There have been 25 posts so far, on the types of California surface water rights, flow measurement devices, and how to measure diverted flows. You’ll see new posts once or twice a week.Please send suggestions for post topics! We have discussed:
So on Tuesday, January 20, “The State Water Resources Control Board (State Water Board) adopted regulations Tuesday evening requiring all surface water right holders and claimants to report their diversions. Those who divert more than 10 acre-feet of water per year must also measure their diversions.” Click the logo above to see the 2-page document on the Board’s website.
Well, how bad can it be? Before January 20, most diverters had to report monthly diversions, so 12 volumes per year, plus the annual total. That’s 13 numbers. The required frequency a year from now will be increased quite a bit, to weekly, or daily, or hourly:
“For instance, large diverters with a claimed right to take 1,000 acre feet of water or more per year are required to have a measuring device or measuring method capable of recording at least hourly in place by Jan. 1, 2017; those with claimed rights to divert 100 acre feet or more must comply by July 1, 2017 and record at least daily; and those with claimed rights to divert more than 10 acre feet must comply by Jan. 1, 2018 and record at least weekly.”
How can flows even be reported hourly? See the end of this post. What if someone decides to skip reporting, and let the Board catch up with them later? The FINES can be large enough to hurt – we’ll discuss this in a later post.
At the minimum reporting requirement of weekly, the volume is 10 acre feet (AF) to 100 AF. What is 10 AF in terms of a seasonal agricultural diversion? All the flows shown below are year-round; if the diversion only runs seasonally, the actual water right might be 2 to 10 times the calculated amount, depending on how long the season is and when the stream dries up.
10 AF = 0.014 cubic feet per second (cfs) year-round, or 6.2 gallons per minute (gpm). That’s a domestic right, enough for a family house, garden, and perhaps 15 trees or a yard.
100 AF = 0.140 cfs, or 62 gpm year-round. Depending on soil, this is enough for 3 to 15 acres of pasture or hay, maybe 15 cows or steers, or maybe 30 acres of a mature walnut orchard with micro-sprinklers. This is enough for a little extra money, still not enough to support a family.
1,000 AF = 1.40 cfs or 620 gpm year-round. This is enough for 30 to 150 acres of pasture or hay, or maybe 300 acres of orchard. Water in this quantity could support a family and would be considered a ranch or farm. The 4′ weir above has about 1.4 cfs going over it. As mentioned above, if this diversion only runs 6 months of the year, and really only gets the full flow for 3 months, then the actual continuous water right might be 5 cfs. It might be easier to reverse the thinking: a 5 cfs right might run at 5 cfs for 3 months, 3 cfs for a month, 2 cfs for 2 months, and be off the rest of the year. That’s closer to a 2 cfs right year-round, or about 1,400 AF per year.
How is flow measured HOURLY? The only practical ways to do this used to be an old mechanical recorder, like a Stevens F Recorder (pen on paper on rotating drum) you can still see on some creeks.
More likely today, it will require a battery-powered pressure transducer set inside a 2″ pipe bolted on the side of the weir, or headwall, or other permanent structure. These cost from $400 to $1,200 or more, depending on the brand and more importantly, quality. The higher the quality, the less they have to be checked, and have dirt removed from the bottom sensor. The maintenance can be significant – in warm water with algae, the sensor might have to be cleaned once a week. If it’s not maintained…well, then at some point it stops recording that data that the Board requires.
Here’s one that would do the job, from http://www.globalw.com/ products/levelsensor.html. It sits there and records water levels night and day, for months at a time before it has to be downloaded to a computer. The data file that is downloaded is what is actually sent to the Board – a spreadsheet of flows for 6 months would be half an inch think and unusable!
This is a corner of a diversion box built by my wife’s grandfather, Emil Wigno, in 1922. The fleur de lis he brought with him from France. 🙂 Emil planted hay, peaches, prunes, and finally walnuts.
Hi, I’m Shawn Pike. 🙂
Now 2″ x 6″ boards, cut 1/2″ to 1″ shorter than the width of the board slots, are stacked up in the diversion box.
The weir board is cut 3-1/2″ deep. There are 2 weirs, one 1.0′ wide, and the other 0.5′ wide. These are contracted weirs, since water on the edge has to turn to go through.
The small weir is blocked off, so the 1.0′ weir is left. This is a 1.0′ contracted weir, and the flow can be read right out of the correct table in the Water Measurement Manual.
By simply flipping the weir board upside down, we have an orifice! If the downstream water is higher than the hole, then the orifice is “submerged”. If the flow out the orifice is free-flowing, then a different equation is used. Either way, calculating the flow is pretty easy because we know the orifice area, and depths of water upstream and downstream.
Here’s the pretty photographer and videographer, in the gold-mining town of Bodie. 🙂
What is a flume? Most people think of long flumes that carry water across a canyon, or along the edge of a mountain, to get water through steep country. These flumes are expensive and time-consuming to build so they have to make economic sense. In early
California, flumes were used to get water from a stream to gold-bearing gravels where there wasn’t water. Gold was certainly worth the expense! It takes water to wash gravel over a washboard so gold can settle out in the ribs or slats. Flumes were then used to transport cut logs from the mountains down to mills in the valleys. Lumber also brought in enough revenue to make flumes worth it.
The kind of flume for measuring flows is a concrete, metal, fiberglass, or wood structure built to exact dimensions. The newly-built flume shown below is formed concrete. It took 4 days for a crew of 5 people to make this. This flume is 3.0′ wide, and will be used to measure diversions of up to about 16 cfs. This device could last for 40 years before it becomes too worn to be accurate, or develops cracks that let parts of it settle.
Flumes are much more expensive than a weir box with boards. It costs 3 or 4 times as much to install. On the plus side, there are no boards to change, it measures a wide range of flows with good accuracy (+/- 5% in the first 10-15 years of its life), and it will pass debris and gravel through without clogging.
The photo below is of a flume that has been installed for 30 years. It shows what can become a common problem: the ditch below has not been kept as deep as it should be, so the flume is “flooded out”. The flow computed by using the staff gage depth is about 40% more than actually goes through the flume…so the ranchers who use the water could be shorting themselves.
Rehabilitating a flume is not impossible, but it is not often done. The whole floor could be raised by pouring a higher concrete floor, making sure it slopes exactly the way the old floor sloped. Usually a new measurement device is installed nearby, and the old flume is not used anymore.
More on the details and how-to’s of flumes later. For now, we sure appreciate the snow and rain!
Worried about SB 88?That’s what this blog is for!Read here to select a flow measurement device, install it, send a photo to the Board, record your flows, and report them as required. You will find most or all of the information you need in here. If you need help, Rights To Water Engineering can help you meet the law quickly and at a relatively low cost. (530) 526-0134
California Senate Bill 88 is effective as of January 1, 2016, 11 days ago as of this posting. Here is the part that affects private or small agricultural diverters the most:
Is John Stealing Water?? John Casey has a cattle ranch near Adin, where he grows pasture and hay to raise about 70 Angus steers. His place is 240 acres with lower irrigated land and forest on the higher part. He has an adjudicated water right of 2.00 cubic feet per second (cfs) from Preacher Creek, to irrigate 80 acres.
John’s downstream neighbors claim he steals water. He says he can show that he takes only 2 cfs, or less when the flow drops down in the summer. Can he prove it?
As we can see, he has a square headgate at the head of his ditch. It is 2.0′ wide, and can open up to 1.5′ high. Right now, John says he is diverting 1.05 cfs. His evidence is that his gate is open 0.15′, the water is 0.57′ deep on the upstream side, and the water is 0.20′ deep on the downstream side. Is that enough to check what he says?
The box in which the gate sits has smooth walls, and the gate closes flush with the bottom when John is not diverting. The water continues in a straight path from upstream to downstream. That means the weir has “suppressed” sides.
This is in contrast with, for example, a hole cut in the middle of a 2″ x 12″ weir board. The water on the sides has to make the turn to go straight through, so the hole in the board is an example of a “contracted” orifice.
Let’s look at the tables for orifices in the back of the Water Measurement Manual. Table A9-3 is for submerged, suppressed weirs.
We can’t see the downstream side of the weir, but the water is above the bottom of the edge of the gate, so it is submerged rather than free-flowing.
This table has flows calculated for a minimum area of 2.0 square feet (sq. ft.). However, the area of the opening at John’s headgate is 2.0′ wide x 0.15′ high, or 0.30 sq. ft. Fortunately, the equation, Q=0.70A(2g Δh)^0.5, is listed right at the top of the table. We can calculate the flow using that. Q is the flow in cfs, A is the area of the orifice hole, g = the acceleration due to gravity, or 32.2 ft/second^2 (feet per second squared), and Δh is the difference between the upstream and downstream water depth.
So the flow Q = 0.70 x (2.0′ x 0.30′) x (2 x 32.2 x 0.37′)^0.5 = 1.03 cfs. So far so good – John is taking 52%, or just over half of his right when 100 percent of flows are available. But, how much flow is actually available right now?
Let’s use the “sum of the boxes” method. Instead of measuring the amount of water in Preacher Creek at the top, before any diversions, and then estimating how much flow is being lost to evaporation, transpiration, and infiltration, and then estimating how much flow is subsurface above John Casey’s ranch and “pops up” out of the ground below, we’ll look at what each diversion amount is, plus the amount still in the creek after the last diversion. This is very useful because none of the instream losses have to be estimated – we just add the diversions and flow still in the creek, and that amount IS the available supply. Some Superior Court judges in past decades were pretty smart and actually ordered that available flows be calculated this way.
The paragraph above, from the Susan River Decree, defines available water supply as what is being diverted, plus the flow passing the last diversion.
There are 4 diversions on Preacher Creek, and here are the amounts being diverted:
Diversion 1 (John Casey) 1.03 cfs of a 1.60 cfs water right, 52% of his total right
Diversion 2 (Amy Hoss) 1.67 cfs of a 3.80 cfs water right, 44% of her total right
Diversion 3 (Mark and Cindy Sample) 0.55 cfs of a 0.88 cfs water right, 62% of their total right
Diversion 4 (Quint and Marcie Minks) 1.32 cfs of a 2.50 cfs water right, 53% of his total right
Flow still in the creek past the Minks Diverison – Quint estimates about 0.7 cfs
The total diversion-plus-bypass flow is about 5.3 cfs. The total rights on the creek are 9.48 cfs. Therefore, the total available flow = 5.3 / 9.48 = 56%.
So, John is right, he is not stealing water! He is taking 52% of his water right, when he could be taking 56% according to the “sum of the boxes” method. Not only that, but Amy could take more, the Samples should reduce their diversion, and the Minks’s could take a tad more. Well, that’s theoretical – Quint and Marcie Minks probably cannot seal up their dam completely, so there may be a little bit less flow actually available for diversion.