This blog is about California water rights, diversions, devices, and how measurement devices work, plus a few posts on larger or different issues. For a great source on a wide variety of water concerns in California, check out the California WaterBlog: https://californiawaterblog.com
Reading this is like taking some college classes (but faster and more interesting), especially if you check out some of the linked sources.
“Mornin’ Lisa, this is Will. Hey, my diversion dropped off last night. You’re the next water user upstream, so I thought I’d check if you made a change last night.”
“Hey Will, how are you folks? Yeah I did. I was only taking 50, and my right is 112, so I bumped it up to my full right.”
“112?! How’s that work? My farm is bigger than your place, and I only get 20! Well Lisa, I think you’re taking too much and you better turn it down. There’s no way you get that much!”
“Will, when we bought this place from the Sarco’s 4 years ago, they showed me in the deed where the ranch gets up to 112. It’s right there in the deed…. Do you and Roberta have a deed or something, Will? How ’bout me and Steve come over and talk about it. Joe down on the bottom told me there’s been water wars here, and I don’t want hassle if we can avoid it.”
“Sure, come on over, we may end up talking to lawyers but let’s see if we can figure it out first.”
The next morning, Steve and Lisa went over and dropped in on Will and Roberta. Lisa showed Will right in the deed where, sure enough, it said” …all water rights appurtenant to the parcel, in the amount of 112 gallons per minute…” They also showed a Permit from the Water Board, for the same amount.
Will and Roberta laid out a copy of their 1882 filing with the county, where it showed their ranch, one of the original ranches in the decree, with a water right of 20 miners inches.
“Lisa, wait a minute, you guys divert in gallons? How does that match up with miners inches?? Most everyone around here diverts in miners inches, not gallons.”
“When we bought the place, Joe Sarco showed us how our farm was subdivided from the original parcel. Will, Roberta, you guys know, his farm was split into 4 equal parcels. When he did that, and the water rights were divided up equally too. Well, the other 3 parcels got 111, and ours got 112 gallons per minute, almost equal.”
“Well, how much is gallons per minute, in miners inches. Steve, do you know?”
“I have no idea. I suppose we can figure it out. I went and look at our box, and your headgate, Will, and it looks like you are diverting several times as much as we are.”
There are all kinds of ways to measure flow and storage. Flow rates for agricultural diversions in California include gallons per minute (gpm), miners inches, inches of head, shares, heads, and acre-feet per day (AF/day). Take a look at the following table from http://www.jennessent.com/unit_conv/manual/no_frame/flow1.htm – there is no lack of ways to measure flow!
Some of these are very precise, and some not so precise. “Accurate” is different than “precise”, as STEM graduates are fond of pointing out. A measurement of 4.25 gpm is very precise, to the second decimal…but if the actual flow going down the ditch is really 9 gpm, then the reading of 4.25 gpm is nowhere near accurate.
Anyway, how much is a gallon per minute, and a miners inch? Let’s put them in the standard units we use for agricultural diversions today. Volumes are measured in AF, or one acre of land with water one foot deep. Flow is measured in cubic feet per second (CFS). Here are the relationships:
More precisely, 1 CFS = 448.84 gpm = 1.983 AF/day, but using the rounded values above is plenty precise enough for field measurements.
What about Steve’s and Lisa’s 112 gpm, and Will’s and Roberta’s 20 miners inches? It turns out they’re both right, fortunately. 112 gpm is 0.25 cfs, close enough for horse shoes, and 20 miners inches is 0.50 cfs at the 40-miners-inches-per-cfs standard. So, Will and Roberta do have twice as big a right as Steve and Lisa, which is easy to see once the units agree!
Between the head of the ditch, or perhaps the pump, and where the water is actually used for irrigation, is the ditch itself. Ditch losses are a fact of physics and everyone has to deal with it and try to reduce it. The issue of Reasonable and Beneficial Use also comes up – a ditch loss of 10% or 20% for a mile-long ditch is pretty good, or at least acceptable, but is 80% loss reasonable? Few people would think so.
An unmaintained ditch full of grass and tules will lose more than otherwise due to plant growth. A ditch full of grass and will have lower velocity due to obstructions, and perhaps the ditch won’t convey the full right because the full flow cannot get into the ditch.
Livestock will walk across and in the ditch, which breaks down the ditch banks. This makes more water infiltrate, or soak into the ground.
Ditches get worse gradually, so that nobody notices from day to day. Some maintenance needs are obvious, some not so obvious. What are the problems that come up, and how are they fixed?
Grass and tules in the ditch – backhoe or shovel work to clean out.
Maintaining slopes – keep the ditch depth using a backhoe to take out accumulation.
Ditches get walked in, or wear through impermeable layers – the sealing has to be redone.
The head of the ditch may drop – the ditch banks have to be kept high enough to maintain head for flow.
The measurement device may wear – it has to be maintained or replaced so you know you are getting your full water right.
Maintenance alone may not be enough. Sometimes ditches have to be improved to make sure the same or more water makes it to the end of the ditch. More water can mean more acres irrigated, or more livestock, or pasture or hay making it to October instead of only to late August. How are ditches upgraded?
Fencing along the ditch banks is fairly low cost, and keeps livestock out so the ditch banks and bottom don’t get chewed up.
A liner of plastic or bentonite clay is still on the less expensive side, and can make a ditch nearly leak-proof.
A half-pipe of PVC or gunnite (sprayed-in concrete) is medium cost, is leak-proof.
A full pipe is high in cost, but there is no loss, and water can’t accidentally be “mis-diverted” by some other party.
If money were no object, or hay or livestock prices were high enough to make it worth it, then giant water guns (pivots) might water in giant circles, or wheel-lines like the one shown here would make irrigation more efficient, and make water go further, for years to come.
Why should I measure my surface water diversions if others on the same stream do not?
Installation of a device costs time and money, maybe thousands of dollars and a few days plus the use of a loader. Sometimes the unspoken question is, if I am getting more than my water right, why should I hold myself to just diverting what is legally mine? None of the readers of this blog would ask that, but some others out there might.
This is something like the question, why should I drive the speed limit if some or most of the other drivers are speeding? We have all seen the answer – speeders eventually get pulled over by police or highway patrol, while those who stay close to the speed limit generally get left alone. I’ll bet that you’re like me- I am a lot more relaxed after driving within the limits, then if I put the pedal to the metal and get somewhere an hour earlier.
50 years ago, many diversions were in the middle of nowhere and the only way there was past a protective landowner or manager. Now roads have pushed out to the middle of nowhere and so have Google Earth, recent aerial mapping, government regulations, and government employees.
In the world of water diversions, the water district, ditch tender, watermaster, or Water Board folks know who is complying with the law and who is not. The one who has a measurement device and stays within his water rights tends to get left alone. On the other hand, the law-abiding diverter gets listened to more when he or she complains that he’s not getting the water he should.
Social influence – peer pressure – also come into play after the first person on a stream installs and starts using a measurement device. The fact that a neighbor invested and did the right thing to comply with water laws encourages other diverters to do the same. Or at least, the water right holders who don’t have a weir or meter can see that it is inevitable and they’ll be more readily convinced to do the same.
Sometimes a diverter is not getting the full water right, even though he thinks he is. In this case, being able to measure the water means being able to demonstrate that when the diversion is increased, it is still within the legal amount. I have seen this happen a few times, and the result is a rancher or farmer who is a whole lot happier than he or she was last week!