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,10i18 /1 DRAFT FINAL DRAFT - 1:!/20l9t Streamflow is lowest during me wimer and C.lrly spring. It begins to increase due to snow melt runoff sometime between the end of ~Iarch and the middle of ~1ay. The higher flo.....s associated with snow melt persist for one and a half to two and a half months and there are typically several peaks during this period. See Figure C. This is due to combinations of one or more factors. such as precipitation events, shan-term changes in temperature, or the individual characteristics of the suh-watersheds. such as slope. aspect. and elevation. There Me aLsu 100t~ summer ;md lall p~k5 ~su..:jat..:J \101m fronul .illl.1lhunJer ~tufms. Allhuubh tho: IT!.1:;::nit1ldl" nflh~"e ]~I" ~l":~<:"" ["t':A<: v",ri,..:. ;,nd j" "<:IJ311~'lm~-'..~ lh",n Ih..",.. "(;<;P:;'I~,i \\;I!, snow mdt. the)' do occur every year. AnnualllydrOltf".pb .1938 Pitdr. Riv~ .t UpfM"f" lAild~~ Boundary Sum orPit"dra Riv~. Wrlllinu(ht and \\illi.m.~ Crr-t"-' :: I '''''' 3' I ~ 12w ~ ~ I j 1~)] r f ~! , ~ '" - ~ - s. - ~ - ~ ~ % - " " ;; ;;; ;;; ;;; ;;; '" ~ ~ ~ ~ ~ ~ ~ ~ ~ - ~ ~ - S:;-~::7S~S%~~~~ Figure C A typical riparian site along the river corridor contains mountain alder, red-osier, several species of willow, and horsetail. Coyote and Bebb are the most common species of willow. The narrow valley bottom and steep canyon sideslopes prevent the riparian vegetation from occurring too far from the stream channel edges. Therefore, the riparian lone is typically lhree to ten feet wide. Alder, red"sier, and willow occupy a broad band adjacent to the active channel. lndividual uees and small stands of narrowleaf cottonwood are scattered along the mainstem of the Piedra and along the uibutaries near the mainstem; most are located on low terraces. Cottonwood is not considered a major component of the plant community at these sites, Riparian species, especially willow, will colonize deposition areas behind debris dams and gravel bars. Although the location of these areas will shift over a several year period, their acreage within the wilderness is probably relatively constant. There are two sites within the wilderness near the upper boundary where narrowleaf cottonwood is a major component of the plant community. At these sites, the valley bottom is wider and has both floodplains and low terraces which are occupied by cottonwood. Page 6