Boca Raton Officials Evaluating Fish Die-Off in Lake Near Library

Dead fish dotted the banks of the lake near the Spanish River Library in Boca Raton on Monday, prompting a response from officials aimed at figuring out the cause and determining a way to restore the lake’s health.

Known formally as “Blue Lake,” the body of water is located to the north of the library off Spanish River Boulevard and features a popular walking trail and scenic viewpoints. The fish appeared to be, generally, around 8 to 12 inches in size and were primarily silver in coloration. The species was not identified by officials.

Fish washed up on the side of the Spanish River Library (Blue) Lake, Boca Raton, FL, Feb. 9, 2026. (Photo: Boca Daily News)

“We have been made aware of the current conditions at the Spanish River Library’s Lake,” Boca Raton’s Recreation Department posted to social media. “The city’s Public Works and Engineering teams are on-site, working with specialized contractors to assess the water and provide necessary treatments.”

According to official sources, the lake contains largemouth bass and butterfly peacock bass as its primary species, plus a variety of others, including bluegill and sunfish. A few people could be seen fishing there Monday night around sunset.

Fish washed up on the side of the Spanish River Library (Blue) Lake, Boca Raton, FL, Feb. 9, 2026. (Photo: Boca Daily News)

Fish washed up on the side of the Spanish River Library (Blue) Lake, Boca Raton, FL, Feb. 9, 2026. (Photo: Boca Daily News)

Fish washed up on the side of the Spanish River Library (Blue) Lake, Boca Raton, FL, Feb. 9, 2026. (Photo: Boca Daily News)

Fish washed up on the side of the Spanish River Library (Blue) Lake, Boca Raton, FL, Feb. 9, 2026. (Photo: Boca Daily News)

Archival news reports do not indicate any fish die-offs at Blue Lake before, however a 2021 incident was widely reported at Sabal Lake off W. Yamato Road. In that instance, officials ultimately determined the discovery of dead fish was linked to low dissolved oxygen levels after a drought. Anecdotally, some reports indicated fish kills can occur after oxygen levels fluctuate following drastic changes in temperatures, which the area has experienced in recent weeks.