City of Tracy public works officials are baffled as to why water pressure in the southern half of Tracy falls so low at specific times every summer morning. They are going to great lengths to solve this mystery, even hiring experts.

Steve Bayley, the city’s deputy director of public works, thinks the cause has something to do with residential lawn sprinklers because the dramatic drop in water pressure — from a pounds-per-square-inch reading in the mid 40s to one in the mid 30s — occurs like clockwork, exactly at 4 a.m., 5 a.m., 6 a.m. and 7 a.m. The drop lasts for several minutes, and during the rest of the hour the water pressure rebuilds until the next on-the-hour psi drop.

There might be a dual cause, Bayley says, such as with the computer program that runs the eight, 1,000-horsepower booster pumps for the south side’s waterlines. Perhaps the pumps aren’t set up to quickly ramp up when there is a big drop in water pressure.

But during the past two summers when city employees evaluated and tested every known cause, including lawn sprinklers, they have been stumped. Since they couldn’t come up with a definitive answer, the City Council has hired a professional consultant for $100,000 to spend this summer evaluating and testing the system.

By calling in outside help, is the city flushing tax dollars down the drain Not necessarily, since Tracy residents with a head of hair full of soap don’t like showerheads dribbling water. Nor do residents like a sprinkler system that doesn’t reach the entire lawn. Irritated eyes or lawns with brown spots don’t make happy water-service customers. Plus, since the mid-30s psi mark is halfway between the city norm and the state’s required 20 psi, the city doesn’t want the water pressure problem to worsen.

Whether the council’s expenditure is worthwhile depends on what Bayley and other city officials do with the new data from the consultant. If it’s an equipment problem — closed valve or plugged waterline — or a computer software mistake, the city has hard-fast remedies.

If it’s a customer problem — too many residents using water at the same moment, for example — the city will have to go into the education business so not everyone’s lawn sprinklers are popping up at the same time. That means changing consumer habits, which is more difficult than tweaking a water pump. Good luck.