Why Doesn’t The Water Board Use Satellite And Aerial Imagery To Track Diversions And Storage?

Here is an email exchange I recently had with Kathy Mrowka at the Water Board.  Enough folks have asked me that I had to ask, and Kathy has a short and sensible answer.  Her answer will be frustrating to some, and a relief to others; either way, it represents the state of technology today as well as legal requirements.

From:  Shawn Pike

To:  John O’Hagan, Kathy Mrowka, and Jeffrey Yeazell

“Hi John, Kathy, and Jeff,

“Several intelligent ranchers have asked me, why doesn’t the Water Board just use satellite imagery to monitor flow and water storage?  I did not have a good answer why not, since high-resolution satellite imagery has been available for more than 40 years, and very high resolution aerial photography is taken with exponentially increasing frequency.

“It is common knowledge that the Water Board has used aerial photography to find thousands of reservoirs and stockponds.  The Department of Water Resources has used aerial photography and some ground-checking to map land and water use, including estimates of applied water, for decades.

“I’ll bet some inventive brains at your place are making progress on using photography to monitor and quantify water flow through diversions, as well as impounded water storage.  Given that increasingly detailed data are derived from photography, farmers and ranchers are very interested in having DWR and/or the Water Board use the same technology to monitor diverted flows and storage.  It would be a heck of a lot less expensive – a few percent of the thousands of dollars each diverter now has to spend on measuring devices, data loggers, and reporting their diversions.

“Do you have some good news to pass on to individuals, the Farm Bureau, Cattlemen’s Association, and others?

“Thank you,


Kathy’s answer:

“The Department of Water Resources and others, including the State Water Board, utilize satellite imagery for ground-checking information.  The imagery can also be used with other models for estimates of applied water.  An estimate of applied water unfortunately, does not provide the total amount diverted from the source.  For instance, where delivery is by long irrigation canals, the water diverted to account for canal losses is greater than the amount applied for irrigation.  Aerials also cannot distinguish between water supplies from groundwater wells, purchased supplies and diversions of water from a stream.  A water right is issued for a specific diversion amount and season and measurement of the diversion is necessary to quantify the amount diverted under the specific water right and priority (which can include reasonable conveyance losses) from the amount consumed or estimated as applied water.  We believe the measurement of diversion is important.  Additionally, the diversion information combined with satellite imagery can help ensure water diversions are reasonable. 

Kathy Mrowka”


Ponds – How To Measure, Record, File…Including Alternative Compliance Plans

I have delayed posting on reservoirs and stockponds, and then work for clients got really busy.  Several recent clients have been ranchers and farmers

     Pond – photo credit: publicdomainfiles.com

 with small stockponds, sometimes many small ponds.  What has to be measured, how can it be done economically, what needs to be filed, and how can someone get an exemption to the strict SB 88 law and Water Board regulations?

Ponds over 10 acre-feet (AF) have to be measured, and volume data recorded somehow.  Here’s the table from the Water Board:

Water Board Diversion and Pond Measurement Installation Deadlines, Accuracy, Data Recording Frequency, and Qualified Person

The measurement device can be as simple as 2 – $410 Onset Hobos (delivered costs), for $820 total, or more durable In-Situ Troll 200s, $700 each delivered, $1,400 total. If the owner wants to download them and run the software, that’s another $350. The water level logger in the water can be put in a capped piece of 2″ galvanized or PVC pipe, a rope tied to the pipe,

 with a buoy on the other end, and then dropping the pipe at the deepest part of the pond. It takes a boat of some type to install it, and pull it up every 6 months or so to maintain and download it. The water level logger device is the same whether the data recording frequency is monthly, weekly, daily, or hourly – the user sets the recording frequency using the proper software.

What has to be filed?  Your annual Statement of Diversion and Use, for a pre-1914 and/or a riparion water right.  A Report of Permittee or Licensee, for a post-1914 water right.  Does something else have to be filed because you installed one or more new measurement devices or data loggers?  Yes, you will need to file a Measurement Method form, or have it filed by a qualified person.

     Pond In Mountains, Photo Credit: Pixabay

Measurement devices are required by SB 88.  The only exception is if an Alternative Compliance Plan (ACP) is filed with the Water Board.  ACPs can be filed for one or more of four main reasons:  1) Standard measurement is not feasible; 2) Measurement would unreasonably affect public trust resources (including fish, wildlife, recreation, navigation, and aesthetic values); 3) Measurement Is unreasonably expensive (requires complete supporting documentation; and 4) Measurement would result in the waste or unreasonable use of water.

ACPs are not evaluated, approved, or denied by the Water Board.  However, they will all be filed on-line, available for the public to see.  An individual, group, or agency might protest part or all of an ACP, and then the Water Board has to decide whether the protest is reasonable.  The end result could be no action, or the Water Board calling the owner to suggest measurement devices are needed.  If suggestions are not followed, then the Cease And Desist Order would be sent, demanding either compliance in 30 days, or fines of $500 per day until compliance is done.  In summary, there is no guarantee an ACP will stand up to criticism.

ACPs need a lot of information filled in, and a good narrative of why standard measurement does not apply.  There should be an ACP for each diversion, and each pond.  Hint:  a ranch can have one ACP to cover all the ponds, using the same text for each filed ACP.

What kinds of ACPs are likely to succeed?  The bureaucratic answer (and I used to be a bureaucrat) is plans that clearly fulfill one or more of the four conditions listed above; that are well-described so any reader can understand it; and which have little or no environmental influence.

For ponds and reservoirs, what kinds might reasonably be in an ACP.  There is no blanket answer!  However, a remote 20 AF pond, with fire danger in the summer trying to drive to it, or inaccessible in the winter, might fit.  Ponds with no controlled outlets, that have only spillways and do not fill by any human action, might fit.  That’s all I am willing to venture here.  For help, see a qualified individual who can provide expert help!