This is an update from my earlier post on my recommendation for a durable, set-it-and-forget-it water level logger. Some kind of device is necessary to meet Water Board requirements; daily data must be recorded July 1, 2017 for those diversions of 100 to 1,000 acre-feet per year, and hourly data must be recorded starting January 1, 2017 for those 1,000 acre-feet and higher. These roughly correspond to minimum irrigation season water rights of 0.37 to 3.7 cfs, and 3.7 cfs and higher.
To review, here is the Water Board’s table of measuring and monitoring requirements. I added the 2 columns on the right to show the approximate water rights and year-round flow in CFS:
The PMC guys had to make a change in the sensor, so now the recommended setup is the PMC Versaline VL4511 – WLS-31 Water Level Datalogger. It will cost the same and be as durable. Regarding the reason for the change, 
Bob Foster at PMC wrote: “This system will come with our VL4511 level sensor and not the VL2000 that we initially spoke to you about.
The reason for the change is the VL2000 required slightly more power than what is available through the datalogger battery, so we decided to provide an upgraded sensor model, which uses much less power.
This upgraded sensor, our VL4511 also has the advantage of using:
- An all-welded Titanium housing, which has a 5-year corrosion warranty
- Significantly smaller diameter
Additionally, it still has anti-clog features near the sensing element to ensure reliability.”
I also asked Bob about battery replacement. Some well-known loggers have to be sent back to the manufacturer to have the batteries replaced. The battery lives are 1 to 2 years. What about the PMC Versaline VL4511 – WLS-31?
Bob reassured me that the PMC unit’s batteries are replaced in the field, by the landowner, or the engineer or technician acting for the diverter. Battery lives are still only 1 to 2 years. However, the batteries are inexpensive, about $7 each. That keeps your costs and hassle to a minimum.
What about expected maintenance at the manufacturer? While some better-known data loggers typically have to be sent in every 2 to 3 years, the PMC unit is expected to need no manufacturer’s maintenance for 10 years!
This post is about the PMC Versaline VL2111 – WLS-31 Water Level Datalogger. This looks much like the Global Water WL-16, but instead of a silicon bladder at the end of sensor, it has a non-fouling ceramic sensor. At $1,370 before tax and shipping, it has a higher purchase cost than some alternatives, but it is my recommendation for durability, reliability, and low maintenance.
The Versaline is made for wastewater; in other words, for sewer lines. The datalogger end is vented and it is not supposed to be submerged. However, it is made to put inside manholes where it is very warm and humid. The PMC guys have maintained the sensor end in rough environments with the equipment lasting 8 to 12 years. If the sensor gets completely covered with algae (or something worse), it still works. It can be cleaned off with a toothbrush if it seems so clogged it might prevent water from getting to the ceramic end. The data logger and sensor are fairly new but are improvements on the older, long-lived versions.
The VL2111 – WLS-31 is three times the cost of the least-expensive option that I have seen so far. However, it might be the least expensive in the long run…it sure is the most worry-free of all the options listed here!
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