Installing Reservoir Staff Gages

How is a staff gage installed in a reservoir?  The typical way is to drive a piece of 2″ galvanized pipe into the ground, deep enough to so it isn’t easy to push over.  If cattle will be in the reservoir to get water, then the pipe needs to be really well installed.  A gas-powered post pounder can be rented at Rental Guys, Home Depot, or similar places.

Most reservoirs are deeper than six feet, so it’s best to maximize the length of pipe installed.  The length of pipe that can be installed by hand is usually about 6 feet.  For a 6-foot tall pipe, about 3 feet of pipe needs to be in the ground, so the total pipe length is 9 feet.

Then the staff gage is attached to a 2″ x 8″, using screws or small bolts.  Staff gages vary in width from 1″ to 4″; the usual USGS Style C staff gages are 2-1/2″ wide.  Once the staff gage is screwed on, the board is U-bolted to the pipe.

That’s it…except for the surveying part.  The top of staff gage needs to be at the same level as the spillway crest, so the maximum water surface elevation can be measured.

If the reservoir is deeper than 6 feet, and most are, then staged staff gages may be needed.  The first gage is installed at the top, going from, say, 6 feet to 12 feet.  The second, lower staff gage is installed from 0 feet to 6 feet, and 6 feet is exactly the same elevation on both staff gages.  In the photo below, there are 3 staged staff gages to measure 18 feet in elevation.  The top of the third, lowest staff gage can be seen in the bottom right corner.

What if a pond is full, or mostly full?  It is still possible to install a staff gage, but it will be harder.  Boats or rafts will be needed, and the pipe with the board already attached has to be put in place and held vertical while being driven.  If the total depth is greater than 6 feet, then a longer pipe, board, and staff gage will be needed, and the combined weight will be that much greater.  Hint: tie a rope and buoy to the pipe so when if it slips and sinks, it can be pulled up again.

What about installing a staff gage along the slope of a dam, to avoid having to wrestle a pipe and board for a deep installation?  This can be done by attaching a length of rebar or pipe to the dam face using concrete stakes or similar method.  The slope distances measured are converted to vertical depths.  However, this won’t stand up well to cattle or elk traffic, and it is more liable to be vandalized if the reservoir has easy access.

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Option For Pipe Flow – Seametrics Paddlewheel Meters

How do you measure flow in a pipeline?  The simplest

McCrometer Magnetic Meter

way is integrated, saddle-mounted propeller or magnetic meters.  For example, see the post on McCrometer magnetic flow meters:  https://allwaterrights.com/tag/inline-magnetic-flow-meter/.  Propeller meters look much the same.  Both mount through a hole cut in the pipeline, making them quick to install, and easy to remove for maintenance.  These meters can handle some sediment and still be accurate, although water with a lot of silt and sand wears out propellers faster. 

McCrometer Propeller Meter
Installing Propeller Meter

 

 

What about cost?  For integrated meters, the costs start at about $3,200 delivered, and go up with diameter.

If you want to spend the least amount of money and still have accurate flow

DL76W Wall-Mount Data Collector

measurement, a paddlewheel meter may be a good solution.  These can be integrated, or can be assembled from the meter, data collector,

IP800 Paddlewheel Meter

display, and possibly other parts.

 

For an idea of the cost, an IP 800 paddlewheel meter, FT450 display, and DL76 data collector for a small pipeline cost about $2,000 delivered. 

FT450 Data Display

That is about $1,200 cheaper than a magnetic meter for the same-sized pipeline.

 

So, why not always use a paddlewheel meter rather than more expensive magnetic or propeller meters?  Paddlewheels wear out faster if there is sediment in the pipeline.  I have seen installations where pumping from a muddy river wore out a paddlewheel

Saddle for Paddlewheel Meter

in a year, but a propeller meter lasted 3 years pumping from the same river before needing refurbishment.  The shaft and wheel can be replaced in the field, at a lower cost than propeller or magnetic meter refurbishment.  However, busy farmers and ranchers don’t have time to check the paddlewheel once or twice a year, so the meter installation is at a greater risk of losing data than a propeller or magnetic meter.

Paddlewheel Meter in Saddle

If you are brave or experienced enough, you could get a paddlewheel integrated with the data collector, and no external display.  This would get your delivered cost down to about $1,500.  Data needs to be downloaded more often, perhaps every 2 to 3 months, to ensure the meter is working correctly.  Also, the meter needs to be installed from the side, not the top, so more clearance is required to the side.

DL76 Data Collector Mounted on Paddlewheel Meter

Measure Any Flow With Watchman Flumes

How can large diversions be measured?  Long-throated flumes are a good option, especially if the ditch has low banks, or a lot of sediment or debris could clog a weir or orifice.  Premanufactured Parshall or Replogle flumes go up to around 20 cubic feet per second (9,000 gallons per minute).  If they are made for larger flows than that, they are prohibitively expensive to ship or manufacture.

Watchman 10 cfs flume

Recently, though, Watchman long-throated flumes have become available.  They are made in Northern California, so shipping costs are lower.  They typically go up to 20 cubic feet per second in size, but I have installed a 30-cfs Watchman flume.  The manufacturer can easily make larger-capacity flumes, too – standard plans go up to 60 cfs, and they can be shipped in ready-to-assemble sections for up to 200 cfs.

Watchman flumes are made of 10-gauge steel, a little thicker than 1/8 inch.  The premanufactured flumes I have seen ship from outside the state are made of 16-gauge steel, which is about 1/16″ thick.  These can work well if care is taken during installation, but the Watchman’s heavier gauge steel can withstand more backfill and rougher treatment.  They’ll last longer, too.

Watchman 20 cfs flume

What about cost?  It turns out that Watchman flumes are about the same cost per cubic foot per second, as flumes made from lighter-gauge steel.  Some farmers and ranchers like concrete better than steel.  Watchman flumes can be built inside Briggs pre-cast concrete rice boxes and weir boxes, if you need an installation to last for 30 years or more.

Where can you buy these?  The manufacturer does not advertise – let me know and I can put you in touch with them.

Bluetooth Hobo Logger Saves Money and Time

Onset has a neat Bluetooth Hobo water level logger.  The MX-2001, with the cap removed, hooks up to the MX-2001-TOP with a cable, and once installed, is

downloaded with the free Hobomobile smartphone app.  The app does everything you’d normally need a data shuttle and cable for – starting, setup, configuration, downloading, and stopping the logger.

 

 

The top unit with the Bluetooth radio has to be out of the water, so of course the top of the stilling well holding the unit has to be 1.0 feet or higher up out of the water.  If the stilling well is galvanized iron pipe, you’ll need to get within a few feet to download it.  If you are using PVC you might get a connection at 100 feet.

Will two units close to each other interfere?  Nope, the app finds both and lets the user choose which unit to work with.  As with any water level logger installation, keep a logbook or spreadsheet with the Serial Numbers for each location so you aren’t confused later.

What about barometric pressure?  The TOP unit records barometric pressure, so you don’t need a second unit for atmospheric pressure, nor do you have to know the elevation difference between two separated units.  The unit subtracts atmospheric from absolute pressure, then gives you all 3 values when you download:  absolute, atmospheric, water only.  That makes data processing much easier.

In California, you should be able to get one of these shipped to you for $750.  Compare that to the regular Hobos, which need one in the air, one in the water, and a data shuttle and cable.  It would put you back almost $1,000 to get the separate pieces shipped to you.  If you have two or more locations to log, then the old style is less expensive as far as parts go.  Still, the Bluetooth version is likely more cost effective when you consider the minutes saved each time the Bluetooth unit is downloaded, compared to unlocking or unscrewing the cap, getting the water unit out, downloading it, and replacing the cap or lock.

Upcoming AB 589 Self-Certification Courses, end of June through August!

I promised to post more information on AB 589 Self-Certification course dates…and then I did not find out where the web page with the list of dates is.    Thanks to Jenn Koch from the U.C.’s Woodland office, we have some course dates.  By the way, I took the course, and it is very well done by Dr. Khaled Bali, Larry Forero and Allan Fulton from the UC Cooperative Extension:

  1. June 29 (AM Training) UCCE- Humboldt County-(Eureka)

  2. June 29 (PM Training) UCCE- Trinity County-(Hayfork)

  3. July 9    UCCE- Modoc County (Cedarville)

  4. July 10  UCCE- Siskiyou County (Yreka)

  5. July 11  UCCE- Yolo County (Davis) – NOTE, location on AB 589 web page is incorrect

  6. August 29 UCCE- Plumas/Sierra Counties (Taylorsville)

  7. August 30 UCCE- Glenn County (Elk Creek)

How To Survey A Reservoir

Pond In Mountains, Photo Credit: Pixabay
Pond In Mountains,  Credit: Pixabay

If you have a reservoir, the Water Board requires you to measure and report: how much you divert to it, how much water you store in it by month, and how much water you release if the pond has a controllable outlet.  It is usually not possible (or at least not feasible) to measure the inflow, so what is actually reported is the monthly positive change in storage, the amount that fills it up.

If your reservoir is less than 10 acre-feet (AF) per year, you only have to report it.  Measurement is not required.

How do you know how much is stored in your reservoir?  Each pond needs an elevation-storage table or curve, as the Water Board calls it.  Engineers call it an area-capacity table or curve – that’s what I created during part of my career as a water bureaucrat.  I’ll use the Water Board’s terminology here since water diversions and storage are reported to them.

First check to see if the Water Board or Division of Safety of Dams has an inspection report for your reservoir.  If not that, then an elevation-storage table or curve may be available.  You can have it emailed as a PDF.  If there is no information for your reservoir, then you have to create the table and curve yourself.

First a reservoir has to be surveyed, so you know how full it is for any given elevation of water.  The elevations start at zero storage.  The figure below shows a cross section and the contour map for a reservoir with a minimum elevation of 86 feet.

Pond Contours. Photo Credit: civilblog.org
          Pond Contours,  Credit: civilblog.org

How do you survey a reservoir?  You could hire an engineer or surveyor to survey it.  Depending on your budget and your need for accuracy, the elevation-storage table from a survey could be anywhere from +/- 5%, to +/- 10% accurate.  The Water Board requires +/- 10% for larger reservoirs, and +/- 15% for 100 acre-foot (AF) or smaller reservoirs.  I recommend aiming for +/- 5% in case you have significant errors elsewhere in the measurement system.

On the high end, the survey could be done using GPS survey instruments, so the result could be accurate and could overlay other digital maps.  Almost as high a cost is to have a transit with EDM (electronic distance measurement).  Robotic units only require one person acting as the rodman, and the instrument “follows” by keeping pointed at the laser prism reflector.

At the bottom end of the scale, a survey level or possibly a hand level, and a couple of 100′, 200′, or 300′ tapes can be used.  Many survey levels can read horizontal angles within a degree or two, so the instrument person can note angle and distance to every point.  If angles are not used, then two tapes are used, one to measure the distance along a side, the other to measure perpendiculars out to the rodman.  In the boat, the rodman measures depths, and on land he has a telescoping level rod to get elevations above the Photo_0188water level.  This way you measure X and Y distances that are plotted on a grid along with each point’s elevation or depth.

With plotted points, now you can draw contours for every foot, or every two feet, or every five feet, depending on the size of your reservoir.  Then calculate the area for each contour, and the volume between each set of contours.

Here’s where Google Earth can be your best friend.  Navigate to your property and reservoir in Google Earth.  Then take a digital photo of your contour map, and import it into Google Earth as an image overlay.  Make it 50 percent transparent, and move and resize the image until it fits over your reservoir.  Now you can use the polygon tool, trace over your contours, and let Google Earth calculate the areas for you!  Make sure to get those areas in square feet or acres and not square miles.

An alternative way of doing this is to print out a map of your reservoir from Google Earth, then draw your survey points and contours right on that map.  Then when you import the scanned or photographed, edited map, it will be a lot easier to overlay on your reservoir.

Make an elevation-storage table and draw an elevation-storage curve like the one below.

Let’s look at an example.  To get the reservoir volume, add the areas of two adjacent contours, say, the 90-foot contour and the 92-foot contour, divide by 2, then multiply by the elevation difference (in this case, 2 feet).  If the 90-foot contour has an area of 6.1 acres, and the 92-foot contour has an area of 7.6 acres, the calculation is [(6.1 + 7.6)  / 2] * 2 = 13.7 AF.

190-AF Reservoir Capacity Chart

Here’s the great thing about simple methods: anyone can measure his own reservoir by reading up on it first (Google, Bing, or DuckDuckGo) and then taking some care (and good notes) to do the job well.  If the topography is difficult, or the pond is too large for tapes, or you are just too busy doing the work you have to get done, then talk with an engineer and negotiate cost vs. quality and accuracy.

Great AB 589 Self-Certification Training!

I attended the Flow Measurement Devices and Methods course in Cottonwood yesterday, for diverters to become a “qualified individual” per AB 589.  What a great class!  All my appreciation and applause to Larry Forero, Allan Fulton, and Khaled Bali of the UC Division of Agriculture and Natural Resources, who taught the course.  They laid out the requirements and the details of several ways to comply with SB 88, including weirs, flumes, water level loggers (pressure transducers with data collectors), in-line meters, in-line differential pressure, how to determine and track reservoir volume, and how to report changes in volume.

There were specific examples of how to size a weir to install the correct device, how to convert measured flow rates to the volumes that must be reported to the Water Board, and how to select an inline meter if your diversion is piped.  There were detailed examples of how to comply with the Water Board’s reporting requirements, and discussion of the most relevant parts of SB 88.

I hope that Larry and Allan will make their Powerpoint presentation available online for public use.  It is well done and really helps understand how to comply with SB 88, both in the field and online at the Water Board.

Update:  Allan Fulton contacted me and let me know that this course IS accepted by the Water Board!  So sign up, take the 3-4 hour course, and you will be certified to install your own measurement device(s).

I heard a week ago that it isn’t a 100 percent lock that completion of the course will be accepted by the Water Board.  However, the course is more than adequate in my estimation, and I don’t think the Water Board has any alternatives to comply with AB 589.  It is going to be accepted!

AB 589 says, in part:

“…any diverter who has completed an instructional course regarding the devices or measurement method included in the course administered by the University of California Cooperative Extension, including passage of a proficiency test before the completion of the course, shall be considered a qualified individual when installing and maintaining devices or implementing methods of measurement that were taught in the course for the diverter’s diversion.”

Thanks to the Shasta Livestock Auction Yard for providing the location – my guess is that there were 140 people attending, a good crowd for this narrow subject.  The Cattlemen’s Association got the word out and provided refreshments.  It was hundreds of hours of work among 8 people or so to pull this off.  Job well done, everyone!