Water diversions have historically been considered the major factor decreasing salmon and steelhead populations. Before the construction of New Melones Dam, the river frequently ran dry starting in early summer, especially in drought years, due to farmers taking all the water. This prevented spring-run smolt from making their way down to the sea. The little water left was usually too warm for the fish to survive. In 1992, federal dam operators began releasing large volumes of water or "pulse flows" into the Stanislaus River during the critical spring and fall spawning seasons hoping to replicate natural conditions of snowmelt and autumn storms, respectively, in order to help the fish reproduce. Between 2000 and 2009, about 55 percent of the Stanislaus River unimpaired flow was released from Goodwin Dam into the lower river, far more than the historical average of 39 percent. This is also considerably more than flows released into the nearby Tuolumne and Merced Rivers, which are also historical salmon and steelhead habitat. In fall 2015 higher flows on the Stanislaus River led to more than 11,000 chinook returning to the river, as compared to less than 1,000 fish in the Tuolumne and Merced.