Guides

Living shorelines for HOA lakes and ponds in South Florida

A living shoreline is a way of controlling erosion that relies mostly on plants and other natural materials instead of walls or rock. The term comes from coastal work on bays and estuaries, but the same idea is now offered for HOA lakes and stormwater ponds in the form of planted shelves and gentle, vegetated slopes. On a residential lake or pond in South Florida, it can protect a bank that is still in good shape, but it does not rebuild a bank that has already lost its soil.

What does "living shoreline" mean?

The National Oceanic and Atmospheric Administration (NOAA) describes a living shoreline as a broad term for "a range of shoreline stabilization techniques" used "along estuarine coasts, bays, sheltered coastlines, and tributaries." In NOAA's words, a living shoreline "has a footprint that is made up mostly of native material" and "incorporates vegetation or other living, natural 'soft' elements alone or in combination with some type of harder shoreline structure," such as oyster reefs or rock sills. NOAA's guidance also counts the Great Lakes as coast. (NOAA Guidance for Considering the Use of Living Shorelines)

The Florida Department of Environmental Protection (FDEP) uses a similar definition. An FDEP training presentation calls it "a shoreline management practice that provides erosion control benefits" and that "protects, restores, or enhances natural shoreline habitat" through the placement of plants, stone, sand fill and other organic materials. (FDEP living shorelines presentation)

Notice the words in each definition: coasts, bays, estuaries, oyster reefs. Almost all of the research and guidance on living shorelines was written for salt and brackish water, not for a stormwater lake behind a row of homes.

How does the idea apply to an HOA lake or pond?

Inland, "living shoreline" usually means 1 or both of these things:

• A planted littoral shelf. A shallow ledge along the edge of the lake or pond, planted with native water plants that slow small waves and filter runoff.
• A natural, gentle slope. A bank shaped at a shallow angle and covered with turf or native grasses, so roots hold the soil and the water meets the land gradually.

Most South Florida stormwater lakes were already designed with some of this in mind. The South Florida Water Management District (SFWMD) handbook for wet detention lakes requires side slopes no steeper than 4:1 from the top of bank to at least 2 feet below the control elevation, and it requires those slopes to be topsoiled and stabilized by seeding or planting from 2 feet below to 1 foot above the control elevation (section 5.3.2(e)). It also says littoral zone plantings "shall consist of aquatic plants native to Florida" (section 5.3.2(d)). (SFWMD ERP Applicant's Handbook Vol. II)

Palm Beach County goes further for lakes it permits in unincorporated areas. Its lake rules call for a planted littoral zone of at least 8 square feet per linear foot of shoreline, planted with at least 5 species, on a slope no steeper than 10:1, with 80% coverage within 180 days. (Palm Beach County ERM)

In a sense, many community lakes and ponds were built as living shorelines. The question is what to do when that design has worn away.

Where a living shoreline works on a community lake

A planted, natural edge does its best work in these conditions:

• The bank still has its soil, and the slope is close to the 4:1 it was built to.
• There is shallow water at the edge for plants to root in. UF/IFAS lists most emergent shoreline plants for stormwater ponds at depths of about 6 to 18 inches. (UF/IFAS ENH1215)
• Wave action at the edge is light.
• Residents have agreed to see a band of plants at the water instead of a lawn to the edge.
• The association has a budget line to maintain and replace plants.

Where those conditions hold, plants help. UF/IFAS notes that "strongly rooted emergent plants also help prevent erosion by buffering the wave action that undermines upland plant roots." (UF/IFAS ENH1215) Our guide to plants for pond bank erosion control covers which species fit where.

The limits on residential stormwater lakes and ponds

A stormwater lake behaves differently from a sheltered bay. Boards should weigh these limits before they vote.

Water levels swing through the year

Stormwater lakes and ponds are built to rise and fall. SFWMD places the wet season at about May 15 to October 15, when South Florida receives about 70% of its yearly rain. (SFWMD) A plant set at 12 inches of water in the dry season can sit much deeper by September. UF/IFAS warns that for pickerelweed, "deeper water will kill them." (UF/IFAS FP490)

Mowing and the view

Most residents bought a home with a lawn that runs to open water. A planted edge changes that view, and mowing crews have to work around it.

Steep cut banks

Once a bank has eroded, the edge is often a steep cut with a lip of turf hanging over it and deep water right at the toe. There is no shelf left for plants to stand on. Planting in front of a cut bank leaves the slope above it just as steep as before. For why banks fail this way, see why lake banks erode.

Grass carp and tilapia

Many community lakes stock triploid grass carp to control weeds, under a permit from the Florida Fish and Wildlife Conservation Commission. FWC notes that grass carp "have definite preferences for certain types of plants." (FWC) UF/IFAS adds that grass carp "browse on the tips of young, tender, emergent plants," which is exactly what a new planting is. (UF/IFAS ENH1215) UF/IFAS Extension notes that blue tilapia in stormwater ponds also feed on plant material and stir up bottom sediment while nesting. (UF/IFAS Sarasota County Extension)

Establishment time

A living shoreline is not finished the day it is planted. NOAA notes that vegetation in constructed coastal marsh sills can match nearby natural marsh "in just a few growing seasons," and that "maintenance is critical for the success of a living shorelines project, including replanting." (NOAA) Until the plants fill in, the bank behind them is still exposed to the next storm.

The Florida planting exemption: 62-330.051(12)(e)

Florida has a permit exemption written for small living shoreline projects. Rule 62-330.051(12)(e), Florida Administrative Code, exempts restoring an eroding shoreline with native wetland plants when these conditions are met:

1. The shoreline is 500 linear feet or less.
2. The plants are native wetland species suited to the site and grown commercially.
3. Plantings extend no farther than 10 feet waterward of the approximate mean or ordinary high water line.
4. Invasive and exotic plants along the shoreline are removed at the same time, to the extent practicable.
5. Only the fill needed to support the plantings is used, and the rule sets strict limits on any breakwater.

(Rule 62-330.051, F.A.C.)

Two cautions for boards. First, the exemption covers planting. It does not cover rebuilding the slope with new fill or reshaping a bank, which may need its own review. Second, an exemption from the state does not override the lake's own permit, the county's lake rules or the drainage district's requirements. Our guide to lake bank repair permits in Florida walks through who reviews what.

What drives the cost of a living shoreline?

There is no single price for a living shoreline. These are the factors that move the number:

• Length of shoreline. The total linear feet to be planted or reshaped.
• Condition of the bank. A sound bank that only needs plants costs far less than a bank that has to be rebuilt before anything can be planted.
• Depth at the edge. If the shelf has washed out, fill or reshaping may be needed before plants have anywhere to grow.
• Access. Work reached from the water or from narrow easements between homes takes longer.
• Permits and monitoring. Palm Beach County, for example, requires monitoring reports at time zero, 90, 180 and 360 days for permitted littoral plantings. (Palm Beach County ERM)
• Replacement and upkeep. Plants that die or get eaten have to be replaced every year.

When comparing bids, ask each contractor to separate the planting cost from the replanting and maintenance cost, and to state how long the survival guarantee lasts. Our guide on budgeting and phasing a lake bank repair shows how to plan for both.

When the bank has already lost its soil

Plants hold soil that is there. They do not put back soil that has washed into the lake. If the bank has a lip of turf hanging over a gap, or the slope is far steeper than the 4:1 it was built to, the slope has to be rebuilt first. Plants can then be a partner to that repair, if residents want them. Our guide on whether littoral shelves stop erosion covers this in more detail, and the repair options compared sets the choices side by side.

We rebuild the slope from the waterline up with leading edge technology so the grass roots into the bank, and we keep the work out of residents' yards. The finished bank can carry a lawn to the water, a planted edge, or both.

How to decide

Start with a record of each section of bank. Our Lake Bank Risk Score gives a quick read on where your lake or pond stands. For a full picture, book a free lake bank walk and we will measure and photograph every section. We serve Palm Beach, Broward and Miami Dade counties from Boca Raton. Call (561) 309 9603.

Questions boards ask

Is a living shoreline the same as a littoral shelf?

Not exactly. "Living shoreline" is a broad term from coastal work for erosion control that relies mostly on plants and natural materials. On an HOA lake or pond, it usually means a planted littoral shelf, a gentle vegetated slope, or both.

Do living shorelines work on retention ponds in South Florida?

They can, on banks that still have their soil, a shallow edge for plants, and light wave action. They struggle where water levels swing widely, where the bank is a steep cut, or where grass carp and tilapia graze new plants. They also need ongoing maintenance and replanting.

Do we need a permit to plant a living shoreline on our lake?

Rule 62-330.051(12)(e) exempts native wetland plantings on up to 500 linear feet of eroding shoreline, within 10 feet waterward of the high water line, if its conditions are met. The exemption does not override the lake's permit, county lake rules or drainage district requirements, so check with each before work starts.

How much does a living shoreline cost?

It depends on shoreline length, the condition of the bank, the depth at the edge, plant count, access, permit monitoring and replacement. The biggest swing is whether the bank has to be rebuilt before anything can be planted. Ask bidders to price planting and ongoing maintenance separately.

How long does a living shoreline take to establish?

NOAA notes that vegetation in constructed coastal marsh can match natural marsh within a few growing seasons. Palm Beach County expects permitted littoral plantings to reach 80% coverage within 180 days. Until the plants fill in, the bank behind them is still exposed.

Can a living shoreline fix a bank that has already washed away?

No. Plants hold soil that is still there, but they do not replace soil that has washed into the lake. A bank that has lost its soil needs the slope rebuilt first, and plants can then be added as a partner to that repair.

Sources: NOAA Guidance for Considering the Use of Living Shorelines · FDEP Living Shorelines presentation · SFWMD ERP Applicant's Handbook Vol. II · Palm Beach County ERM Lake Excavation Requirements · UF/IFAS Florida Friendly Plants for Stormwater Pond Shorelines · UF/IFAS FP490 Pickerelweed · FWC Grass Carp · UF/IFAS Tilapia in Stormwater Ponds · Rule 62-330.051, F.A.C.

More guides

• Why lake banks erode, and how to tell if yours is
• Retention pond bank repair: what boards and managers need to know
• Why regrading and sodding a lake bank does not last