Overflow/Overflow.Web/Components/Layout/NavMenu.razor

@rendermode InteractiveServer

<RadzenMenu Click="OnParentClicked">
    <RadzenMenuItem Text="Home" Icon="home" Path="/">
    </RadzenMenuItem>
    <RadzenMenuItem Text="Southern Water" Icon="water_drop">
        <RadzenMenuItem Text="Spills Data" Path="/spills" Icon="table_view"></RadzenMenuItem>
        <RadzenMenuItem Text="Spill Events" Path="/spills-cal" Icon="event"></RadzenMenuItem>
    </RadzenMenuItem>
</RadzenMenu>

@code {

    void OnParentClicked(MenuItemEventArgs args)
    {

    }

    void OnChildClicked(MenuItemEventArgs args)
    {

    }
}