Key Largo canal could get go-ahead for restoration

A Key Largo oceanside canal ranked “among the worst as to water quality in the entire county” stands in line to become the next waterway restoration project in Monroe County’s test program.

“The residents there say have seen a very steep decline in water quality over the last 20 years,” county Sustainability Program Manager Rhonda Haag said. “They don’t see fish anymore. They don’t see anything.”

The canal between Grouper Lane and Bonito Lane, near mile marker 95, has been reviewed by biologists and a ranking committee for inclusion in the county’s $7 million canal restoration program that tests various types of fixes for problem canal systems.

County commissioners, meeting Wednesday in Key Largo, will be asked to allow staff to begin negotiations with Adventure Environmental, which submitted a $1.6 million bid on the project designated as Canal No. 83. Two other companies submitted bids of $1.54 million and $1.73 million. Adventure Environmental handled previous canal projects similar to this one.

If approved, the Key Largo canal would be the first in the county’s pilot program to remove an overall average of two feet of organic muck on the canal bottom, then place fill to reduce the canal’s depth.

Manmade waterways dredged too deeply — once a common practice to obtain fill for low upland areas — do not allow light penetration to the bottom. That creates troublesome environmental conditions. When winds are right, seaweed and other organic material are pushed into the canal, they were decay and sink to the bottom. Without adequate light, the material decays into muck, a process that sucks oxygen from the water.

“The presence of the muck in this canal has depleted the dissolved oxygen levels in the canal waters, and the removal of the muck and subsequent backfilling to enhance natural flushing will help to restore the canal waters,” a project summary says.

Previous canal restorations have backfilled a deep canal, and removed organic muck. Canal No. 83 will be the first to combine muck removal with backfilling. An air curtain would be installed at the canal entrance to reduce seaweed entering the canal.

“It’s still a demonstration program so the canals will be monitored for two years to see if there are differences,” Haag said.

If commissioners agree, the new project could begin before the end of the year. Actual work is expected to take about 120 days.

In a related item, commissioners hold a public hearing is scheduled for 3 p.m. Wednesday on a permit that would allow an undeveloped Grouper Lane lot to be used as a temporary staging area for the work.

The canal restoration program was launched to determine the most effective means of dealing with waterways suffering from poor water quality, in hopes that would lead to state and federal grants for additional efforts to protect nearshore waters.

Wednesday’s meeting takes place at the Murray E. Nelson Government and Cultural Center at mile marker 102.

This story was originally published September 17, 2016 at 9:41 AM with the headline "Key Largo canal could get go-ahead for restoration."