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.
If you have a pipeline as part of your diversion, then an in-line meter with an integrated data collector can be installed. The data files from these units are
easily readable in Excel, and the files can be sent directly to the Water Board to meet the requirements of SB 88.
What if you don’t have a pipeline? Then your flow needs to be measured in the open ditch with a weir, flume, or orifice. These devices measure the flow but they don’t record the data. To continuously record data, a submersible logging instrument must be used to measure the water pressure at the bottom of the box. These logging instruments are commonly put into stilling wells that are inside or outside the measurement device.
How are water pressure logger measurements converted to diverted flows or reservoir storage? Why does anyone even have to have an electronic pressure logger? Onset Computer, PMC, 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?
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 1.60 psi, then the calculation to get depth is 1.60 psi / 0.4335 psi per foot = 3.69 feet of depth.
Note that water level loggers can be of two types. The least expensive are completely submersible, and do not compensate for barometric pressure. For an idea of the readings of barometric pressure in a measurement device, a 2 foot deep logger records a pressure of 0.8670 psi. Atmospheric pressure at sea level is about 14.7 psi, and high in the mountains may be 12.0 psi. Air pressure is much greater than those measured in ditches. Usually two of these loggers are used at once, one in the water, and one out of the water measuring only air pressure. This also eliminates the variability in pressure due to weather changes.
The second type of data logger compensates for barometric pressure at the same time water pressure is being recorded. That way, the water and air pressure data sets do not have to be combined before conversion to depths. These loggers were always more expensive until the Bluetooth Hobo water level logger came along; as of February 2019 I found that it is the least expensive option for a single location.
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.
For diversion ditches from a stream, 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:
Back in 2005, Arnold and Eileen Williamson bought property near South Cow Creek in Shasta County. They live in San Bernardino and plan to retire early, and build a new house on their land. The parcel is part of an old ranch just off Highway 44.
The Williamsons paid $220,000 for the 3.55 acre lot. That seemed high compared to similar parcels in the area, but they were assured the land has adjudicated water rights from South Cow Creek.
Arnold and Eileen brought their travel trailer to live on the land while they are building a new house. Their savings account is in good shape so they are going to build a nice 2,200 square foot, single story ranch house with a garage and a shop. They talked to a well driller 10 years ago and he assured them it would be easy to put in a well, for a cost of around $18,000.
When Arnold and Eileen went to get a permit to drilla well, they ran into unexpected problems. Parcels on either side have their septic systems close to the common property lines, so their possible well locations are few. Maybe a bigger issue is the passage of the Sustainable Groundwater Management Act in 2014. Will their pumping rate be limited, and will their well-drilling permit application get held up?
Now the Williamsons are checking into their surface water right. Is it enough for some pasture for horses and a few cows, in addition to the house and garden? The Turings who live on the east side say there are no water rights. The Poulans, to the west, say they have lived here for 6 years and they have never had water – they think the water right was bought off the place, or lost because of non-use. Now the Williamsons are upset and headed toward just plain mad. The real estate agent said they had rights, and didn’t the title companies insure it?? After a few frantic calls, they found out that title companies don’t insure water rights. But, their realtor gave them the number of some folks over on the north side of the highway, and they have a “decree map”. Arnold and Eileen head over to the Winters’ place to look over the maps. Brad and Jenny Winters even have a web address where the decree and maps can be downloaded: https://allwaterrights.com/some-decrees-maps/ The Water Board’s web page has the decree, but no maps: http://www.waterboards.ca.gov/waterrights/board_decisions/adopted_orders/judgments/docs/cowcreek_jd.pdf.
It turns out that the Cow Creek adjudication does not have maps, but an engineering report done a few years before the decree was issued does have the maps. Brad and Jenny have that report, too, so they have Sheets 1 through 5 showing the “Diversions And Irrigated Lands” on Cow Creek. Besides that, they have the link to where they can get the South Cow Creek decree, and a link to a blog that has the maps not on the Water Board’s web site: https://allwaterrights.com/some-decrees-maps/ Sheet 5 covers the area including the Winters and Williamsonplaces. Sheet 5 has a lot of “irrigated lands”according to the legend – the green areas.
By looking at the maps, and their Assessor Parcel Map they have in their escrow package, it sure looks like their property is completely within the green area. Great! Now, how do they figure out if they actually have a water right?
Arnold and Eileen wonder, can they figure this out themselves? Brad and Jenny tell them, they sure can, and there is a document online that explains how to do it: https://drive.google.com/file/d/0B8G8oUBnppMTdU1lbUotUDR4MlU/view. They take a look at it and see that, yes, the document fully explains the process, but it requires having either AutoCAD or GIS software. Also, it will take deep familiarity with the decree – and it is starting to look like a 3-day job just to understand it enough for their parcel! Arnold and Eileen don’t have the software or experience, so they decide it’s not worth their time to learn this…and they are not sure if they can do it right.
After asking around, Arnold and Eileen figure out they will need to see anattorney. They call around and find out there are a couple of engineering companies that can see them faster, and they might cost less. They picked Rights To Water Engineering, Inc., to help figure out their water rights. Within a couple of weeks, they have a nice report in their hands and answers to their questions. So what did they find out? The map below is one of several from the report they got from the engineer, showing their property boundary on the 1965 decree map of irrigated lands:
The report cost $2,500. The engineer warns them that if it gets contentious and they can’t work out access to the water with their neighbors, they may end up having to get legal help. He recommends a couple of local water rights attorneys if it comes to that – there are some good lawyers who specialize in in water rights. For now, though, they have documentation they can discuss with their neighbors to work on getting their water right to their property.
Their property is on land that back in 1968 belonged to Howard and Gladys Leggett. It has an adjudicated second priority water right for irrigation equal to 0.063 cubic feet per second, or 28.5 gallons per minute, 24 hours a day, 7 days a week, from March through October. This 2nd priority right is less than the second and third priorities on the upper creek and tributaries, but it is the highest irrigation priority on the lower creek. Back when the property was flooded, that was usually enough to flood irrigate their entire lot to grow pasture or hay.That’s great news!
As natural flows drop during the summer that amount is reduced and everyone with a lower creek second priority has to reduce their diversion by the same percentage. In normal and wet years they could keep their pasture, hay, or whatever else they plant, irrigated for most or all of the irrigation season. And whether or not they use the water, the right does stay with the land and protect their property value; there is no provision for the expiration of water rights in the decree (the same as for nearly all surface water rights decrees).
What else was in their report? There was a cover letter, and next some excerpts from the decree. Schedule 1 lists the places of use for all the original owners. The Leggetts’ description takes up most of page 60; the Williamson’s property is on the 69.8 acres listed in the second paragraph for the Leggett land:
Schedule 2 lists all the points of diversion, whether gravity diversions or pumps. The Leggett property actually could get water from two diversions, a pump from the creek, and a proposed second, movable diversion on the creek. That’s convenient – per the decree they could already divert their water from someone else’s existing diversion, or pump their water from Diversion 95, or they could get it from anywhere they can get agreement from the landowner!
Schedule 6 lists the water rights for Lower Cow Creek – other schedules have rights for the upper creek and tributaries. This is interesting: there are four priorities of rights and this part of the Leggetts’ property has
a 1st and a 2nd priority right. What does that mean exactly? The decree explains that 1st priority rights are domestic – houses and gardens. It’s a very small right and it is not clear whether or how it should be divided up among the all the subdivided parcels that used to be the Leggett ranch. The engineer noted it in the cover letter.
How was the water right calculated for the Williamsons? Using a geographic information system, or GIS, the engineer used his training and years of experience to precisely overlay the Assessor Parcel Map on the decree map. Then he measured the acreage for both, and prorated the water right by area. The following screenshots of the Excel spreadsheet shows these calculations.
Time to fess up: this was a water right subdivision of a fictitious, made-up parcel of land, and the Williamsons don’t actually own it. However, this story is one that happens every day, when a landowner asks “How much is my water right, really? Can I divert for hay, stock, pasture, wildlife habitat, crops not mentioned in the decree, an orchard, ……… ?” Having information before arguing with neighbors, seeing attorneys, sending legal letters, and going to court, can help smart people who generally have good relationships work out happy and agreeable solutions. The Williamsons were smart and talked politely with their neighbors, the Turings and Poulens and Winters’s. Now they have a good basis to live peacefully in their neighborhood for many years, and Arnold can borrow Charlie’s lawnmower until he gets his own.
Market part of your water, as a lease or sale, or divert it all and don’t risk losing your water right? That’s the question for thousands of Sacramento Basin smaller districts and individual diverters of even large water rights. The market for water can bring the water right holder $25 – $1,000 per acre-foot, depending on whether the buyer is a nearby neighbor or a San Joaquin Valley water district in a dry year.
When I was a DWR bureaucrat, my supervisor was experienced and wise. When he would talk to people at public meetings, or to neighbors who knew he was in the water world, sooner or later the subject of “sending all our water to Southern California” came up. His reply was, “You’re right, Feather River water is going to L.A., Sacramento River water is going to the San Joaquin Valley, and the excess of both goes through the Delta out to the Pacific Ocean. And you know what? Gravity does the job, not the government. If you want to keep water in Northern California, there have to be more dams.” Some folks understood and changed their minds, others kept on complaining.
There are more reservoirs in the Sacramento Basin. They aren’t made of concrete, they don’t do flood control, and they’re not run by the state or federal governments. These reservoirs are the water evaporated, infiltrated, leaked, returned unused to the stream, or wasted at the diversions of many individuals, and some water and irrigation districts. Some of the excess water makes it back to streams, and some of it goes to the next diverter down the stream, but much is lost in the short term and unavailable for use by humans or the environment.
Yes, many surface water flood systems were designed this way, so runoff from one irrigator goes into the canal to the next. However, more flooded pastures are being leveled or converted to pivots to grow hay. Many other pastures are becoming orchards, with tight controls on incoming e coli from cattle or unwanted pesticides or herbicides. There is a huge opportunity to increase efficiency (pipe, sprinklers, etc), maintain better water quality.
How can anyone get a yield, or excess water out of those reservoirs? Lining ditches, converting to sprinkler instead of flood irrigation, changing the land use to a crop that has both higher value to the owner, and lower water use.
I’m not saying that’s a bad thing that this excess water exists. In fact, it has the potential to do a lot of good, both for the upstream district, and for fisheries, and for other environmental needs, and for water users downstream or south of the Delta who don’t have enough water.
What is the good for the district or individual who is selling or leasing the water? Well, there is water not being directly used by stock, or being applied to crops, or directly needed for groundwater recharge. If some of that water can be saved, it can remain in the stream and used for all the other needs. Agricultural, urban, and environmental water users will pay for the saved water. That water can also bring in a lot of cash, that can be used for further farm or ranch efficiency, general improvements, or cash to keep in the bank.
Why don’t more irrigators with excess water market it? The number one reason is fear that somehow, California or the Feds will eventually take away the water right. That is a concern, but there are a bunch of people selling water right now who will tell you that their water right is still rock solid. The second reason is that we have always irrigated this way, so why should we change? Both the fear of loss and the unwillingness to change can be overcome with just a little bit of self-education. Plenty of folks have overcome their lack of knowledge to put together some valuable water deals.
Lately, the Sustainable Groundwater Management Act, SGMA, is throwing in a lot of uncertainty. It’s true that radically changing diversion practices might change groundwater recharge, so that pumped water is not fully replenished. So, put together a small deal and see how that goes. Call it a trial for one or a few years. That will provide data on what the groundwater changes were due to the water deal.
What about those folks in the San Joaquin Valley who really need the water, badly? There is an element of taking care of our neighbor, and it ought to be part of the consideration. Who is our neighbor? Anyone that we can or do benefit.
You have to measure your surface water diversion, or elevation changes and outflows from your reservoir. Data processing, checking, correction, and summarizing requires a Data-Head who has experience dealing with this kind of data.
SB 88 requires diverters to measure diverted water flow and/or volume, then report the measurements. For small to medium-sized diversions and reservoirs, there is a often transducer measuring and recording pressure. The pressure data has to be converted to depth and flow, or depth and volume. Data may be hourly, daily, weekly, or monthly. Whatever the frequency, the Water Board wants data files uploaded with annual Reports and Supplemental Statements.
Where’s the manual for how to do this, for any of several data loggers, and for meters, weirs, flumes, and orifices, and flumes? It exists in pieces and parts. Each data logger manufacturer has a manual for each product. Sometimes products are similar, and sometimes very different, as are the manuals. The long-existing measuring devices, weirs, flumes, and orifices, are described and general measurement instructions listed in the U.S. Bureau of Reclamation Water Measurement Manual.
When it comes right down to it, a person has to be a “data-head” to enjoy collecting the data, and going through all of it to find bad results, missing data, and odd trends. Then stage and flow have to be calculated and checked against periodic readings taken during visits to the reservoir or stream. Data have to be listed in a format to upload with the Report or Supplemental Statement to the Water Board, and summed monthly to fill out the online form.
If you enjoy educating yourself and taking on new tasks, then you can be a data-head. If not, then you’ll need to have an employee do it, or more likely hire an expert.
Who are the experts? There are engineering firms, manufacturers, vendors and others who can download data for you. It still comes down to the person helping you That person who does the work has to have done data reduction, calculations, checking, and quality control in the past.
Make sure you get help from someone who knows data inside and out! If the Water Board has any questions, your data-head can explain and defend every bit of it for you. He or she will already know the answers to any questions that come up.