Record-breaking Rainfall Sends Guts Overflowing, Rocks Sliding

Runoff at Maho Bay, above, eroded the beach and sent sediment into the bay.

With waterfalls gushing, guts overflowing and rockslides wiping out entire lanes on several St. John roadways, Love City looked more like Soggy City last week.

As of Friday morning, July 23, 12.46 inches of rain had accumulated at Trunk Bay during the month of July alone, according to Rafe Boulon’s rain data.

Boulon, the chief of resource management at V.I. National Park, has been collecting rain data at his North Shore home since 1983 and this month was the wettest July he has ever recorded.

On Tuesday, July 20, alone Boulon netted two inches between 3 and 4 p.m., which sent rocks and mud cascading down already saturated hillsides.

“Hawksnest Gut was four feet deep during the heaviest rainfall,” said Boulon. “It usually recedes pretty quickly, but when I got there around 4 p.m. it was down to about three feet.”

Before this July’s more than 12 inches of rain, the most rain to fall during the month of July was a measly 6.68 inches, which Boulon recorded in 2005.

As anyone who has spent time on St. John over the past few months can attest, the rains didn’t start in July. Even back in May, Boulon was collecting near-record amounts of rain.

May 2010, with 10.6 inches of rain, was the second wettest May Boulon has ever recorded. June’s accumulated 7.48 inches of rain was the wettest June Boulon has seen since he started collecting precipitation data.

Going into the month of July, St. John had already seen almost 10 inches more than usual for that time of year. As of Friday, July 23, a total of 41.89 inches of rain had fallen during 2010 so far and the average yearly rainfall for St. John is only 43 inches.

“It’s just been a wet year,” said Boulon. “May was the second wettest May since I started collecting data in 1983, June was the wettest June and we’re already well past our average for July.”

The rainfall set back North Shore road repairs, hampered the work of V.I. Water and Power Authority’s Estate Grunwald power line crew and closed one lane near the Cruz Bay tennis courts for most of the early part of the week.

Along with the lush green hillsides, so much rain accumulation also often means lots of mosquitoes and a greater danger of contracting dengue fever. There have already been two reported cases of dengue fever on St. John, with more possible.

While standing water, where the dengue fever carrying Aedes egypti mosquitoes often breed, can pose dangers, such a heavy amount of rain usually bring less mosquitoes, according to Boulon.

“Sometimes when we have these big gut washes, like this, it flushes everything out,” said Boulon. “The mosquitoes that have already laid their eggs will be washed out, which we saw in May and June. During those months we didn’t really have any mosquitoes.”

“And I think that was because there was a continual flushing of the eggs and larvae,” Boulon said. “When it stopped raining a bit at the end of June and early July, when it tapered off for the a week, that is when we started getting more mosquitoes.”

The Department of Health has already started fogging for mosquitoes on St. Croix and St. Thomas and plan to start soon on St. John. DOH, however, had not set a date for fogging as of press time.