Moorhen Marsh: County will build natural ‘scrubber’ to reduce lagoon pollution

Indian River County has decided to build a lagoon pollution reduction project itself after bids for the project came in millions of dollars over the estimated cost.

The county commission decided in August to move ahead with the ingenious project for reducing the amount of pollutants entering the Indian River Lagoon from the North Relief Canal.

Known as Moorhen Marsh, the “low-energy aquatic plant system” located on 18 acres west of 58th Avenue will use water lettuce, a common type of floating freshwater vegetation, to absorb nitrogen and phosphorus from canal water before it makes its way into the lagoon. The two nutrients – which flow from lawns, agricultural lands, and leaky septic and sewer systems – are leading contributors to the destructive algae blooms that have plagued the estuary in recent years, killing seagrass and marine life.

Like previous successful county filtration projects such as Osprey Acres, Moorhen Marsh will use a scrubber system of natural plants to help meet state standards for nutrient loads in the lagoon imposed on counties by the Florida Department of Environmental Protection.

“It’s a more aggressive way to remove nutrients from canals,” Public Works Director Rich Szpyrka told commissioners at a commission meeting two weeks ago.

Szpyrka estimates Moorhen Marsh could remove as much as 10,700 pounds of nitrogen and 1,530 pounds of phosphorus per year from canal water flowing into the lagoon.

The county bought the land for the project several years ago. Design work is complete, and all necessary permits have been obtained. But when county officials went out to bid in June, they were dismayed that all four bids came in significantly higher than the engineer’s estimate of $10 million; the lowest bid was nearly $12 million.

In August, the county rejected all bids and decided to build the Marsh itself, settling on a process expected to lower project cost. It will purchase a dump truck and long-reach excavator to harvest nitrogen-laden water lettuce from the North and South Relief Canals; design and construct a water lettuce treatment system at the marsh site; and apply for a $1.5-million grant from St. Johns River Water Management District designated for cleaning up the lagoon.

Total cost for the project, with the county doing the work, is estimated at $9.6 million.


Related Articles

Leave a Comment