The invention relates to novel wellbore treatment methods and fluids using compositions formed from an aqueous medium, a regularly substituted hydrophilically functional polysaccharide having a degree of substitution from about 0.1 to about 0.5, wherein the percent of insoluble polysaccharide is about 10% or less, and a crosslinker. The wellbore treatment fluid is particularly useful for fracturing a subterranean formation penetrated by a wellbore.