Treeview Node and querystring variable

Hi,

I have a treeview node (.net 2.0) that has a NavigateUrl="~/Project.aspx" . How do I say that I want to append a querystring variable of a public variable from the code behind named lang?

I thought it would be something like NavigateUrl='~/Project.aspx?<%#strLang%>' but this doesn't work.

Thanks

<asp:TreeView ID="infTreeView" runat="server"
                        ImageSet="Simple">
                        <ParentNodeStyle Font-Bold="False" />
                        <HoverNodeStyle Font-Underline="True" ForeColor="#5D7B9D" />
                        <SelectedNodeStyle Font-Underline="True" ForeColor="#5555DD" HorizontalPadding="0px"
                            VerticalPadding="0px" />
                        <NodeStyle Font-Names="Tahoma" Font-Size="10pt" ForeColor="Black" HorizontalPadding="0px"
                           cssclass="BellowMenuBanner" NodeSpacing="0px" VerticalPadding="0px" />
                        <Nodes>
                                                 <asp:TreeNode NavigateUrl="~/Project.aspx" Text="Project" Value="Project" >    </asp:TreeNode>
                            <asp:TreeNode NavigateUrl="~/Reports/Reports.aspx" Text="Reports" Value="Reports"></asp:TreeNode>
                            <asp:TreeNode NavigateUrl="~/Maintenance/UserMaintenance.aspx" Text="User Maintenance" Value="User Maintenance"></asp:TreeNode>
                        </Nodes>
                    </asp:TreeView>