Mission Bay Water Levels: Record Highs Threaten Local Wildlife

Record water levels in Mission Bay submerged sandy beaches and flooded infrastructure in late October. The surge resulted from a rare alignment of natural and climatic factors.

Four distinct forces combined to push the bay to historic highs. The first was the annual king tide phenomenon. The second was Kelvin waves driven by El Niño. The third was unusually warm ocean temperatures. The fourth was long-term sea-level rise attributed to climate change. These factors worked together to displace water inland.

The high water reached its peak on Oct. 27 at 9:54 a.m. at Scripps Pier. The water sat 2.8 feet above the normal level. This measurement broke the all-time record set by scientists tracking the area for over 100 years. The surge extended from the bay into the Pacific Ocean. It erased most of the bay's sandy beaches. It also flooded bike paths and altered access for swimmers and paddleboarders.

Andrew Meyer, conservation director for the San Diego Bird Alliance, described the event as a preview of future conditions. He stated, "This is a visualization of what we're all concerned about. You can come see the future." The organization responded to the threat by conducting emergency work on nesting platforms. This work took place on Thursday to prepare for additional tidal events.

The higher water levels directly impacted the endangered light-footed Ridgway's rail. The bird's nesting platforms in Kendall-Frost Marsh became partly submerged. Meyer noted that the rails' feet were getting wet because the water exceeded the platforms' height. He said the organization had never faced this specific problem before. The marsh area consists of 50 acres of remaining land in Mission Bay Park. The Alliance maintains eight cameras and 21 nesting platforms there. One of the 22 platforms present in early October disappeared during the surge.

The National Oceanic and Atmospheric Administration predicts more king tides for Nov. 22 through 27 and Dec. 22 through 26. El Niño is expected to continue generating Kelvin waves through the late fall and winter. These waves move pulses of warm water eastward toward the coast. NOAA explains that these waves can temporarily raise sea levels by 6 to 12 inches or more. Warmer water also expands, causing thermal expansion that pushes water further inland.

Ocean temperatures in the region have hovered around record levels at 73 and 74 degrees Fahrenheit. These temperatures are at least 10 degrees higher than normal for this time of year. The heat is expected to remain elevated. The combination of warm water and high tides has shifted hunting grounds for local birds. Pelicans and double-crested cormorants were observed hunting in Kendall-Frost Marsh last week. These species typically hunt in the ocean or deeper bay waters.

City Council is scheduled to approve changes to its expanded marshland plan in mid-November. These changes were requested by the state Coastal Commission. Meyer said the marshes help combat sea-level rise by absorbing carbon and acting as sponges for coastal surges. He emphasized that the Ridgway's rail serves as an indicator of wetland health. He concluded by noting that some bird species may benefit from more open water, while others like the rail depend entirely on the marsh habitat.