It smells like cucumbers.

It tops out at 4 inches in length.

It is a luminous silvery blue color.

That is what a Delta smelt looks and smells like in a nutshell.

At one point the fish that have a one-year life cycle were so plentiful that they were caught and sold commercially.

Today the fish that are unique to the San Joaquin-Sacramento Delta are on the verge of extinction in the wild.

Fall trawler surveys conducted by state crews in 2014 turned up 9 Delta smelt, in 2015 it was 7, in 2016 it was 8, in 2017 it was 2, and in 2018 it  as zero.

The fish plays a pivotal role in California’s perennial water wars. Its shaky survival status has triggered orders to shut down the pumps near Tracy that send water into the California Aqueduct and Delta-Mendota Canal at pivotal points in Delta smelt’s life cycle in the spring.

When the pumps are running the Delta smelt get sucked in and killed.

The Delta smelt has also benefitted from massive releases of stored water to send more fresh water into the Delta in a bid to help them. Those releases have been criticized by farmers in the southern end of the San Joaquin Valley who argue the water is simply going out to sea and not being diverted for human uses especially during drought periods. They point to surveys of Delta smelt populations before and after such massive releases and note the decline in numbers hasn’t been slowed down.

The last four-year drought has made the situation worse for the Delta smelt.

The Delta smelt is listed as an endangered species. It is also considered an indicator species. In other words, when the numbers drop it is a sign that the Delta’s ecological system may be failing other fish as well such as the Chinook salmon.

Two factors are believed to weigh heavily on the Delta smelt’s fate. The biggest is the reduction in fresh water in the Delta since water started flowing southward via the California Aqueduct in the 1960s.

The movement of water from the north state to the south state is blamed for the overall decline of the Delta ecological system by allowing water salinity to increase. Some believe putting in place either the Peripheral Canal as was proposed more than 34 years ago by then Gov. Jerry Brown or the single tunnel plan now being pursued by the Newsom Administration would accelerate brackish conditions in the Delta hurting the Delta smelt and other fish.

With the tunnel or without, the state has indicated it wants to increase unimpaired flows on the Stanislaus, Merced, and Tuolumne rivers to send more fresh water into the Delta. Taking the water bound for Los Angeles out of the Delta ecological system by moving it below ground is expected to increase the need to replace it with water from elsewhere.

That poses a threat to those that rely on water from those three river’s watershed including the South San Joaquin Irrigation District and the cities it serves including Manteca and Lathrop.

The other threat to Delta smelt are larger fish particularly non-native striped bass and largemouth bass that were introduced to the Delta by man. Those fish bring a fourth player to the water wars centered around the Delta in addition to Delta area farmers and cities, Southern California cities and southern San Joaquin Valley farms, and environmentalists — sports fishermen.

Several scientists are predicting that the Delta smelt can’t survive in the wild given massive releases of fresh water hasn’t helped their lot.

There are Delta smelt being bred in programs the University of California at Davis operates near Stockton and at a fish hatchery near Shasta Dam managed by the U.S. Fish & Wildlife Service.

Researchers such as Peter Moyle — a professor of fish biology and associate director of the Center for Watershed Sciences at UC Davis – have pondered the question of how do we know when the Delta smelt is truly extinct in the wild as well as who makes the decision. Moyle noted the last thicktail chub was caught in Delta’s Steamboat Slough in 1957 but was not recognized as extinct for 30 years. He noted, however, that there was no official government declaration that the thicktail chub was extinct.

If the Delta smelt are declared extinct in the wild that wouldn’t necessarily mean a change in water management policies. There is a school of thought that other native fish such as the Chinook salmon, longfin smelt, green sturgeon and Central Valley steelhead have benefited from water polices aimed at assisting the Delta smelt. That’s because they view the Delta smelt as the proverbial canary in the coal mine as being the most sensitive fish to changes in Delta waterways.

The health of the ecological system and the need for water that is being commandeered by courts to help the Delta smelt is why the 4-inch fish has become — depending upon how you look at things — the poster fish for all that is wrong with California water development or the whipping fish for how state water policy has been skewed.