The Water Board is contacting reservoir owners – maybe you too – and telling them that they have to comply with SB88 and Water Board regulations. How is that done?
First, the Water Board folks know that it takes some time to get an installation done. They will likely accept a plan to complete the installation within a year of when the reservoir owner is first contacted. The sooner the measurement device can be installed, the better for the owner’s peace of mind.
Then, how big is the reservoir? The table below from https://www.waterboards.ca.gov/waterrights/water_issues/programs/diversion_use/water_measurement.html lists how often the reservoir has to be measured, depending on its maximum storage capacity:
What is measured? Water depth is measured, and then depths are converted to storage amounts. That requires an elevation-storage curve or table, which is created when the reservoir is surveyed.
Who can survey a reservoir? You can (or I could, or Jess at Gregory Engineering Inc. can) but for all post-1914 storage water rights, it is very likely that the Water Board has already surveyed it and created an elevation-storage table as part of an Inspection Report.
How does someone get the Inspection Report from the Water Board? It has to be requested for the Application Number of the reservoir. This is the “A0xxxxx” number on correspondence from the Water Board. The email is dwr@waterboards.ca.gov. They’ll either email the Inspection Report, or send the entire water right file out to be scanned, and then the reservoir owners directly pays the scanning business to email a PDF of the scanned file. The Inspection Report is in the water right file, and will have the Water Board’s survey of the reservoir including the elevation-storage table. With that table, elevations are correlated with storage volumes, from which storage or use can be calculated with an Excel sheet.
The cheapest option to measure the reservoir depth is to measure down the face of the dam or down from the lip of the spillway, to the water. That’s on an angle that would need to be converted to vertical distances. With that, the owner has the depth and therefore the volume for any measurement. This requires a calculation to convert the measured distance to the depth, which could be done with trigonometry. It can also be done by directly measuring the slope distance and holding a construction level out to a second measuring tape from the lower end of the first measuring tape, then noting the vertical distance associated with the slope distance.
Another less expensive option is to install staff gages and read them at the required interval. Typically the 3.33-foot USGS Style “C” ceramic coated steel staff gages are used – they are durable and readable to the hundredth of a foot.
As an example, if the reservoir is 15 feet deep, then the owner would buy one staff gage that goes from 0 feet to 3.33 feet, one that goes from 3.33 to 6.67 feet, and so on, to cover all 15 feet or depth. The staff gages are attached to 2″ x 6″ boards clamped to T-posts. An optical/surveyor level is used to set each staff gage at the correct elevation so the top of the first matches the bottom of the second staff gage, and so on.
The next option is to use an electronic logger. I recommend the MX-2001 logger from Onset Computers.
Usually the 0 foot to 30 foot logger covers the necessary depths, but a 0 foot to 13 foot logger works for smaller reservoirs, and a larger reservoir might need the 0 foot to 100 foot logger. The logger is read with the Hoboconnect Bluetooth app on a cell phone. I install 2″ conduit sections screwed together, with the first section capped, and I shove them in as they are connected until the cap reaches the deepest part of the reservoir. The MX-2001 logger is purchased with more than enough cable so the transducer will be at the end of the pipe at the bottom of the reservoir, and the 11-inch data collector stays at the top of the conduit out of the water in a 12 inch x 12 inch x 6 inch NEMA box. The extra cable is coiled up in the box.
The maximum cost option is to use the Onset Computers RX-2001 telemetered station, which includes the MX-2001 logger. This can run for several years without being visited, and stores logger depths on the Onset Computers website. This is probably the least labor long-term since visits are only needed if something goes wrong.
Below are links to some posts from my blog that should be helpful: