Guest blog: The Caloosahatchee Conundrum

 
Brown water loaded with nutrients descends on the waters around Sanibel Island, FL.

A message from Florida-Alabama coastal organizer Christian Wagley:

In order to realize a healthy and restored Gulf, GRN relies on thousands of people and organizational partners in communities all along the Gulf coast. Our friends in Southwest Florida are experiencing another epic tragedy as massive flows of freshwater are being diverted down the Caloosahatchee River to the coast to keep inland farms and communities dry. These massive flows cause major impacts as salinities drop and the growth of algae explodes, causing a cascade of negative impacts to waterways. Rae Ann Wessel of Sanibel Captiva Conservation Foundation brings us an update from the field, in The Caloosahatchee Conundrum.

The Caloosahatchee Conundrum

Record setting rainfall the last 2 weeks of May, 2018 flooded the entire Greater Everglades region. Since the rain began, the Caloosahatchee estuary has been experiencing increasing levels of harmful flows.

Flows the first 2 weeks originated from watershed runoff, with no discharges from Lake Okeechobee. Lake discharges began on June 1, 2018 and nearly tripled the harmful high flow threshold to the estuary, (over 5.3 trillion gallons/day) dumping dark colored, fresh water causing a sudden drop in salinities over 33 miles of estuary, out to the Gulf of Mexico.

Estuaries are adapted to adjust to short term extremes but not for extended periods. Estuary and marine organisms and their habitats in the Caloosahatchee experience harm from high flows that cause a sudden drop in salinities when freshwater flows at the Franklin lock reach 2,800 cfs (1.81 trillion gallons/day).

The consequence of the sudden, drastic salinity drop - now in its 4th week- has been an observed die off of estuarine clams and oysters at Iona just upstream of Shell Point. High flows cause low oxygen, increase nutrient loading fueling freshwater cyanobacteria/bluegreen algae, that has exploded over 58 miles (77%) of the river from Lake Okeechobee to the middle estuary.

The Set Up - Hurricane Irma 2017

Following Hurricane Irma in September 2017 the estuary was blasted with harmful, high flows through December. Within 30 days water managers decided to decrease dry season lake flows to the Caloosahatchee causing salinity levels to increase to levels exceeding the ecological harm standard of 10 psu at Fort Myers. For three months, water managers withheld needed freshwater despite lake levels remaining harmfully high. This decision was made in spite of clear evidence that the estuary needed water, there was sufficient water in the lake to meet all agricultural and other water supply demands -even if the rainy season started near the end of June.

The 2018 High Flow Event

So why did they hold back needed water when it was available? Because water management policies prioritize private consumptive use permits for water over the health and welfare of public resources like estuaries. Likewise, agricultural landowners

benefit during flooding conditions by moving floodwater off their lands into other already flooded systems, even when it causes harm to public resources.

In this event the first discharge to the estuaries equaled the agricultural stormwater dumped into Lake Okeechobee. Had they held that water on their own lands flooding impacts would have been shared.

Solutions

Lessons learned from this event:

 Agricultural backflows into the lake exacerbate high lake levels and deliver unwanted nutrient loading that triggers harmful estuary discharges. The backflows accounted for 98.5% of the water discharged to the estuaries.

 There was capacity in the lake to absorb the early rain event. It was premature to dump massive quantities of water to the estuaries at the very beginning of the rainy season when no water was being held by or discharged to agricultural areas to share the harm

 If water managers had not starved the Caloosahatchee of needed freshwater flows for the four previous dry months, the lower lake would have had even more capacity to store water.

 Stormwater from farms has been allowed to use up nearly all the storage and treatment capacity of the taxpayer funded stormwater water treatment areas (STAs) and Water Conservation Areas (WCAs) built to take and treat Lake Okeechobee water. Agriculture is allowed to shift their stormwater off their land to public infrastructure.

The operational protocols for managing water must change especially as we face more frequent extremes in weather variability and impacts from sea level rise.

Rae Ann Wessel

Natural Resource Policy Director

Sanibel Captiva Conservation Foundation

 

 

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