WEST PALM BEACH — The health of the St. Lucie and Caloosahatchee estuaries was the topic of discussion for the July 10 workshop meeting of the South Florida Water Management District.
Both systems have been greatly altered for flood control said Drew Bartlett, SFWMD executive director.
Mr, Bartlett said neither estuary is naturally directly connected to Lake Okeechobee.
The navigation channel in the Caloosahatchee River allows the saltwater to push quickly up into the river if there is not sufficient freshwater flow to keep the saltwater out.
Based on a 30-year average, about 33% of the water flow in the St. Lucie River comes from the lake, Mr. Bartlett said.
Based on a 30-year average, flow in the Caloosahatchee River is about 26% from Lake Okeechobee, he said.
Stuart Van Horn, SFWMD Water Quality Bureau chief, said because of the structures within the lake, the water that flows west to the Caloosahatchee is cleaner than the water that flows east to the St. Lucie. The west side of the lake has marshes that help to filter some of the nutrients out of the water, he said. Based on the five-year average for Water Years 2014-2018, water flowing from the lake into the Caloosahatchee River was 98 parts per billion phosphorus. In that same time period, water flowing into the St. Lucie Canal from the lake averaged about 180 ppb phosphorus.
Water years are from May 1 to April 30. So Water Year 2014 includes May 1, 2013, to April 30, 2014, which includes a summer with heavy precipitation, he explained. Water Year 2018 includes the heavy flow of both waters and nutrient load into Lake Okeechobee following Hurricane Irma.
St. Lucie Estuaries
On the average, based on Water Years 2014-2018, the flow to the St. Lucie came from:
• Lake Okeechobeec 31%;
• C-44 Basin — 12%;
• C-23 Basin — 12%:
• C-24 Basin — 12%
• Ten Mile Creek Basin — 10%;
• Tidal basins — 23%.
For that same time frame, phosphorus loads into the St. Lucie estuary were:
• Lake Okeechobee — 23%;
For that same time frame, nitrogen loads into the St. Lucie estuary were:
• Lake Okeechobee — 36%;
• C-44 Basin — 13%;
• C-23 Basin — 14%;
• C-24 Basin — 14%;
• Ten Mile Creek — 7%;
• Tidal Basins —16%.
It was noted that due to the unavailability of USGS data, USACE flow volumes reported for Oct. 8 through Dec. 6, 2017 (the high-flow period following Hurricane Irma), appear to overestimate contributions from Lake Okeechobee and underestimate C-44 Basin runoff.
On average, based on Water Years 2014-2018, flow to the Caloosahatchee came from:
• Lake Okeechobee — 38%;
• C-43 Basin — 44%;
• Tidal Basins — 18%.
In that same time frame, phosphorus loading the Caloosahatchee came from:
• Lake Okeechobee — 30%;
• C-43 Basin — 58%;
• Tidal Basins — 12%.
The nitrogen loading to the Caloosahatchee during that period was:
• Lake Okeechobee — 40%;
• C-43 basin — 46%;
• Tidal Basins — 14%.
The Caloosahatchee River receives flow from Lake Okeechobee during the dry season to prevent saltwater intrusion in the river.
The public comments period at the meeting included a broad range of water quality concerns.
Dr. Bill Louda with Florida Atlantic University said he has been studying the Taylor Creek/Nubbin Slough area in Okeechobee County, which has been a hot spot for nutrient loading for decades.
“Taylor Creek is a cesspool,” Dr. Louda said, with apologies to those who live there. He said he supports Okeechobee Utility Authority’s proposal to put that area on sewer lines and hopes it is funded.
Dr. Louda said he is tired of people talking about problems from “leaking” septic tanks.
“All septic tanks pollute,” he said. The grass is not greener over the septic tank, he added. It’s greener over the drain field.
Gary Ritter of Florida Farm Bureau said it was brought up in the Blue Green Algae Task Force meeting, that urban and agricultural Best Management Practices “can’t get us where we need to go. We need regional projects.
t almost 80 percent reduction in those discharges,” he said.
He said the Taylor Creek/Nubbin Slough watershed, which has historically been a hot spot for nutrient loading, has been a challenge to keep STAs hydrated. ASRs could keep those STAs hydrated during the dry season.