Venice weather station also saw highest wind in county
The highest water level recorded as a result of Hurricane Idalia’s effects on Sarasota County was 3.08 feet above Mean Higher High Water (MHHW), as measured at 1:30 p.m. on Aug. 30 in Venice, the National Weather Service (NWS) in Ruskin has noted in an updated report — released Sept. 22 — on the late-August storm.
The National Oceanic and Atmospheric Administration (NOAA) defines MHHW as “the average of all daily highest tide measurements.” The agency also notes that MHHW is “the best possible approximation of the threshold at which inundation can begin to occur. At the coast, areas higher than MHHW are typically dry most of the time.” NOAA adds, with emphasis, “Inundation is the total water level that occurs on normally dry ground as a result of the storm surge …”
The NWS update on Idalia also noted, “Peak water levels estimated elsewhere along coastal Sarasota County generally ranged from 2 to 4 feet above MHHW.”
Based on National Hurricane Center reports, Rich Collins, director of the Sarasota County Emergency Services Department, had warned county residents that storm surge could range from 3 to 5 feet along the coastline.
Further, the NWS update provided details about the flooding on St. Armands Circle. That area “had inundation around 1 foot into businesses and homes surrounding it,” the report said.
Additionally, the report continued, “The intersection of US 41 and Fruitville road was closed due to storm surge flooding, Casey Key Road and Manasota Key Road were washed out, and a Tiki Bar on [the] Sarasota Bayfront had its roof peeled back causing significant flooding.” The latter reference was to O’Leary’s, at Bayfront Park in downtown Sarasota.
A separate NWS report about Idalia showed that a weather station in Venice had among the 10 highest wind speeds on land that were documented during the storm. For Venice, the sustained wind was 41 mph, with a gust of 52 mph.
The highest wind speed on that list was 54 mph sustained, recorded at the Marine Science Station in Crystal River; a 56 mph gust also was noted at that site.
Altogether, the highest gust associated with Idalia at any of the NWS stations was 60 mph, at Cedar Key, the chart shows.
Among other details regarding wind, the update said, “Surface observations indicate peak wind gusts generally between 60 to 70 mph, with a maximum gust of 62 mph near Sarasota at 12:18 AM EST on August 30.”
Additionally, the update noted, rainfall ranged from 4 to 7 inches, “with a maximum total of 6.5 inches near Sarasota.”
The companion report on Idalia showed that the highest rainfall total recorded at a weather station was 7.11 inches, in Arcadia.
Further, 8,000 homes in Sarasota County lost power.
The total number of people who left their homes in advance of the storm strike and went to Sarasota County evacuation centers was 386, the report said.
Referencing information that Sarasota County Government staff released after Idalia, the report also pointed out that the damage estimate for the county is $2.7 million, with 18 structures destroyed and 1,100 having suffered major damage.
The companion NWS report noted, “Hurricane Idalia made landfall just to the north of the local area near Keaton Beach … in Taylor [County] in Florida’s Big Bend as a category 3 hurricane and brought devastating storm surge and wind impacts all along the west Florida coast, especially in closer vicinity to the landfall area across the Nature Coast. Storm surge flooding reached into homes and businesses as far south as Lee [County], and the surge inundation is the highest on record for the Cedar Key area.”
The situation on St. Armands
In regard to the St. Armands flooding as Idalia made its way through the Gulf of Mexico, Chris Goglia, president of the St. Armands Residents Association, issued a number of email blasts to members of that organization as he worked to try to determine why that barrier island suffered as it did.
In his most recent update, issued on Sept. 14, Goglia expressed his appreciation to Sarasota County Public Works Director Spencer Anderson for providing him so much information. Goglia explained, “The County is responsible for stormwater management throughout the City [of Sarasota].”
Then Goglia wrote, “At this point, the most important thing I can tell you is this: I do not think that our government failed us.”
He noted that, 17 years ago, “the City and County contributed to a $5.3M Stormwater Improvement Project on St. Armands which was designed to handle 8″ of rain in 24 hours. It was not designed to handle 8″ of rain in one hour, and it was not designed to handle hurricane storm surge at all.
“Yes,” he continued, “our pump stations failed, and yes, water was observed coming out of our storm drains … But, the system was never designed to handle what we just experienced and therefore it is just not known the extent to which the pumps would have helped, if at all. I think we all want to believe that they would have helped, and perhaps they would have, but they weren’t designed to handle this.”
Goglia explained, “We know that a vehicle accident took out the control system for one of the pumps the day before the storm. And, if I understood things correctly, one or more other pumps may also have been offline due to a delay in getting parts (i.e. supply chain challenges). Being 17 years old, the pumps are at that point in their life cycle where they need to be repaired or replaced and the County is working on this.”
Goglia continued, “If the pumps had been operational, it is unknown if they would have been powerful enough to discharge the flood water against the oncoming storm surge. They weren’t designed to do this, and therefore that is not known. The County believes that sea water was overflowing onto St. Armands and that no pumping system would have been able to keep up with that. “
He added, “It turns out that the County has an online, interactive Stormwater Management Map which shows the location of every storm drain on St. Armands Key, how they’re connected by underground pipes, and where they discharge into the bay.” He used that tool, he continued, to help create an illustration showing how stormwater is designed to drain from St. Armands.
Then Goglia listed his thoughts, based on the illustration and his communications with Anderson of Sarasota County Public Works. Among them, he pointed out that most of the pump stations on St. Armands “are located in the northeast quadrant, and this happens to be where almost all of the residential flooding that has been reported to me occurred.”
He also noted, “The Ringling Causeway toward downtown seems to me like a plausible location for sea water to have been pushed onto St. Armands, which then moved toward the Circle and down [North Washington Drive] into the northeast quadrant. The fact that several shrimp were found in an inland pool in that area may support this.”
He added, “Other parts of the island drain by gravity alone,” and county staff undertakes “monthly inspections of all the elements of the stormwater management system and has a program to repair or replace elements as needed.”
Further, Goglia wrote, “Groundwater does infiltrate the stormwater management system. The following example was given: on a sunny day, you might hear a pump station kick on as water seeps into the holding tank.
“Many of the storm drains are connected to each other via a complex network of underground drainage pipes,” he explained. “Because some parts of the island are higher than others, large amounts of water entering some storm drains could actually come out of other storm drains. Differences in pressure within the system could cause this as well.”
Goglia also pointed out, “The information that we’ve collected and learned about the recent Idalia flooding incident and stormwater management on St. Armands Key is being compiled and documented on our Association website which you can view at any time at this link: starmands.org/flooding.