Tag: devices

Do Something Wrong, Instead Of Nothing Right

Do something wrong, rather than nothing at all. Have you ever heard that before? I have heard it from Army veterans, a boss, even an elder of a church.  George Patton said, “A good plan violently executed now is better than a perfect plan executed next week.”  A non-military way to say that is, “A poor plan now is better than no plan at all.”

What it means to you and me is, if action is necessary, do something, maybe ANYthing, rather than freezing in place or ignoring a problem. This is obvious when you see a tornado 5 miles away, for example; either drive away from it if you are in a car, or take shelter if you are on foot. If you have a plumbing leak in the house and no parts to replace broken pipe, then put a bucket under it, or turn off the valve, and call a plumber. All of us have seen a TV show (or maybe had it happen to us) where the bad guy pointed a rifle and said, “Don’t move”. What do we all say to the TV? “Don’t just stand there, run!”. Doing nothing is a much worse choice, if the result for freezing in place is death or injury.

What about water rights – how does doing something wrong help? Everyone knows by now that surface water diverters need measurement devices, so put in a weir box and boards and measure your flow before the threats come from the Water Board, your watermaster, your ditch tender, or your neighbor.  Even just stick horizontal boards in a ditch and seal the sides with plastic – something to take positive action to reduce future pain.

Remember to file the information for the measurement device with the Water Board, either via your annual report of diversions, or using the Water Right Form and Survey Submittal Portal.

Take a look at the blog posts below.  There is enough information and how-to directions, that you should be able to do it well enough to satisfy the Water Board.  Check out these posts:

There is a philosophy based in law and a lot of experience, that says don’t put any controls on yourself until the court or government makes

Temporary Weir In Ditch

you. Why remodel your house to accommodate the wiring or plumbing, if you aren’t selling the house and everything works okay right now? Who would put a lot of money into an old truck to make it pass smog, if it just might pass a smog check the next time it has to be done? What farmer would change how he irrigates or ranches if everything still operates and the bank will keep making operating loans?

All of the Water Board deadlines have passed to install measurement devices, or file Alternative Compliance Plans.  If you haven’t got your device or plan done yet, get a Request For Additional Time done as soon as possible.

Be proactive.  Take some inexpensive, temporary action.  Educate yourself for free with some time in the Internet. Even a small, less-than-perfect improvement in your measurement device, flow and water use record keeping, can pay back a lot more when you have to deal with potential Water Board fines, a court case, or even just an angry neighbor in the future.

Do Something Wrong, Instead Of Nothing Right

Do something wrong, rather than nothing at all. Have you ever heard that before? I have heard it from Army veterans, a boss, even an elder of a church.  George Patton said, “A good plan violently executed now is better than a perfect plan executed next week.”  A non-military way to say that is, “A poor plan now is better than no plan at all.”

What it means to you and me is, if action is necessary, do something, maybe ANYthing, rather than freezing in place or ignoring a problem. This is obvious when you see a tornado 5 miles away, for example; either drive away from it if you are in a car, or take shelter if you are on foot. If you have a plumbing leak in the house and no parts to replace broken pipe, then put a bucket under it, or turn off the valve, and call a plumber. All of us have seen a TV show (or maybe had it happen to us) where the bad guy pointed a rifle and said, “Don’t move”. What do we all say to the TV? “Don’t just stand there, run!”. Doing nothing is a much worse choice, if the result for freezing in place is death or injury.

Ready-to-install 3-inch Montana Cutthroat Flume

What about water rights – how does doing something wrong help? Everyone knows by now that surface water diverters need measurement devices, so put in a weir box and boards and measure your flow before the threats come from the Water Board, your watermaster, your ditch tender, or your neighbor.  Even just stick horizontal boards in a ditch and seal the sides with plastic – something to take positive action to reduce future pain.

Remember to file the information for the measurement device with the Water Board, either via your annual report of diversions, or using the Water Right Form and Survey Submittal Portal.

Take a look at the blog posts below.  There is enough information and how-to directions, that you should be able to do it well enough to satisfy the Water Board.  Check out these posts:

There is a philosophy based in law and a lot of experience, that says don’t put any controls on yourself until the court or government makes

Temporary Weir In Ditch

you. Why remodel your house to accommodate the wiring or plumbing, if you aren’t selling the house and everything works okay right now? Who would put a lot of money into an old truck to make it pass smog, if it just might pass a smog check the next time it has to be done? What farmer would change how he irrigates or ranches if everything still operates and the bank will keep making operating loans?

All of the Water Board deadlines have passed to install measurement devices, or file Alternative Compliance Plans.  If you haven’t got your device or plan done yet, get a Request For Additional Time done as soon as possible.

Be proactive.  Take some inexpensive, temporary action.  Educate yourself for free with some time in the Internet. Even a small, less-than-perfect improvement in your measurement device, flow and water use record keeping, can pay back a lot more when you have to deal with potential Water Board fines, a court case, or even just an angry neighbor in the future.

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/Repost] Do Something Wrong, Instead Of Nothing!

Do something wrong, rather than nothing at all. Have you ever heard that before? I have heard it from Army veteran friends, a boss, even an elder of a church.

What it means to you and me is, if action is necessary, do something, maybe ANYthing, rather than freezing in place or ignoring a problem. This is obvious when you see a tornado 5 miles away, for example; either drive away from it if you are in a car, or take shelter if you are on foot. If you have a plumbing leak in the house and no parts to replace broken pipe, then put a bucket under it, or turn off the valve, and call a plumber. All of us have seen a TV show (or maybe had it happen to us) where a bad guy or an enemy pointed a rifle and said, “Don’t move.”. What do we all say to the TV? “Don’t just stand there, run!”. Doing nothing is a much worse choice!

What about water rights – how does doing something wrong help? Everyone knows by now that surface water diverters need measurement devices, so put in a weir box and boards and try to measure flow if the Water Board, your watermaster, or your neighbor is promising painful consequences. Even stick boards in a ditch and seal the sides with gravel – something to take positive action to reduce future pain.

Take a look at the blog posts here.  There is enough information and how-to directions, that you might be able to do it right!  Check out these posts:

There is a philosophy based in law and a lot of experience, that says don’t put any controls on yourself until the court or government makes you. Why remodel your house to accommodate the wiring or plumbing, if you aren’t selling the house and everything works okay? Who would put a lot of money into an old truck to make it pass smog, if it just might pass a smog check the next time it has to be done? What farmer would change how he irrigates or ranches if everything still operates and the bank will keep making operating loans?

Surface water and groundwater are getting 10 50 times the attention they were prior to 2009. If the Water Board, or California Fish and Wildlife, or any other agency comes along, do something, anything, to comply sooner, even if it’s not the ultimate solution. Two posts ago, bureaucrats were discussed – they are still human beings and most people appreciate some effort to “get with the program”.

Be proactive, take some inexpensive action, educate yourself for free with some time in the Internet. Even a small, less-than-perfect improvement in your measurement device, flow and water use record keeping, diversion practices, or acreening, can pay back a lot more when you have to deal with agencies, a court, or an angry neighbor in the future.

Do Something Wrong, Instead Of Nothing!

Do something wrong, rather than nothing at all. Have you ever heard that before? I have heard it from Army veteran friends, a boss, even an elder of a church.

What it means to you and me is, if action is necessary, do something, maybe ANYthing, rather than freezing in place or ignoring a problem. This is obvious when you see a tornado 5 miles away, for example; either drive away from it if you are in a car, or take shelter if you are on foot. If you have a plumbing leak in the house and no parts to replace broken pipe, then put a bucket under it, or turn off the valve, and call a plumber. All of us have seen a TV show (or maybe had it happen to us) where a bad guy or an enemy pointed a rifle and said, “Don’t move.”. What do we all say to the TV? “Don’t just stand there, run!”. Doing nothing is a much worse choice!

What about water rights – how does doing something wrong help? Everyone knows by now that surface water diverters need measurement devices, so put in a weir box and boards and try to measure flow if the Water Board, your watermaster, or your neighbor is promising painful consequences. Even stick boards in a ditch and seal the sides with gravel – something to take positive action to reduce future pain.

There is a philosophy based in law and a lot of experience, that says don’t put any controls on yourself until the court or government makes you. Why remodel your house to accommodate the wiring or plumbing, if you aren’t selling the house and everything works okay? Who would put a lot of money into an old truck to make it pass smog, if it just might pass a smog check the next time it has to be done? What farmer would change how he irrigates or ranches if everything still operates and the bank will keep making operating loans?

Surface water and groundwater are getting 10 times the attention they were prior to 2009. If the Water Board, or California Fish and Wildlife, or any other agency comes along, do something, anything, to comply sooner, even if it’s not the ultimate solution. Two posts ago, bureaucrats were discussed – they are still human beings and most people appreciate some effort to “get with the program”.

Be proactive, take some inexpensive action, educate yourself for free with some time in the Internet. Even a small, less-than-perfect improvement in your measurement device, flow and water use record keeping, diversion practices, or acreening, can pay back a lot more when you have to deal with agencies, a court, or an angry neighbor in the future.

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
the 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.

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.

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.