Several dozen environmental groups will send a letter to Pres. Clinton today expressing “deep disappointment” over administration policy on Northwest forests. The enviros believe the administration’s Northwest Forest Plan, put in place in 1993, provides far too little protection for old growth. The timber industry, for its part, maintains that the plan is unworkable because it doesn’t allow enough timber to go to mill. Agriculture Secretary Dan Glickman was in Seattle yesterday trying to convince parties that the plan is proving successful, the first such statement from a high-ranking administration official since a federal judge halted dozens of timber sales in the Northwest last month, claiming that the feds had violated the Northwest Forest Plan.