (0.5 feet, or 6″) wide, or wider with boards cut to make contracted weirs
• free-flowing orifices with holes down to 0.16 x 0.16′ (2″ x 2″) square and a piece of steel plate to adjust it smaller
• submerged orifices down to 0.25′ x 0.25′ (3″ x 3″) with an adjustment plate.
• small flumes and meters

The photos above show smaller-sized devices than the 4′ weirs shown in earlier posts.

The second, and these days much BIGGER question, what about alternative compliance?  The Water Board requires submission of alternative compliance plans on a form that is not yet available.  If it were my diversion, I would not worry about that; I would put together my plan and send it in.  The old rule applies that if you are not sure who to send it to, send it to several managers and maybe a Deputy Director.  Emailing documents is cheaper; most computers will let you print to PDFs that can be emailed.  Your submittal probably will not be accepted this way but the point is, the Water Board cannot say that you have not attempted to comply.  Not complying at all can be very expensive; “Do something wrong, instead of nothing at all.”

This screenshot is from an OLD, no longer valid Statement Of Use form, but it
gives some ideas of what options for alternative compliance the Water Board has in mind.

What has to be in your alternative compliance plan?  From the Water Board’s ADOPTED TEXT OF EMERGENCY REGULATION, the text gives 12 parts that must be in the plan (below).  The plan may be rejected – having a plan (instead of a standard, certified measurement device) is no guarantee that the Board will accept it.  In summary, the plan must detail contacts for all people on a ditch, Assessor Parcel Numbers, the water right(s), priority(ies), use(s), diversion(s), ditch(es) and/or pipe(s), measurement frequency and methods, dates for milestones and completion, permits required, financing plan, and map(s) showing the plan area including all physical features and place of use…and all of this must be signed by all water right holders on the ditch (the emphasized text in the bullet points is mine):

“…………  §935 Alternative Compliance for a Measuring Device or Measurement Method Requirement.

(a) Alternative Compliance – Generally. In circumstances where strict compliance with sections 933 or 934 of this title is not feasible, would be unreasonably expensive, would unreasonably affect public trust uses, or would result in the waste or unreasonable use of water, a diverter may submit an alternative compliance plan.

(b) Minimum Standards – an alternative compliance plan under subdivision (a) shall meet the following minimum standards:

(1) The plan shall include the following information:

(A) The name and contact information for all diverters covered by the plan;
(B) The name and contact information for the person designated to represent all diverters covered by the plan in matters before the board;
(C) Identification of each individual water right type and priority covered by the plan;
(D) A detailed description of the area served by the plan, including all points of diversion whether used or not used, all methods of diversion, any conveyance systems, all beneficial uses of water, and all acreage served;
(E) The assessor’s parcel numbers and ownership within the area covered by the plan;
(F) Identification of the proposed measurement frequency;
(G) Identification of the proposed measurement methodology;
(H) Topographic map(s) or aerial photograph(s) of the area covered by the plan that show the separate places of use authorized to be served by claimed water rights covered by the plan and showing the acreage served;
(I) An implementation schedule, including date-specific, objective milestones of plan implementation from date of filing through final implementation, including the estimated milestones for acquiring permits required for plan implementation and the estimated milestones for compliance with the California Environmental Quality Act, if required;
(J) Budget for implementation of the plan and the source(s) of financing for the plan;
(K) A list of any permits required for plan implementation, the agencies that will issue the permits, and expected dates for issuance;
(L)
An affirmation, signed by all diverters covered by the plan, that the plan will be implemented in accordance with the schedule contained therein and that all claimed water rights covered by the plan will not be exercised outside the scope of the plan  …………”

## How Do I Comply With Water Board Regulations? Part 2

In Part 1, How Do I Comply With Water Board Regulations? , we looked at what water flow measurement devices will meet and exceed the Board’s requirements.  The questions right back to me were:  1) Yeah, but which dates apply to me?  and 2) Yeah, but what about monitoring and collecting data and reporting?  How do I do that?

1.  Who has to have a certified, accurate device by January 1, 2017?  How often is it monitored?

This is the “worst case” if I am not already compliant – less than 6 months from today!  The first to have to report are those who divert 1,000 acre-feet or more per year, or store 1,000 acre-feet or more per year.  The reporting has to be hourly, or 8,760 data points per year.  The average rate of diversion for 365 days is 1.38 cubic feet per second (cfs) (which I had rounded to 1.40 cfs in previous posts).  That’s equal to 620 gallons per minute (gpm), or 2.74 AF/day.

What if all the flow is diverted just for the irrigation season?  Let’s use 6 months for simplicity – the average rate of flow is 2.76 cfs.  Available flows drop as the summer proceeds, so what size of water right are we really looking at?  Let’s say flows decline evenly from 100% at the beginning, to 50% of available flows at the end of 6 months.  The right that would divert 1,000 AF per year under these conditions is 3.68 cfs.  The summary is, if my water right is, say, 4 cfs or more, then it is very likely I will be in this category.  The weir shown above is a 4′ weir, capable of measuring up to 4 cfs very accurately, at plus or minus 5% (sometimes better) accuracy with new lumber.  A headgate like the one to the left is easily capable of passing 4 cfs and, if the gate is used as a measurement orifice, the accuracy can be 5%, certainly within plus or minus 10% if care is used with an older gate.

I can get that 4′ weir shown above installed and working for somewhere between \$2,000 and \$10,000 – depending on how difficult the access is to the site, whether native materials can be used, or 3/4″ base rock and 12″ protective rock have to be hauled in, and whether I already have a backhoe or excavator to install it.  The headgate will cost more than that, maybe \$3,000 to \$12,000.  A larger bulkhead or box is required, and good gates can cost quite a bit.

A larger diversion will have to use a larger weir or orifice, or more likely a flume or acoustic measurement device.  That makes sense – the larger the flow, the more complicated it is to measure.

How do I report hourly flows?  I sure can’t run out to the diversion every hour, so that means I have to use some kind of automated flow measurement device.  The G.E. Panametrics acoustic Doppler meter on the left is an option, and it or an in-line propeller meter, or an inline mag-meter, will be necessary for some configurations of diversions (pumped or very flat).  The price starts at \$5,000, though.  If I have enough fall (drop in water elevation), I would sure rather put in a weir, orifice, or flume.  A weir or flume can use a water level measurement device and data collector like the water level logger above on the right.  That Global Water device is relatively durable, takes readings as often as desired, and can store data for months.  It costs a little over \$1,000.  Oh, and if the orifice is submerged, so that the hole is underwater both upstream and downstream, then I will need two water level loggers, for \$2,000.

Some folks at the Water Board are talking about telemetered data, meaning the data is sent to a remote location, or even available online.  This would only be necessary if there were a great possibility that the diversion would be tampered with, or if it is a large diversion having a big impact on the amount of flow left in the stream.  This has little benefit for anyone at most diversions.  I would only install it if the need were very clear to me and everyone else.  The added cost can be anywhere from \$1,000 for short-range radio, to \$20,000 or more for a full-on gaging station like you see on streams.  The annual cost of operation and maintenance goes up, too.

How do I read the data on these devices, so I can report it to the Water Board?  Well, that takes some expertise.  If I have 5 diversions from a creek, I’ll make sure my foreman knows how to do it, and handle it myself.  If I have 1 or 2 diversions, then it’s more cost effective for me to have a professional do it, and to maintain it periodically.  Reading that data takes a laptop to hook up to the USB port, and the software that comes with the device, and the expertise to look at the data and make sure it’s reasonable.  The data that is recorded is “stage”, or water surface elevation.  Using the correct weir, orifice, or flume equation, or table from the Water Measurement Manual, the stages have to be converted to flows.  For hourly flows, that means 8,760 data points per year, which will require a spreadsheet like Excel to make the conversions.  A BIG caution is that if the boards are changed, it has to be written down and then a different zero-flow datum used to convert stages to flows starting when the change was made.

2.  Who has to have a certified, accurate device by July 1, 2017?  How often is it reported?

The “next worst case” is for those diversions from 100 AF to 1,000 AF per year – irrigation water rights of about 0.35 to 3.5 cfs.  These have to be recorded daily.  The measurement devices are the same, but smaller.  It is possible someone might grab a reading every day…but it is more likely that these will also have some kind of automated water level logger.  More on these later.  Have a great weekend!

## How Do I Comply With Water Board Regulations? Part 1

Yesterday I met with some nice folks up in Hat Creek and Old Station.  A big question right now is, how do I comply with Water Board regulations?  Also, what exactly do I need to do for a measuring device?  And, where can I find out that what I do will be acceptable, so I don’t get dinged after I did what I was supposed to?

First: devices.  The most common, long-lasting, and cost effective devices for measurement of irrigation diversions are:  weirs, orifices, flumes, mag-meters, propeller meters, and acoustic Dopplers.

Weirs are the least expensive, long-lasting, accurate devices.  This weir was prefabricated and shipped from Briggs Manufacturing.  Installation takes a few hours, and with new 2″ lumber, accuracy is plus or minus 5 %.  That is better than the Water Board’s requirement of 10 % accuracy.

An orifice is often exactly the same as a weir, with the boards set as an orifice.  Instead of the water going over, it goes through an exactly-sized hole.  The accuracy is plus or minus 5 % if it is set up carefully.  The cost is the same as for installing and operating a weir.

Here is another kind of orifice – a headgate.  If it is a square headgate, or a new, round (Waterman) headgate, then the area of the opening can be determined with plus or minus 5% accuracy.  An older headgate or one with a less-than-perfect opening can still be 10% accurate, within the Boards’s standards.

This is a Parshall flume.  It uses no boards, so no debris can pile up.  It is nearly maintenance-free.  Flumes cost more to install, and if they settle and get out of level they lose accuracy.  However, you’ll see many of these in Northern California.  There are some prefabricated flumes just coming into production that will be easier to install and will include data collectors.

How do you know which one will work for a particular diversion?  Someone with expertise can check the ditch, grade, soil-type, flow range, and other information and tell you within a couple of days what will work best, with an engineering report and cost estimate.  Rights To Water Engineering does this for \$300 to \$500, and can install the device if you like, with an operations manual.

Filing Statements of Use with the Water Board is now all by computer through the Internet.  That’s one of the things Rights To Water Engineering, and some other folks do at a reasonable cost.  If that’s your worry then contact us and we can point you in the right direction or help you out with reporting.

This is the quick summary on compliance!  Contact me at (530) 526-0134 or RightsToWaterEng1@gmail.com, and read this blog for more detailed information.  Have a great weekend!

## Level , Seal, and Replace for Accurate Flow Measurements

Build measurement devices level, leak-proof outside and at boards inside, and replace old boards for accurate flows and to avoid fines for noncompliance.

Some operational considerations for flow measurements are the same as for your house.  When it was built, the foundation was made level.  Sure there can be transitions – changes in level where steps will be built – but the whole foundation had to be perpendicular to gravity.  Otherwise, the whole house would be tilted, nothing would fit together correctly, doors would not swing easily, windows might get stuck open, or worse.

It’s the same when measuring flow.  For any manually-measured device, like a weir, orifice, or flume, structures have to be installed level and replaced when they are no longer level.  More particularly for this discussion, weir and orifice boards must be level.  If the bottom of the weir box is not level, some adjustment can be made with the bottom board so that the top board is level.

A house is sealed against the weather, so air doesn’t blow through the cracks and water can’t leak inside the house.  If roof shingles come loose, the damage may cost hundreds of dollars by the time the ceiling shows a wet spot.

Weirs, orifices, flumes, or any other device cannot leak around the edges.  Otherwise some flow is not measured – so the reported diverted amount would be less than the amountactually going past.  Inside the device, the boards have to be sealed.  They might be sealed with plastic and gravel, as shown below, or just well-fitted.  If the soil is sandy, it is easy to dump shovelfuls of sand along the backs of the boards until the sand fills the cracks.  As long as the boards are not changed out, they will stay sealed for the season.

Boards wear out, too.  Fortunately, lumber is inexpensive for the few boards needed in a weir or orifice.  They should be replaced each year, or every 2 years at the most.  Everyone knows why – boards warp, shrink, twist, and otherwise change so they won’t fit welltogether anymore.  Besides fit, an old board can’t be leveled; one end will be level but the other end will not because of the warp or twist.

All of these considerations might seem like common sense, but 2/3 of diversions out in the field fail in at least one of these 3 tests.  Maintenance and replacement of measurement devices is not fun, but it’s like a house.  If a home is not built level and leak-proof, and rotted wood replaced, then damage only gets worse faster so it’s not a nice place to live.  In the case of surface water diversions in California, not only do these factors affect flow measurement, but they can affect compliance with the law, make neighbors upset, and possibly incur fines for inaccurate devices or misreported flows.

## Demo Measuring Weir and Orifice; & Who To Call At The Board?

#### Simple to set up weirs and orifices

Last time, on January 16, we looked at how to set up weir and orifice boards in a dry diversion.  This is more exciting – now we’re actually measuring flow over a weir and through an orifice!

Standing in front of the Wigno Weir, getting ready to “stick the weir” with an engineering ruler.  The ruler has inches on one side and tenths and hundredths of a foot on the other side – which is how engineers and surveyors measure the world in English (non-metric) units.

Sticking the weir with the ruler face-on shows that the depth is 0.31′, the same as the depth in the upstream pool.  The weir is 3.30′ wide and is suppressed or flat-sided – the water does not have to turn the corner while going over the weir.

With these measurements in hand, it’s a quick calculation using the suppressed weir equation:

to find 1.90 cfs.

Here is the same weir, before being set up with orifice boards.  Flow is measured through a hole instead of over the top of the boards

The same engineering ruler is used, but this time measuring from the center of the hole, up to the top of the upstream water surface.

Actually, it’s easier to measurefrom the bottom of the hole and subtract off half the height of the hole.  The hole is 1.00′ wide, 0.30′ high, and the water height is 0.25′.

This time, the flow is less, at 0.73 cfs, using the equation:   WHY?  I did not wait the 5 minutes it would take for the upstream head to stabilize.  It was cold and about to get dark and the videographer was patient but getting cold.  🙂

A question I hear all the time is, “Hey, I got this letter from the ‘State Water Resources Control Board‘.  What am I supposed to do about measuring my flow?  How do I keep from getting in trouble?”  The main number for the Water Board is (916) 341-5300 – and these folks have much more work to do than time to do it.  Several calls may be required to reach a knowledgeable person who isn’t already talking to two telephone calls, or making three investigations in the field.  Since the most calls I get are about enforcement letters, calls, or visits from the Board, it’s probably most useful to have the phone numbers and emails from Enforcement Program Staff.  Here they are, from:

http://www.waterboards.ca.gov/waterrights/water_issues/programs/enforcement/compliance/

## Enforcement Program Staff

Katherine Mrowka, Manager
(916) 341-5363
Kathy.Mrowka@waterboards.ca.gov