How Do You Record Diversions? Water Level Loggers, Value Vs. Costs

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.

  1. 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)
  2. 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….)
  3. Global Water WL-16  ($1,000; with with tax, shipping, and cable, about $1,450 per diversion)
  4. In-Situ Rugged Troll 200 Data Logger and 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)
  5. 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 is the 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)
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:

Shawn_Sticking_WeirFor 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.

About_1.4_cfs_over_weir_edited_smallWe 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 retiraqua-plumbed 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 the Vegetronix Aqua-Plumb Water Level Sensor connected with the Logger-8-USB.  Together these are $340, which is
the least cost of anything that I have seen.   With this you will have all thelogger-8-usb
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_frank_1_p1300077vegetronix_frank_2_p1300078Vegetronix 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, the Onset Hobo U20L-04 Water Level Logger is $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 dowonset_hobo_u20l-04-editednload 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 onset_u20l-xx_handhelda 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 the Global 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.global_water_wl16-edited

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-16globalwater_wl16_in_field 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

in-situ_rugged_troll_200_loggerRugged Troll 200 Data Logger and Tube 300 Telemetry System.

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 2 Troll 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 the Tube 300R telemetry 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 in-situ_tube_300r_telemetrylevel 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 the PMC Versaline VL4511 – WLS-31 Water 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-31 is 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.pmc_header-editedversaline-vl4511-and-wls-31-water-level-datalogger-specs-editedThere 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!



How Do Shared Ditch Users Comply With SB 88?

This is a summary of how water right holders who share a ditch comply with SB 88, and report correctly to the Water Board.  So, why I am I using the Measurement Method Form Instructions below?  Because, this has the best summary that I have seen, of how a shared ditch is measured and reported.  In short:

  • every water right holder on a ditch has to sign onto the same form;
  • each person’s split, land use, and irrigated acreage must be reported;
  • the ditch manager and each person is responsible to report leaving the agreement – presumably this covers every property sale, too.

Excerpts from the Instructions:

…Examples of Measurement Methods include:  Multiple water right holders on a single surface supply may propose a collaborative measurement approach.

“…Attach maps, aerial photographs, or other renderings showing the area covered by the Method and delineating the acreage of each place of use served. For the area covered by the Method, include a list of assessor’s parcel numbers and the current owner of each parcel. Attachments can be uploaded in Section H of the online form.

…A Measurement Method based on using a shared measuring device shall include the following information:

  • Description of the methodology used to apportion the volume of water delivered to each diverter covered by the Measurement Method.
  • Description of the field or flow condition at each diverter’s delivery point, including duration of or period of water delivery, annual water use patterns, irrigated acreage, crops planted, and on-farm irrigation system.
  • Description of the consumptive use of water for each individual diverter, if available….”

“…A Measurement Method based on using a shared measuring device shall be accompanied by a written agreement signed by each diverter covered by the Measurement Method.

“…Each participant in a Measurement Method plan must sign the form or an “opt-in” form which must be retained by the Measurement Method manager. (Attach an excel spreadsheet listing of participants, as needed). Each Measurement Method participant shall acknowledge that the method will substantially comply with the measurement and monitoring requirements.

“…Each Measurement Method participant is responsible for promptly informing the Division of Water Rights or the Delta Watermaster, as appropriate, if the participant withdraws from the Method. The Method manager is responsible for promptly informing the Division of Water Rights or the Delta Watermaster, as appropriate, if the Method is modified or abandoned….





How To Get Water Board Forms: ADD’L TIME, Meas. Method, Alter. Compliance

Many diverters have filled out the forms due April 1, 2017 – a few days from now.  For those who have not, how can you get to the Water Board Forms you need now?  See below.  Note: for any of the 3 forms, you can still update information after you click the SUBMIT button.

UPDATE:  Revised:  For any of the 3 forms listed below, save the text from each box where you make an entry, to Word or Notepad.  If you get an error message, keep hitting the Previous and Next buttons, and/or browser forward and back buttons until text is saved, or the box blanks out and then reenter the text you saved to Notepad.  Especially when attaching files, you may have to go forward and back 10 times, and reattach files, before they’ll “stick’.  Entering “too much” text in the form fields can lock up the web page, after you have already gone on to the next, and nothing will save.  The advice is to enter less text, then add more and resubmit, and more and resubmit….

  1. REQUEST FOR ADDITIONAL TIME – fill this out if you don’t have your device in, or you have not filled out the other 2 forms.  Put in lots of detail. 
  2. Measurement Method
  3. Alternative Compliance Plan

Start at the Water Right Form and Survey Submittal Portal:


Log in with the User ID and Password you used in past years, or from the last reminder letter that the Water Board sent to you:


This brings up the Water User Dashboard:


Fill out the report(s) you need, or have your qualified individual do it.  Done!  If you do not have your password, or even your login ID; go to the Electronic Water Rights Management System (eWRIMS) Report Management System (RMS) page and get the information you are missing:

Deadlines Are Here / How Can You Comply Fast?

This is a reminder, if your diversion is over 1,000 AF per year, then these deadlines apply:
January 1, 2017 – Installation of a certified flow measurement device, or devices.
April 1, 2017:
  1. REQUEST FOR ADDITIONAL TIME FORM, if your device was not installed by January 1, 2017.  Go to and use the User ID and password that you have been using or that the Water Board gave you in a reminder letter.
  2. Measurement Method – diversions over 100 AF/year have to be certified by a qualified professional, although the deadlines for 100 to 1,000 AF  diversions are July 1/October 1.  You can build it but it has to be certified.
  3. Alternative Compliance Plan – if your device does not comply, or standard devices will not work, but you have a reasonable measurement plan, fill this out.  It will be posted online by the Water Board, and they do not approve or evaluate it.  If nobody (state or federal agency, group, or individual) complains to the Water Board, you’re done.  If the Water Board says it’s not good enough, you may have as few as 30 days to put in a compliant measurement device to avoid fines.
  4. Supplemental Statements Of Diversion And Use for Water Rights Under Applications, Permits, and Licenses.

What Device Can You Put In Quickly, if Your Diversion Is Over 1,000 AF/Year?

          A temporary weir can be put in fast – as little as half a day.  You should be able to say it’ll last a couple of years.  It needs to be sealed up with plastic and/or dirt so it does not leak through or around.
          Whatever you do, it has to be certified…but by whom?  According to, it can be:  “… A) A California-registered Professional Engineer; or B) A California-licensed contractor authorized by the State License Board for C-57 well drilling or C-61 Limited Specialty/D-21 Machinery and Pumps; or C) A person under the supervision of a California-registered Professional Engineer and employed to install, operate, and maintain water measurement and reporting devices or methods; or D) In the case of a right or a claimed right to divert by an agency of the federal government, a hydrologist or professional engineer experienced and trained in water measurement who is employed by the federal agency in that capacity….”
          The ideal weir, whether suppressed or contracted, needs 2′ available depth upstream and downstream of the weir boards.  That’s enough for an (ideally) 1.5′ high weir, plus 0.45′ static head on top of the weir boards.  The water downstream needs to be at least 0.25′, or 3″ below the top of the weir boards to have a good nappe (air gap between the boards and falling water).
          The 0.45′ static head gives 1 cfs per foot of length of weir.  You can go higher with the special Kindsvater-Carter equations – you’ll use those to develop a rating curve.  You can drop the weir boards down a little, but not so much you drown out (submerge) the weir.  So, ideal parameters can be stretched some if you take great care to use the correct calculations.

         When it comes right down to it, 2 braced T-posts, or 2 lengths of galvanized pipe, with boards and plastic could be certified as compliant for a year. 

     Temporary Weir In Ditch

 I have done that in a pinch when I was a bureaucrat Watermaster.  The important things are the heights and depths.

          One more possibility – use an orifice in your weir box, but you would have to have 2 data collectors per measurement device.  An orifice can have as little as 0.2′, or 2.4 inches of head difference between upstream and downstream; more head is better for accuracy.  If the ditch is really flat, use a weir setup that has exposed weir boards down to the sill of the device, so you can cut a hole in a lower board for your orifice.

What Does A Measurement Device Evaluation And Proposal Look Like?

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: