Video of the incident, which has caused outrage online, shows a Color Me Mine employee using a bucket to dispose a green-colored liquid.
The business released a statement that said the paint solution dumped was non-toxic but acknowledged that that employee was in the wrong.
"Santa Monica is a city that prides itself on its lovely beaches and having been a part of the community for many years, we are ashamed that such a huge mistake was caused by one our own," the business said in a statement. "These actions caught on video not only are not standard procedure but also the first time in 15 years of ownership this has happened."
The Santa Monica shop issued an apology and said the worker was reprimanded. The business is working with the city on any clean-up costs.