Pop quiz: Where is the saltiest place on earth?

It might surprise you to learn that it is in Antarctica’s McMurdo Dry Valleys –  specifically, Don Juan Pond.  Though the pond is only ankle-deep, it holds the record for the highest natural salinity with a salt concentration that can reach up to 44%. This is about twelve times saltier than the ocean, and significantly saltier than other famous hypersaline bodies like the Dead Sea.

Don Juan Pond’s extreme salinity is primarily due to its high concentration of calcium chloride. Fun fact: This allows the pond (which looks more like an oversized puddle) to remain liquid even in temperatures as low as minus 58°F . The hypersaline environment is so inhospitable that it serves as a model for astrobiologists studying potential life on Mars where similar briny conditions may exist.

We mention Don Juan Pond as a segue to how dogs are helping sniff out saltwater ingress issues in wastewater networks like Sydney, Australia’s Kogarah Bay.

In Kogarah Bay, salty ocean water sometimes leaks into the pipes that carry dirty waste water away from homes. Salt water can quickly rust and damage the pipes, making them break or wear out faster. It also makes it harder and more expensive to clean the dirty water so it can be reused. Too much saltwater also harms local plants and animals that live in the bay.

Cue the dogs.

In 2020,  specially trained scent-detection dogs were brought in to sniff out instances of saltwater intrusion in wastewater tunnels. The pair, “Winnie,” a Cocker Spaniel, and “Ziggy,” a Springer Spaniel, had been specially trained to recognize the unique smell of saltwater mixed with wastewater.  Once on site, the dogs made short work of searching large areas and marked the spots where leaks were happening, even if humans hadn’t noticed visible signs or strong smells. The dogs’ findings were doubled checked by Sydney Water crews who used the information to repair the pipes and stop the leaks.

In just one and half days, the dogs inspected about 1.55 miles of ground and flagged 15 possible locations for saltwater ingress. Of these, seven locations were confirmed as actual leaks using smoke-testing, while another six required further investigation. Bottom line: Winnie and Ziggy’s initial detection had a high success rate, with nearly half of their alerts immediately verified as real leaks and most of the rest considered likely enough to warrant more testing.

The smell of saltwater + wastewater is different from fresh water or regular ground smells, of course. The spaniels had been introduced to the target scents in a controlled setting such as using scent containers or boxes with samples of saltwater-soaked material and positive reinforcement when the dog found the right box. Once the dogs reliably identified the scent in training, they were taught a clear signal behavior to let their handlers know exactly where the leak was. In time, the dogs practiced searching in more challenging environments such as tidal zones (and for anyone wondering, tidal zones in estuaries are dangerous environments for detection dogs and their handlers, so the dogs are trained to wear high performance protective boots, allowing them to work and track among sharp oyster clusters, slippery rock platforms, and broken glass).

One might wonder why spaniels were thought to be better than traditional scent hounds such as a Bloodhound or Beagle. In fact, in an article appearing in Australia Water Association’s website, Nicole Harvey, a trainer and handler with the Sydney Water Dog Detection Team, said that breed detection was vital when putting together a successful working dog team; springer spaniels and cocker spaniels were hand-picked from from successful hunting line, field-trial champions and conservation dogs because they are incredibly versatile, have high energetic, and are bred for exceptional scent and tracking abilities.  Other breeds that tend to be highly food motivated can make training and on-site work more challenging than spaniels who have a high play drive and are motivated more by toys and games.  The size and agility of spaniels also makes them well-suited for navigating tight spaces, uneven terrain, and areas with lots of obstacles typically found around water and sewer infrastructure. Dogs begin nine months of training before their first birthday and the results prove their success rate.

Sydney Water is Australia’s first water utility to employ wastewater leak detection dogs, and Winnie and Ziggy are a testament to using dogs to solve modern problems. In 2021, Sydney Water added “Joey” to its team. Joey is the first drinking water leak detection dog and can sniff out hidden underground leaks that humans might miss.

Photo of working spaniels by cgandy425/iStock (they are not Winnie and Ziggy)