If there is a code violation (e.g. a violation of local muncipal health or building code, or any code specifically relating to pools), then you could report the violation to the appropriate municipal department. But in the absence of a code violation, there really is nothing you can do other than bring the issue to your employer's attention: apart from when a health, etc. code (which are typically local) is violated, the law does not specifically give employees a right to a hygienic workplace. You can contact your municipal health department to see if there may be some violation, though best would be to first tell you employer and see if they address the issue.