Dredging Continues for Tidal Circulation Enhancement in San Elijo Lagoon

If you live near the lagoon, or visited the Nature Center last week, perhaps you wondered: What are those big new berms? And this morning, you may wonder: Where did they go?

As seen below, two temporary construction berms, or water control features, were constructed last week to help control water levels as crews prepare to install the actual 2B dike (see map).

Prepping for dike installation_1

Pictured above: This berm was under construction beginning last week.

Prepping for dike installation_2

Above: This berm was constructed of lagoon sediment.

On the evening of Saturday, June 23, a 5.7-high tide had other plans and pushed through the temporary berms, filling the channels with ocean water.

tides

Above: High tide fills the lagoon main channels with ocean water.

new-method

Above: This morning (June 25), crews began to reinstall the temporary berms using rock as they prepare the channel for installation of the 2B dike.

Crews have already completed sculpting the main channel sides in the Central Basin with excavators. They are now preparing for the Ross Island Dredge No. 10 to remove the material from the middle of the main channel (placed there by the excavators) and to remove additional material from the bottom of the channel.

The material removed by the dredge will be placed into the overdredge pit via the same types of pipes used to get the sand onto the beaches for replenishment this past spring.

Sculted Channels_Mudflat slopes

  • The left arrow points to sediments excavated from the sides of the channels and moved into the middle of the channel. The dredge will remove this material and place it in the overdredge pit in coming months.
  • The right arrow points to newly sculpted side channels for sloped mudflats.

From time to time, while crews are prepping and dredging the main channel, there will be a strong “lagoon smell”.  This emits from the disturbed high nutrient (decayed) sediments that currently exist in the lagoon channels. Temporarily restricted water flow may impact a loss in some fishes, though precautions are taken, these temporary impacts are expected according to project stakeholders’ expertise in designing the least impactful restoration plan. In coming seasons, we are going to see a lot of enhancements as we work efficiently to get in and get out.

Our vision is the flow of healthier waters, an increase in wildlife diversity, and new trail connections. It’s all worth the wait as San Elijo Lagoon will thrive even more when tidal flows reach deeper and farther into our treasured estuary. We are here to keep you informed every step of the way.

Have a question? Leave us a comment on this post. Your thoughts and questions can help us provide you with more information in Lagoon Connections

2 thoughts on “Deeper. Wider. And a High Tide, Too

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