NonBasicSpecificComments05

• Title: Comments 5
• Date: 10/23/2003
• SWSI - Doc Type: Comments

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, 38 J4 S. Covjogton ana W. A4 Hubel1

Tbt' cU,nate of the Salt River watershed is classified
as cold ,vim humid wintcrs... Me3l'1 anl1ual air tell1pcra-
LUre on tbe 1IiLUey flool" is a.'so.c (Owenby ~nd EmU
'9g2)~ Ann1Jal pte-cipicatiotl averages' 50 cnl Gn the
vaney flOCH. 3nd exceed.s JOO em at high elcYa4:ions
(O~thberg 1 ~S4). l-lfdrograp hs of m ounrain cribu ranes
al"e domin3[eQ by .$nowrnr:lr. \vitII peak d,~harge~ in
May andJune, followed by base flO'V5 from I.atejuJy into
March (US Geologfeal Su",ey~ unpublb;hed dam)<1 Ri..
padai'l vegel3.uon adjal:en t r.o streams. on th ~ valley
noor c;onsisr.s of wjUows (Salix spp.), cOltonwr,)ods
(poJml-us spp_), se=dges tem'ex spp.), and. gl"'3St~5"
N~1tive :ipo.~t flsh~~ in th~ SaIl Rlvl!r ~'atershed ,are
cutth roal trout (OnttJrl&J."cntl.f. Clarki) I and m.oUt1tain
,...h i tt;fi r;b (.ProstJpi'Um tuUliatlu01J.z.). BrowtJ trOUt (Salmo
&tuUa), rainbow trOUt (Oncttrh.yn.chlU i'n)/Cr.sS) '\ and b,"O(.)k
trout {Salvcli:nus ftm.tiMli..~} . have been introd.u~ed.
.Brown ,rout ar-e na(uraliz~d \\rithin the Inain stelll Q[the
Sal L River, Ule dO\;ftutn:am segments of tl'ib~tal"i~.s: flow-
ing across the vaUey floor. an.d spring strr;ams (Isaak
I .2001) ~ Brook ~roUr are self-perpetuating in some spring
Strean1S and niJ,u L:lri r:S l\'i tJ J in un: IIJUl1 [n.ai I $5. Rai 1'1 bow
trout are present in the downsLrealn portions oftl:ie Sa1[
rover and some adj~ccnL spring s~reruns (Isaak 2001).
Lan d use is f\Jinc~ pally agricul cure on private land
across rhe valley floo~t; (Ravenholt and O(JH~rs 1976) willI
aJfalfa and b(u.ley as me principal crops. Cattle and
sheep al'e gr<12:.ecl throughout the valley. Mounwllous
area.1i: a ~ P\1 bli ~\y n\\I'nc:rl an d. nl2.1l;1ged by the t;s F Ort;st
Service primarily for livcstock. gra2ing and recreation~
Stream hydrologic rcgimc:s are altered wh~re- [I.ibumr-
ies from mountain :areas enter the sIlI.n.rial v:aJleY4 Nu-
~merous 1vater diversion $tl1.\CtUI"CS shunt Stream Ilows
for irJigadon during the agrlculturaJ growing season~
Small storage reser\.oirs l1iLve been constructed 011 ~o
mQutnain bibutarir:s. further affecting Ao\vs. Conse-
quentJy, the hydrology (If dO~\Irn1tream potlions or trib-
umrics and a portion of tbe Sail: River is highly altered
duri ng the growing se3$OIl witll less. than natural base
fl OW!. Several streatl1 segmC:ll ts are totally dewate rt:d.
during ponions of 'the summer.
Although most of the \--alley flool" is used for agricul-
ture, there is considcl"3ble residen[ial developnlel'1t.
COULilllJ.~c.1 subdivisioll ofagncultu.r:a.\ land into rcsiden"
tiaJ property iJ expected itl the futl1re. With increasing
J."esideri[iaJ development. a dichotomy is developing ~.,
tlvecn lo.ng.term residents and ~ceI1[ hiuui!$'Jif.J1Li uvc:r
uses of water- Loflg-term residents generally prefer me
econolnic benefits or inipdon fo.r agrlr.ultural p roduc:...
don, whereas many new residcllt$ pefl:eive bCnefi[!
froQ] frec..no,,,ing streamSL pal-dculady their potential
to support sporr. Fisheries.. T~ere is a need to waigh the

19JOO~

2

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henefits of water for irri~tion to instte'alll flaws (0'-
fisheries \\'1thin ~he valley.

AppUcation

Stream Segments

We applied OUl. appl~ach [0 segrncal[S. of fi\:e f.l~ibu-
UlriC! (Stra,,;herry, St\.\ll~p.. Swiftl Dry, and Cotlon\Vood
r:reck~) and the upper Salt Rivet that a....t:' lOlaU;~ dewa",
tered annually during the i.Tig-.adon seasOIl (FigLu'e 2)~
Scgn1CDtS were idcntifiA:d as the Jength~ of stre~nl \'iith
homogeneolls Ro\IJS hetyteen the upstrealn WAter divel"-'
sian .sU"lIct1..lre and where ,t Jncrge... with alfothe.& strearn.
!Jl 1iix atream ~ segments had lol't" channel s~opes
!<lt5%) and he:gan nc:a.. the point wher~ the 5tJ.~eatns
.e.nerged froln the moun tains and llowed across the
aU uvial vane" floQr.. There were no '\vater diversio.l.l
strUC:UJfCS O'1ler [he leLlgch of each ,$egment We nsked
[\111.,) questions: Wha~ ,.I(ouJd be th<: taral biornass and
a.bt.lndance of t.tOL1t over each .segment if che nn.tl~}Utl]
hydrology were restored rhro\1ghout each ~e"ment?
\Vhat wou.ld be tho bionlass an ('1 abulldance of trOllt
over ~aC'b .5~gmcllt if:spccifi.e flQ1flI'S. less than the L-.aatul'al
average summer b~~ no,...s ~vere esrablished th rough-
OU~ cae}l segment? The lOllgjtlldina' varlation ill. phys.-
ical habitat ft=~U:llrC.5 OVCt the loud \engdl of each seg-
ment and rlle length of eal;h segmenl Were considert:d
wh.en ans''Iering these qtLCstion5~

stream ReacHes

Stream se~nencs were divided ~nto rc:aches t\ritll ho-
mogeneous riparmn vegC:Cldoll and b"'-Ill:. ff;,,"Lu~~ using
aerial photographs that ''''ere 0:-9 years old. Acria1 pho.
eographs (1:40,000 scale. color infrared) had been
taken from JU1, to Sept.elnbcr as pArt uf \I~~ N:illiorul\
Aelial Photogr-'lph Progrnln and w"erc obtainl:d from
thl! US Geological Survey ARROS Spatial Dala. Cellle'-
(Ltght 1996)~ A bino~ulaT mtc:roscope (7-S0X I'u:a.goi..
. ficadoo) was used l.O view thCS' images..:Change.s .in ritl;ilr-
Ian and bank features were generaUy associaled with
boundaries created by fences and (oat.! CtO!iSh1g~.
Wht:TC evident ebanges occurred. J:letN reaches were
noted. Where long rc;'ac.he5 of hOltlogeneol..ts riparian .
f~a[UI.es occurred, reacbes wert: dividt.:tl :so Lhat ma~l-
tnum, length was less than 400 111.. Mean i-each. 1c1'l~th
was 905 m (range 64-386 m).
Estimates of ['u;"ee ph)SiciJl habiUtt fealure'S wen;
matte within each r~~c.h4 Elevation and channe.l slope
were eSlhuatcd L1sing 7.S.roio USGS topographic maps.
Elevat:lon was dClermined at the rnfdpOJUL of each
r~ach. Channel slope was cOl~'puted using estjmat~~ of'
cleV3tio~'" i[ each el'td ol~ a reacl~ and the Icngtl) of'the

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