A federal judge yesterday upheld former President Clinton’s designation of six national monuments in Arizona, Colorado, Oregon, and Washington, dashing the hopes of the Denver-based Mountain States Legal Defense Fund. The conservative group challenged the constitutionality of the 1906 Antiquities Act, which gives the president the power to designate monuments, and argued that Clinton had exceeded his authority under the act. U.S. District Judge Paul Friedman in Washington, D.C., disagreed. The group said it would appeal the decision.