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<br />or other materi..11s upon which a pipe or conduit is supported.
<br />Cbssific:ltions are: impermissible. ordimry, ordinary projection,
<br />first class, first class projection and concrete-cradle bedding.
<br />BEDROCK - Any solid rock underlying soil. sand. clay, silt,
<br />elc.
<br />BENTONITE - The plastic residue from the weathering of ash
<br />(volcanic). A soft. moisture absorbing rock, often of \'olcanic
<br />origin. co'.nposed of any of the montmorillonite-beidellite group
<br />of clay mmerals. Some bentonites swell on contact with water
<br />and are lIsed for sealing leaks in c3mls, tCscT\'oirs, etc., but they
<br />have no appreciable structural strength, hence must be used
<br />rngether with Concrete or soil to Support a large head of water.
<br />CAUCHE - A hard deposit, consisting mostly of calcium ("ar-
<br />bonate, found in the subsoil In arid sections, The deposit may
<br />range from several inches to se\'eral feet in thickness, and is
<br />presumed to ha\'e been created by minera]-Iaden capillary water
<br />c\'apomting and ]ea\'ing a residue which :ier\'cd as a cementing
<br />material.
<br />CAPA.CITY, I'vIOISTURE, FIELD - The a:rproximate quantity
<br />of water which Cdn be J'ermanent]y retaine in the ~il in op-
<br />position tu the downwar pulJ of gral'ity. It may be expressed in
<br />percent of dry weight or in inches de-Plh fN a gi\'en depth of
<br />soil. The length of time required for a soil to reach field
<br />moistu~e capacity \'aries considerab]~. ....'ith. various soils, being
<br />approxImately 2-+ to 48 hours for sandy sods, 5 to 10 days for
<br />silt clay soils, and longer for clays. A]so called cGJ.,ilIary capacity,
<br />field carr}'itlg Cf/pacit)', maximllm waler Iwlditlg cava-city. 1110iSf-
<br />Tire 1101dillg capacit.l, and Hormal moisture capllcity. See reten-
<br />timl, speCIfic; capaCIty, field.
<br />CAPACITY, \VELL - The maximum rate at whIch a \....ell will
<br />yield water under a stipulated set of conditic>os, such as a given
<br />drawdown, pump and motor or engine size. It may be ex-
<br />pressed in tenns of gal]ons per minute, cubic feet per second, or
<br />other similar units.
<br />CAPILLARITY - (I) The degree to which a material or ob-
<br />ject containing minute openings or paSS:1ges. when immer~ed in
<br />a liquid. will draw the s.urbce of the liquid aoove the hydrosta-
<br />tic le\'cl. Unless otherwise defined. the liquid is generally as-
<br />sumed to be water. (2) The phenomenon by which water is
<br />held in interstices alxwe the norma] hydrostatic le\'cl. due to at.
<br />traction of the molecules in the walls of an interstice for the
<br />molecules of the water and the attraction of the molecules of
<br />water for one another.
<br />COJ\.I1\HSSIONER, \VATER - (I) In western United States,
<br />a person Jj)pointed under statutory or court authority. whose
<br />duties im'o ve the administration of \vater rights or operations
<br />related thereto or connected therewith, such as supervising di-
<br />\.ers.ions of water from a streilm under a decree of adjudication,
<br />etc. (2) A Municipa] or district official responsible for the ad-
<br />ministration of a water supply system.
<br />COl\-IPACT, INTERSTATE - A compact between states.; some
<br />comp<lcts cover the development and IIti]ization of interstate
<br />streams, abatement of pollution, and other purposes.
<br />COURSE, SNO\\' - A line, laid out and pennanently marked,
<br />on a drain;lgc area aJc,ng which the snow is sampled at definite
<br />distances or stations, and al appropriate limes, to determine its
<br />depth, water cqul\.illent. and density, during a snow survey.
<br />CUBIC FOOT .PER SECOND - A unit of discharge for
<br />measurement of Howlng liquid, equal 10 a flow of I cubic fOG!
<br />per second rast a gi\.en section. Also called secolld.foot or eusee
<br />CYCLE, HYDROLOGIC - The circuit of water movement from
<br />the atmosphere to the e<:lIth and return to the atmosphere through
<br />\'Jrious stages or processes as precipitation, intercepticm. runoff.
<br />infiltrarion, percQlatlon, storage, evaporation and transpiration.
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<br />DAM. DETENTION - A dam whose ]?rincipal purpose is to
<br />temporarily detain all or l'art of the runoff and for release of the
<br />stored water at controlled rates through ungated outlets.
<br />DAM GROUND-\VATER - A geologic formation whic~ is im-
<br />pemle~ble or has a low penneability, and which occurs In such
<br />a position that it impedes the hOf1zontal movement of f!round
<br />water and consequently causes a pronounced difference m the
<br />levels of the water I3b]e on opposite sides of it.
<br />DEFICIENCY, MOISTURE, FIELD, The quanlilY of wale<
<br />which would be requned to restore the soil moisture content to
<br />fteld moisture capacity.
<br />DEMINERALIZATION - The removal from water of those
<br />di~solved mineral constituents which cause it to be unsatisfactory
<br />fo~ domestic or industria] uses.
<br />DEPLETION - (I) The continued with?rawal of. water from
<br />a ,.urface or gruund-water stream. re~er\'Olr, or baSin ~t a rate
<br />reater than the rate of replenishment. (2) In appralsa} work
<br />~e quantitative exhaustlon of ~atura] resources, usually In co~-
<br />nection with commerCIal exploitatIon and usually recorded In
<br />monetan. terms.
<br />DEPLETION. STR.EAM-FLO\V - The amount "f w~ler that
<br />flows into a \'alley, or onto a particular bnd area, .mmus the
<br />water that flows out of the v:.llley e,r off from the particular land
<br />area.
<br />DETENTION, SURFACE - That pMt of the r.ain which re-
<br />mains on the ground surface during rain and either rum. oH, or
<br />infiltrates after the rain ends; surface detention does not .Jnclude
<br />aepressiotl storage. The detention depth increases until dIscharge
<br />reaches equilibrium with rate of supply to surface rUllOff.
<br />DISTRICT, DRAINAGE - (1) An organization, creatc~ and
<br />operating under stiltutory enactment, fur the purpuse of fmanc-
<br />ing, constructing, and/or operatin~ a drainage .system. .C2? The
<br />land or :.Hea within the boundanes of a drall1age dIstrict. as
<br />delimited in the org<1nic statute.
<br />DISTRICT, IRRIGATION - (I) An organization. create? and
<br />oper<1ting under statutory enactment. for th~ p~rpuse of financ-
<br />ing, constructing, and/or operating .an Imgatl.o~ s~stem.. (~)
<br />The land or area within the boundanes of an Irrigation dlstnct
<br />as delimited by the organic statute.
<br />DISTRICT. SE\VER - (I) An organization. created. Jnd .op.
<br />erating under stJtutor)' enactment, for the purpose ~o~ fmancmg.
<br />construcrmg. ;:md/ur opCnlt!ng a sewerage ~y:;t.elll. (..2) Th.e Ja~d
<br />or area within the ooundafJes of a sewer dlsrnct. as dehmlled In
<br />the organic law. It may embrace parts of one en more polllieal
<br />subdivisions.
<br />DISTRICT, \VATER - (I) An org:mi1..ation created dn.J up~rdt-
<br />Ino under StJtut0ry enactment, for the purpose of finanCing,
<br />co~structing, an? (~~r operating a ~...'ater supply ~yst~m.. (2) The
<br />bnd or area \\'lth1l1 the boundafJes of a water dlstflct, as de.
<br />limited in the org<lnic statute. It m<1Y embrace p;Jrts of one or
<br />more poliric:.d subdil'isiolls.
<br />DITCH - An artifIcial open channel or waterw.l\' constructed
<br />through earth or rock, for the (>urpose of carrying water. A dllch
<br />is smaller than a c<lnal, ;ilrhough the line of demarc;1tir,n between
<br />the [wo is indefinite. A ditch usuall" has sharper cur\'ature in
<br />its alinement, i~ not c.omtructed to such H..finement of unifonn-
<br />ity of grade or cross section, and is seldom lined with impervi-
<br />ous rnJterial to prevent see[Jage.
<br />DIV1DE, GROUND~\VATER A lint' on il WJter table on
<br />either side of which the \-....:iter table slopes dtlwnwJrd. It i~
<br />analogous to a drainage diVIde between two drainage basins on a
<br />land surface. The buundary of the cone of pumping depression.
<br />DRAIN AGE - C I) A general term applied \0 the removal of
<br />surface or ground WJter from a given <1rea either by gra\'ity or
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