Solving Diverters' Headaches To Provide Peace Of Mind And Help Stay Out Of Trouble
Category: Accurate, Lasting Devices
There are standard measurement devices on the lower end of cost: weirs, orifices, and flumes. They can be easily purchased pre-fabricated, saving you time and money. Accuracy and speed of measurement make these great for reporting and for defending your diversion against challenges. High tech options like acoustic Dopplers, magnetic meters, and propeller meters cost more but save time for larger diversions. All are good to +/- 5% or better when installed, easily meeting any standard for field measurements.
How are water pressure logger measurements converted to diverted flows or reservoir storage? Why does anyone even have to have an electronic pressure logger? PMC, Onset Computer, In-Situ, , and other manufacturers sell data loggers and water level loggers, not pressure loggers, so why is this post talking about measuring pressures at all?
Most “loggers” record pressure, because that is the easiest physical attribute to measure. A data logger in water does not know how deep it is, and it does not know how much flow is going by, or how much water is being stored in a
reservoir. Pressures relate directly to static (standing) water depths, and then equations convert the depths to flows, or to reservoir storage volumes.
How is pressure converted to depth? It’s an easy calculation – water that is one foot deep has a pressure of 0.4335 psi at the bottom. So, if your logger measures 7.00 psi, then the calculation to get depth is 7.00 psi / 0.4335 psi per foot = 16.15 feet of depth.
Now that you can calculate any depth, how do you convert depths to reservoir storage? That requires an Area-Capacity curve, also known as an Elevation-Storage curve. The points can be picked off the curve. For example, in the curve below, a depth of 8.5 feet would correspond to an elevation of 2,802.5 feet, and a reservoir storage volume of 30 acre-feet.
An owner of a reservoir with a capacity over 10 acre-feet must collect monthly storage values. That’s easily done by hand. However, a reservoir with a capacity of 50 AF requires weekly measurement; over 200 AF requires daily measurement; and over 1,000 AF requires hourly measurement. That is really tedious to do by hand.
This is where an Excel spreadsheet can make the task a whole lot easier! The spreadsheets shown below are just for this. The first sheet helps translate a graph into a table of elevations and storage volumes. The second sheet translates collected pressure values into depth and storage values, for as many data points as needed.
How are pressures converted to flows? The logger is in a stilling well, usually a pipe connected to the inside or outside wall of the weir, flume, or orifice. It measures pressure, which is easily converted to depths.
As with reservoirs, Excel spreadsheets make the conversion process a whole lot easier. The sheets below have the rating curve for a suppressed weir, and the second sheet converts pressure to actual water depths over the weir boards. Even for thousands of hourly readings, the hourly flow volumes are quickly calculated and are ready to send to the Water Board:
I have talked to a few hundred people about reservoirs over the last year. How is a reservoir different from a pond? What size has to be measured? If you have a reservoir, how do you measure it? Can a 15 acre-foot pond be measured the same way as a 1,500 acre-foot reservoir? I have been estimating the storage for years, can’t I just keep doing that?
A reservoir is man-made, and may or may not have a pipe outlet. “Pond” is a more general term and does not signify whether the body of water is natural or man-made. Reservoirs include everything from less than 1 acre-foot stock ponds with a dam a few feet high, to Shasta Reservoir (Lake Shasta).
Every reservoir over 10 acre-feet has to have its storage volume measured monthly or more often, up to hourly for 1,000 acre-foot and larger reservoirs. How is that done? We’ll get to that in a few paragraphs. Here is the table from theWater Boardthat specifies diversion amounts, storage amounts, compliance deadlines, accuracy, monitoring frequency, and who can do the work. Personal gripe: Hey, Water Board web design folks, your web pages are dang hard to see for folks that are over 50! I had to modify the screenshot just so folks can see the rows and columns.
NOTE: if you take the new class that the U.C. is putting together, you can install and certify your own measurement device(s)!
How can you comply, and what has to be done? There are thousands, or tens of thousands of ways considering every permutation of each option, but I am going to list the four main ones that I use, from cheapest to most expensive:
Alternative Compliance Plan– This is doing something besides standard compliance and still coming up with accurate-enough storage values at thePond – photo credit: publicdomainfiles.com
necessary frequency. Within an ACP are thousands of possibilities, but the simplest case is a 10 acre-foot reservoir 3 driving hours away from the ranch house or first gate, not accessible in the winter. An ACP for this often boils down to this: it is a landscape feature, no action of man is needed to fill or drain it, livestock and wildlife rely on it, it takes most of a day to get there and back, and a data collector is likely to get stomped on if cattle or elk can ever get to it. This is the “I’m just going to keep estimating it and that meets everyone’s needs” option, and I think it is valid in a fair number of cases. Just see some of the ACPs I have filed. An ACP is harder to justify at the large end of reservoirs, but it might include things like occasional drone flights, usingCIMIS data for evaporation, perhaps only measuring the outlet some distance downstream of the reservoir while estimating storage, and so on.
Run a tape measure or long plastic tape from the edge of the dam road, down to the water’s edge, once a month or whatever the necessary frequency is. This requires getting the inspection report, or at least the area-capacity curve from the Water Board. You need two pieces of information: the slope of the water-side dam surface, and the storage volume at a few intervals of depth. Most small reservoirs that I have seen have a water-side dam slope of 3 feet horizontally to 1 foot vertically. Area-capacity curves can vary, and in the rare case where the Water Boardor theDivision of Safety of Damsdoes not have a curve, you’ll need to do a survey of some depths to generate contours and make the curve.
Install staff gages. This involves driving or setting lengths of 2″ galvanized pipe that overlap vertically with the next pipe up-slope or down-slope. Then 2″ x 6″ lumber and 3′ or longer gages are bolted to the pipe, using a survey level to make sure the 5-foot mark, for example, at the top of one gage matches the 5′ mark at the bottom of the next-higher gage. This can cost a few hundred or a few thousand dollars, depending on how much work you do vs. hiring work out, access, depth of the reservoir, and so on. Oregon Ruleis one good company to get the staff gages.
Install water level loggers to collect pressure data, and convert the data to depths, then to elevations, and then to storage volumes, after the data is downloaded. This is standard compliance. What if you don’t have power lines to the dam? There are many data loggers that run on batteries, for times of 2 years up to 12 years. I mostly use the Onset HoboandPMC Versalinewater level loggers. Hobos are put in protective, short PVC lengths, with a moderate weight, a rope, and buoy, and then setting them at the deepest part of the reservoir using a boat. Data is downloaded by boating out, hauling up the Hobo, and putting it back in the same place. This is easy if a heavy weight is attached by a second rope to the same or a different buoy to keep the location constant. The PMC Versaline keeps the data collector on shore, with a cable to the water level logger. It is installed in whatever length of PVC pipe is needed to get from the dam at a point above where any water gets, down to the logger end. Then, no boat is needed to download data. Which option is better? See some of my earlier posts on the specifics of water level loggers.
Those are brief explanations, but you can find the detail in earlier posts on my blog, and some other blogs. Does this help you? Please let me know, whether yes, no or maybe!
This summer has been busy! Posts here have fallen behind as I have been keeping up with clients’ needs for SB 88 compliance.
I am taking just a moment to mention the new Watchman Flumes. A new manufacturer is making these heavy-duty flumes tough enough that cattle could step on one or rub against it and probably not bend it.
10-gauge steel is used, slightly thicker than 1/8″. The walls and ramps are heavily reinforced with 1/8″ angle-iron and high-strength Grade 8 bolts to minimize flexing and bending. Back-filling these flumes will not bend the walls or wingwalls, even when using concrete for fill.
Watchman Flumes are delivered disassembled with all the fasteners. At this time the manufacturer is only selling through Rights To Water Engineering, but that may change in the future.
Sizes range from 2 to 60 cubic feet per second. The flumes are accurate to better than +/- 5%, which is well within the Water Board’s requirement of +/- 10% for new measurement devices.
These are priced competitively with pre-manufactured flumes for similar flows, too. That makes higher durability and longer life at the same price as flumes made from 1/16″ sheet metal.
Expect to see more of these going in at diversions around Northern and Central California. I will post photos of installations as I get permission from landowners.
I am glad to be getting measuring devices and data loggers installed – it is enjoyable work and diverters are getting peace of mind. All of my work is confidential so clients’ names won’t be mentioned without permission. That being said, a few projects can be discussed here.
This is a unique weir installation – it is doing two things at once. Two 4′ wide weirs are side by side, set on a leveled, compacted base of 3/4″ minus road base.
First, it has a splitter built in as part of the weir – see the low wall behind me. Two water rights are precisely split inside the weir itself so each user gets the correct amount.
Second, it is a double weir. The ditch has low banks, but around 10 cfs needs to be accurately measured. Weirs ideally pass a maximum of 1 cfs per foot of width, so this exceeds that by 25%, while still keeping the water inside the ditch. So, why use weirs instead of a flume, which can pass much more flow per foot of width? Weirs are better understood in this area, the ditch has adequate width, and it makes splitting the flows easier.
A plate metal wall splits the 2 weirs into 3. Board slots were added with angle iron…you can guess from the photo that the iron lengths had to be cut down a bit for a 1-board, 2″ x 12″ weir.
Board slots had to be bolted on both sides of the plate steel. My friend Bob, owner of B & J Welding & Machine, Inc. in Anderson, cut, welded and drilled the plate steel wall.
A water level logger sits at the back of the shared weir walls, and records hourly water levels 24 x 7 x 365. Vandalism is a concern so the logger is locked up, and only the owner and I can get in.
1/4″ thick plate metal wingwalls upstream and downstream protect against flow working its way around the sides. The wingwalls add stability, keeping the weirs from tipping sideways or tilting up- or downstream.
The final result is s solid, long-lasting installation that meets the requirements of SB 88!
Recording is the other half of measuring diversions from streams, under the law per SB 88, and per the Water Board‘s water diversion measurement and reporting regulations. Diverters are required by law to measure flows at frequencies based on the volume of water diverted in a year. The flow has to be measured and recorded. Of course many diverters don’t need the data – it costs money and it doesn’t add income…unless a farm or ranch is upgrading for efficiency or to increase acreage What you and I want in all of our purchases is the best value for the money.
We’ll look at 5 different water level logging options. The total cost given does not include installation – that adds $200 and up. Certification for the logger and the measurement device itself, by a professional, required for all but the smallest diversions, costs $300 and up if you have Rights To Water Engineering do the work.
Vegetronix Aqua-Plumb Water Level Sensor connected with the Logger-8-USB ($400 per diversion, less if diversions are very close to one another – with tax and shipping, about $500 per diversion)
Onset Hobo U20L-04 Water Level Logger ($600, less for multiple diversions; with tax, shipping, and data shuttle, about $1,050 for the one diversion, $1,400 for two….)
Global Water WL-16 ($1,000; with with tax, shipping, and cable, about $1,450 per diversion)
In-Situ Rugged Troll 200 Data Loggerand Tube 300 Telemetry System ($1,200 – less for multiple diversions, plus $1,300 for each telemetered diversion. With tax, shipping, and cable, about $1,600 per diversion, and with telemetry and add-ons, about $3,300 for one diversion)
PMC Versaline VL4511 – WLS-31 ($1,370 per diversion; with the cable, tax, and shipping, about $1,800 per diversion)
This is a long post since it is hard to summarize something this technical so here isthe bottom line: my top recommendation is the last of five in this post – for most diverters.
SWRCB Measurement and Recording Requirements for 2017 (diverters exempted where Watermaster reports)
For very small diversions, flows have to be recorded monthly or weekly. That is easy to do as long as someone goes to the diversion at least once a week.
Photo credit: globalw.com
For medium-sized diversions, flows must be recorded daily. This is possible, but it doesn’t allow for the owner or employees to have time off, travel, and so on. At this level of recording, an automatic recorder of some type is necessary. Large diversions must be recorded hourly, and automatic recording is the only practical way to be sure flows are recorded.That is the subject of today’s post: automatic recording of flows, or what is really done most of the time, recording water levels and using equations to calculate the flow.
We will leave aside the discussion of propeller, acoustic Doppler, magnetic, and other in-line meters. If you have a diversion that goes through a long length of straight pipe, one of these devices can be bolted in or strapped on. This post is about open diversions into a ditch, where an instantaneous measurement device (weir, orifice, flume) already exists. These open devices do not measure flow directly, they measure the water level. An equation is used to convert levels to flows after data is downloaded.
There are hundreds of devices (ready to go) and components (connected parts) to measure water levels. There are also hundreds of loggers that collect data. Here, we will look at 5 water level sensors connected to data loggers, called water level loggers.
THE FIRST is a setup that rancher and retired aircraft engineer Frank Crowe has been working on. Frank’s desire is to save him and his neighbors money, so he has been working with theVegetronixAqua-PlumbWater Level Sensor connected with theLogger-8-USB. Together these are $340, which is
the least cost of anything that I have seen. With this you will have all the
parts you need for moderately durable, reliable, and accurate water level logger. Not only that, but the Logger-8-USB has 8 channels altogether, so a diverter could measure up to 8 water levels at once by adding 7 more sensors at $95 apiece. Wiith tax and shipping, this costs about $500 per diversion)
Here is Frank’s latest setup with his comments: “Finally was able to put together a prototype package for the Vegetronix sensor. The box is a little bigger than needed, but seems to work. I’m trying to get the data to download into something I can analyze, but it seems to work very stable.
The pipe is 3/4″ mounted to the box, with the sensor wire going down to about an inch from the bottom and then returns up over 12″, therefore doubling the sensitivity. The end is held by some wire at the moment, but would probably work better with a stainless steel spring. The top of the pipe is not sealed, but should be to keep the humidity out of the box. Of course if the data logger were in a separate box, the seal would not be necessary.
To exercise the thing, it is stuck into a 3″ pipe with a water drip going in and a drain at the bottom. The overflow hole is 13″ above the bottom.”
So, what is the trade-off? If you are handy, somewhat experienced with electronic components, and willing to spend some hours, you can set this up yourself. Frank can help a few of his neighbors, but he has his family and ranch requiring his time, too. Otherwise, it is going to cost a couple hundred dollars or so for someone to set this up for you. It needs to be checked, maintained, and adjusted more often than the integrated water level loggers, too, so the maintenance and downloading cost can be $50 to $100 per year if everything is working well.
SECOND, theOnset Hobo U20L-04 Water Level Loggeris $300 before shipping and tax. The DWR Groundwater folks I worked with for years, use these in groundwater wells. They are easy to set up – program one and place it in a stilling well. Take it out once or twice a year to download the data. The battery life is 5 years, maybe more.
Why aren’t these automatically the cheapest option?They may be the cheapest if a diverter has 3 diversions or more, or several neighbors are using the same Hobo U20L-04.However, they are not vented, meaning that as atmospheric pressure changes due to low pressure areas and storms, the device’s pressure reading will not be as accurate. Therefore Onset recommends having a second U20L-04 set up outside the water to measure the pressure change over time. The second device can be some miles away, so one outside calibration device could be used for several in the water within a 300-square-mile area.
What I heard from colleagues is that these did not last for 10 years, and sometimes not for five years, although the device is being improved over time. Durability and reliability of a device are important for uninterrupted data, and therefore compliance with the Water Board’s regulations. The more often a device has to be replaced, the more it costs over time.
In summary, the cost of Onset Hobo U20L-04 devices is $600. This cost may be reduced somewhat if the cost of a calibration device can be shared between several diverters, or several diversions. With tax, shipping, and data shuttle, the delivered cost for all parts is about $1,050 for the one diversion, $1,400 for two….)
THE THIRD device discussed here is theGlobal Water WL-16. This is an integrated, vented device, designed to program and set in a pipe. Watermasters have used these for years at various diversions.
The WL-16 has a stainless steel casing and is fairly tough. They should last a good 5 years. The problem is at the sensor end – it is relatively easy to clog up in warm-water conditions, with algae and/or silt. In cool flowing water, it might operate for the whole irrigation season. In warmer or still water, it will have to be checked and sprayed clean every 1 to 3 months. Watermasters have put the sensor ends in distilled water in baby-bottle bags, and rubber-banded the tops of the bags closed to keep the sensors clean for the entire irrigation season.
One other concern which I have not discussed with the manufacturer – the manual for the WL-16 was updated in 2009 and refers to Windows XP, not the current Windows 10. I am sure that a newer manual is sent out with the device when it is purchased. Overall, with some care to check the sensor end and clean it as necessary, this is a great drop-it-in-and-turn-it-on option. The cost for a WL-16 is $1,000; with with tax, shipping, and cable, about $1,450 per diversion.
THE FOURTH device, the In-Situ Troll, has the advantage of out-of-the-box options for telemetry. The Groundwater folks at the Department of Water Resources have used these and a couple recommend these for the right application. The In-Situ
The Troll 200 Data Logger can run independently without telemetry, or be attached to the Tube 300R Telemetry System. The Troll 200 is non-vented, so like the Onset Hobo data loggers mentioned above, an extra unit is needed for air pressure to correct the water level (pressure) recorded by the unit in the water.
The total unit cost for 2 Troll 200s, a Tube 300R, and accessories, is about $2,900. This is not cheap, but it is a lot less than a full-on gaging station with satellite radio, which costs $12,000 and up for components, and over $2,000 to install in easy locations. Telemetry is expensive, there is no way of getting around that fact. In summary, the cost for 2Troll 200s is $1,200 to log a diversion – each additional, nearby diversion costs only another $600. Telemetry addes $1,300 to the cost of parts for each telemetered diversion. With tax, shipping, and cable, using Troll 200s costs about $1,600 per diversion, and with theTube 300Rtelemetry and add-ons, the total parts cost is about $3,500 for one diversion)
The Tube 300R requires a separate phone number for each water level logger, and cell service. In-Situ offers the option of $35/month web hosting, on its HydroVu Cloud Data Services Plan. This cost is in addition to the Tube 300R, cell phone service, and installation.
THE FIFTH and final water level logger discussed here is thePMC Versaline VL4511 – WLS-31Water Level Datalogger. This looks much like the WL-16, but instead of a silicon bladder at the end of sensor, it has a non-fouling ceramic sensor.At $1,370 before tax and shipping, it has the highest purchase cost of the 4 listed in this post, but it is my recommendation for durability, reliability, and low maintenance.
The Versaline is made for wastewater; in other words, for sewer lines. The datalogger end is vented and it is not supposed to be submerged, same as the Vegetronix components and the WL-16. However, it is made to put inside manholes where it is very warm and humid. The PMC guys have maintained the sensor end in rough environments with the equipment lasting 8 to 12 years. If the sensor gets completely covered with algae (or something worse), it still works. It can be cleaned off with a toothbrush if it seems so clogged it might prevent water from getting to the ceramic end. The data logger and sensor are fairly new but are improvements on the older, long-lived versions.
The VL4511 – WLS-31is three times the cost of the least-expensive option. However, it might be the least expensive in the long run…it sure is the most worry-free of all the options listed here! In summary, the VL4511 – WLS-31 costs about $1,370 per diversion; with the cable, tax, and shipping, about $1,800 per diversion.There are many, many choices for logging water levels. These are the ones I would install, either because I, my colleagues at DWR, or larger farms or ranches have used them; or because I have checked with other users. One of these choices can serve you well!
When you call and ask, “What do I have to do to stay out of trouble with the Water Board?”, my reply is usually, “What’s your diversion or pond like? How much and what type of water right(s) do you have? When can I come and take a look at it?” We’ll figure out a time, and I’ll visit for 2 hours or however long it takes to see how your diversion works, or how your pond fills and empties, and think of a few likely solutions.
Then I will write up an evaluation and proposal. The proposals are good enough that, if you don’t choose me to install or certify it, then you, another engineer, or a contractor knows how to get the job done can install it and keep you out of trouble. Of course, I would like the whole job, but you do have choices!
So, what does an evaluation and proposal look like? Here is an example, just for a single measurement device for one diversion:
In this post I am highlighting the McCrometer Mc Mag 3000 flow meter for pipelines. I don’t have a lot of detail here, so I will update this a couple of times before mid-February.
Most of the flow measurement devices I have talked about in this blog are for use in ditches, and include weirs, orifices, and flumes. These devices are the standard lower-cost devices that are relatively easy to install. All of these devices require a separate, specially installed data collector to record stage (water surface elevation) so flow can be computed from the data.
What if your flow already runs through a level length of pipe? You have many, many options from manufacturers. There are propellor, magnetic, and acoustic meters, with integrated data collectors, that bolt up or strap on. Most magnetic and acoustic meters require external power, but some run on batteries, and an increasing number have battery options. Within a few hours any full pipeline that is straight and level, and has 10 to 20 pipe diameters of straight pipe upstream of the meter, and 10 pipe diameters downstream of the meter, can have one of these devices installed and operating.
Note the “level and full” restriction – there are meters that can handle sloped and/or partly full pipelines, but they are more expensive. Usually it is less expensive to insert (or add to the end) a section of level pipeline that will always be full.
What do these cost? I have not asked about every possible pipe diameter, but I think the cost range for 4″ to 12″ pipes is around $1,400 to $3,000, before tax, shipping, and installation costs. That’s a reasonable price for a quick-to-install device that measure up to about 5 cfs in a 12″ pipe. McCrometer even has a “how-to” video on their website, for the physical part of the installation.
What if you have a larger pipeline? The SonTek-IQ may be a better solution – the pipe version of this flow meter and data logger can handle pipes as small as 18 inches in diameter, up to 16 feet (!). This is an acoustic Doppler meter, rather than magnetic sensing with the McMag 3000. There is an open channel version of the IQ, too, which installs in the bottom of a canal.
For larger or more irregular channels, Sontek-SL, which is a side-looking acoustic Doppler. the SonTek acoustic equipment is a costlier solution for small-diameter pipes – the cost range for the SonTek equipment is $8,200 to $9,200. For a larger pipe, canal, or natural channel up to 66 feet wide, this is a very cost-effective solution. We’ll talk more about the SonTek equipment in later posts.
Thank God for all the rain and snow! As of today, California is still having record rainfall and a near-record snowpack, through February 2. Have a good night, all.
If you divert over 1,000 acre-feet a year, or over about 4 cfs during the irrigation season, your measurement device deadline at the Water Board was January 1. However, you can file a Request For Additional Timeuntil 30 DAYS AFTER THE FORM IS AVAILABLE ONLINE. It is January 18 today, so the filing deadline has to be later than February 17, 2017. This is a welcome UPDATE from 10 days ago, when the Deadline was January 30.
I am often nervous about just mailing a letter or filling out a form online; the letter could fall off a table and the web-based form does not always work. You can always send an email to record your intent to make the request. This also helps in case you are unable to (or forget, with 99 other things on your to-do list) fill it out by the deadline. You will have a record that you are making the request and intend to fill out the form. Who should you email? See the post Update – Who To Call At The Board? for names, phone numbers, and email addresses.
See the second table below for the original deadline table, including approximate equivalent water rights. Let me know if you need help!
SWRCB Water Rights: Water Use Reports and Measurement webpage, January 18, 2017SWRCB Measurement and Recording Requirements for 2017 (diverters exempted where Watermaster reports)
My friend Steve Beall in the far north of the state brought something to my attention, regarding my comparison of four water level loggers (five with the In-Situ Troll 200 added). I listed only the component costs, and not the data cable, data shuttle (Hobo), software, PVC/galvanaized pipe, or installation. Good point, and thanks for suggesting that I address all costs, Steve. The five loggers detailed farther on down in the post are, with component costs only, data transfer, installation, and certification not included:
Vegetronix Aqua-Plumb Water Level Sensor connected with the Logger-8-USB ($400 per diversion, less if diversions are very close to one another – with tax and shipping, about $500 per diversion)
Onset Hobo U20L-04 Water Level Logger ($600, less for multiple diversions; with tax and shipping about $700)
Global Water WL-16 ($1,000 per diversion, about $1,100 with tax and shipping)
In-Situ Rugged Troll 200 Data Loggerand Tube 300 Telemetry System ($1,200 – less for multiple diversions, plus $1,300 for each telemetered diversion…about $2,500 for one diversion; with tax and shipping about $2,800 per diversion)
PMC Versaline VL4511 – WLS-31 ($1,370 per diversion, about $1,500 with tax and shipping)
The additional components you will need if you want to download and process your own data are: a customized data cable (or shuttle for the Hobo), and software. These add $250 to $350. You also need a laptop, except for the Hobo, unless you temporarily remove the other loggers to download them on your desktop at the house. Shipping and taxes will add $70 to $350, depending on which equipment and the location where it ships from. Electronic tools and equipment, and various testers are useful, sometimes necessary, to chase down problems. Extra connectors and wire might be needed – keep at least a simple kit. Installation can cost $200 and up, depending on the difficulty, need for vandalism protection, access, and so on. Certification by a professional, required for all but the smallest diversions, costs $300 to $500 if you have Rights To Water Engineering do the work.
***** ORIGINAL POST, with a couple of edits:
Recording is the other half of measuring diversions from streams, under California’s new water diversion measurement and reporting regulations. Diverters are required by law to measure flows at frequencies based on the volume of water diverted in a year. The flow has to be measured and recorded. Of course most diverters don’t care about the data – it costs money and it doesn’t add income…unless a farm or ranch is upgrading for efficiency or to increase acreage What you and I want in all of our purchases is the best value for the money.
This is a long post since it is hard to summarize something this technical so here isthe bottom line: my top recommendation is the last of five in this post – for most diverters.
SWRCB Measurement and Recording Requirements for 2017 (diverters exempted where Watermaster reports)
For very small diversions, flows have to be recorded monthly or weekly. That is easy to do as long as someone goes to the diversion at least once a week.
Photo credit: globalw.com
For medium-sized diversions, flows must be recorded daily. This is possible, but it doesn’t allow for the owner or employees to have time off, travel, and so on. At this level of recording, an automatic recorder of some type is necessary. Large diversions must be recorded hourly, and automatic recording is the only practical way to be sure flows are recorded.That is the subject of today’s post: automatic recording of flows, or what is really done most of the time, recording water levels and using equations to calculate the flow.
We will leave aside the discussion of propeller, acoustic Doppler, magnetic, and other in-line meters. If you have a diversion that goes through a long length of straight pipe, one of these devices can be bolted in or strapped on. This post is about open diversions into a ditch, where an instantaneous measurement device (weir, orifice, flume) already exists. These open devices do not measure flow directly, they measure the water level. An equation is used to convert levels to flows after data is downloaded.
There are hundreds of devices (ready to go) and components (connected parts) to measure water levels. There are also hundreds of loggers that collect data. Here, we will look at 5 water level sensors connected to data loggers, called water level loggers.
THE FIRST is a setup that rancher and retired aircraft engineer Frank Crowe has been working on. Frank’s desire is to save him and his neighbors money, so he has been working with theVegetronixAqua-PlumbWater Level Sensor connected with theLogger-8-USB. Together these are $340, which is
the least cost of anything that I have seen. Add shipping, tax,
and $60 in other parts and batteries, and for $450 you’ll have the parts you n
eed for moderately durable, reliable, and accurate water level logger. Not only that, but the Logger-8-USB has 8 channels altogether, so a diverter could measure up to 8 water levels at once by adding 7 more sensors at $95 apiece, not including tax and shipping.
Here is Frank’s latest setup with his comments: “Finally was able to put together a prototype package for the Vegetronix sensor. The box is a little bigger than needed, but seems to work. I’m trying to get the data to download into something I can analyze, but it seems to work very stable.
The pipe is 3/4″ mounted to the box, with the sensor wire going down to about an inch from the bottom and then returns up over 12″, therefore doubling the sensitivity. The end is held by some wire at the moment, but would probably work better with a stainless steel spring. The top of the pipe is not sealed, but should be to keep the humidity out of the box. Of course if the data logger were in a separate box, the seal would not be necessary.
To exercise the thing, it is stuck into a 3″ pipe with a water drip going in and a drain at the bottom. The overflow hole is 13″ above the bottom.”
So, what is the trade-off? If you are handy, somewhat experienced with electronic components, and willing to spend some hours, you can set this up yourself. Frank can help a few of his neighbors, but he has his family and ranch requiring his time, too. Otherwise, it is going to cost a couple hundred dollars or so for someone to set this up for you. It needs to be checked, maintained, and adjusted more often than the integrated water level loggers, too, so the maintenance and downloading cost can be $50 to $100 per year if everything is working well.
SECOND, theOnset Hobo U20L-04 Water Level Loggeris $300 before shipping and tax. The DWR Groundwater folks I worked with for years, use these in groundwater wells. They are easy to set up – program one and place it in a stilling well. Take it out once or twice a year to download the data. The battery life is 5 years, maybe more.
Why aren’t these automatically the cheapest option?They may be the cheapest if a diverter has 3 diversions or more, or several neighbors are using the same Hobo U20L-04.However, they are not vented, meaning that as atmospheric pressure changes due to low pressure areas and storms, the device’s pressure reading will not be as accurate. Therefore Onset recommends having a second U20L-04 set up outside the water to measure the pressure change over time. The second device can be some miles away, so one outside calibration device could be used for several in the water within a 300-square-mile area.
What I heard from colleagues is that these did not last for 10 years, and sometimes not for five years, although the device is being improved over time. Durability and reliability of a device are important for uninterrupted data, and therefore compliance with the Water Board’s regulations. The more often a device has to be replaced, the more it costs over time.
In summary, the cost of Onset Hobo U20L-04 devices is $600 plus tax and shipping. This cost may be reduced somewhat if the cost of a calibration device can be shared between several diverters, or several diversions.
THE THIRD device discussed here is theGlobal Water WL-16. This is an integrated, vented device, designed to program and set in a pipe. Watermasters have used these for years at various diversions. They cost about $1,000, before tax and shipping.
The WL-16 has a stainless steel casing and is fairly tough. They should last a good 5 years. The problem is at the sensor end – it is relatively easy to clog up in warm-water conditions, with algae and/or silt. In cool flowing water, it might operate for the whole irrigation season. In warmer or still water, it will have to be checked and sprayed clean every 1 to 3 months. Watermasters have put the sensor ends in distilled water in baby-bottle bags, and rubber-banded the tops of the bags closed to keep the sensors clean for the entire irrigation season.
One other concern which I have not discussed with the manufacturer – the manual for the WL-16 was updated in 2009 and refers to Windows XP, not the current Windows 10. I am sure that a newer manual is sent out with the device when it is purchased. Overall, with some care to check the sensor end and clean it as necessary, this is a great drop-it-in-and-turn-it-on option.
THE FOURTH device, the In-Situ Troll, has the advantage of out-of-the-box options for telemetry. The Groundwater folks at the Department of Water Resources have used these and a couple recommend these for the right application. The In-Situ
The Troll 200 Data Logger ($595) can run independently without telemetry, or be attached to the Tube 300R Telemetry System ($1,320). The Troll 200 is non-vented, so like the Onset Hobo data loggers mentioned above, an extra unit is needed for air pressure to correct the water level (pressure) recorded by the unit in the water. The cable and software for the Troll 200 are about $375.
The total unit cost for 2 Troll 200s, a Tube 300R, and accessories, is about $2,900. Tax, shipping, and installation willadd $600 and up, depending on location, elevation, and the length of the dirt road going in; and difficulty at the site and vandalism potential will add costs, too. $3,500 + for telemetered water level logging is not cheap, but it is a lot less than a full-on gaging station with satellite radio, which costs $12,000 and up for components, and over $2,000 to install in easy locations. Telemetry is expensive, there is no way of getting around that fact.
The Tube 300R requires a separate phone number for each water level logger, and cell service. In-Situ offers the option of $35/month web hosting, on its HydroVu Cloud Data Services Plan. This cost is in addition to the Tube 300R, cell phone service, and installation.
THE FIFTH and final water level logger discussed here is thePMC Versaline VL2111 – WLS-31Water Level Datalogger (replaced by the same-priced, updated model: PMC Versaline VL4511 – WLS-31). This looks much like the WL-16, but instead of a silicon bladder at the end of sensor, it has a non-fouling ceramic sensor.At $1,370 before tax and shipping, it has the highest purchase cost of the 4 listed in this post, but it is my recommendation for durability, reliability, and low maintenance.
The Versaline is made for wastewater; in other words, for sewer lines. The datalogger end is vented and it is not supposed to be submerged, same as the Vegetronix components and the WL-16. However, it is made to put inside manholes where it is very warm and humid. The PMC guys have maintained the sensor end in rough environments with the equipment lasting 8 to 12 years. If the sensor gets completely covered with algae (or something worse), it still works. It can be cleaned off with a toothbrush if it seems so clogged it might prevent water from getting to the ceramic end. The data logger and sensor are fairly new but are improvements on the older, long-lived versions.
The VL2111 – WLS-31is three times the cost of the least-expensive option. However, it might be the least expensive in the long run…it sure is the most worry-free of all the options listed here!
The PMC guys had to make a change in the sensor, so now the recommended setup is the PMC Versaline VL4511 – WLS-31 Water Level Datalogger. It will cost the same and be as durable. Regarding the reason for the change, Bob Foster at PMC wrote: “This system will come with our VL4511 level sensor and not the VL2000 that we initially spoke to you about.
The reason for the change is the VL2000 required slightly more power than what is available through the datalogger battery, so we decided to provide an upgraded sensor model, which uses much less power.
This upgraded sensor, our VL4511 also has the advantage of using:
An all-welded Titanium housing, which has a 5-year corrosion warranty
Significantly smaller diameter
Additionally, it still has anti-clog features near the sensing element to ensure reliability.”
There are many, many choices for logging water levels. These are the ones I would install, either because I, my colleagues at DWR, or larger farms or ranches have used them; or because I have checked with other users. One of these choices can serve you well!
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:
logger? PMC, Onset Computer, In-Situ, , and other manufacturers sell data loggers and water level loggers, not pressure loggers, so why is this post talking about measuring pressures at all?
3′ or longer gages are bolted to the pipe, using a survey level to make sure the 5-foot mark, for example, at the top of one gage matches the 5′ mark at the bottom of the next-higher gage. This can cost a few hundred or a few thousand dollars, depending on how much work you do vs. hiring work out, access, depth of the reservoir, and so on. 
f the reservoir using a boat. Data is dow
in whatever length of PVC pipe is needed to get from the dam at a point above where any water gets, down to the logger end. Then, no boat is needed to download data. Whic
he ditch. So, why use weirs instead of a flume, which can pass much more flow per foot of width? Weirs are better understood in this area, the ditch has adequate width, and it makes splitting the flows easier.
Vegetronix sensor. The box is a little bigger than needed, but seems to work. I’m trying to get the data to download into something I can analyze, but it seems to work very stable.
was updated in 2009 and refers to Windows XP, not the current Windows 10. I am sure that a newer manual is sent out with the device when it is purchased. Overall, with some care to check the sensor end and clean it as necessary, this is a great drop-it-in-and-turn-it-on option. The cost for a WL-16 is $1,000; with with tax, shipping, and cable, about $1,450 per diversion.
iameter, but I think the cost range for 4″ to 12″ pipes is around $1,400 to $3,000, before tax, shipping, and installation costs. That’s a reasonable price for a quick-to-install device that measure up to about 5 cfs in a 12″ pipe. 
Bob Foster at PMC wrote: “This system will come with our VL4511 level sensor and not the VL2000 that we initially spoke to you about.