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of each stream. Bridges eross tha streams at frequent Intervals In the urban areas. Tho channels have been altered by relocations and straIghtening in many locatIons throughout the urban reaches, The Van Blbber Creak channel Is conf I ne<J inastormsewer{underground conduit) for nearly 3,000 feet between KIpling St. and West 58th Ave. Beforeurbanlzation,LeydenCreekjc/nedRalstonCreeknearRensselaer Drive. Leyden Creek 15 now dIverted Into Ralston Creek nearly 7,000 feet upstream from the old confluence. In the upper rural reaches, the channels are sInuous. Channel dimensions vary widely frorn reach to reach. A narrow band of trees Is usually located along the streams. The tlood plains are nearly treeless and are used for farming and pasturage. The channels appear to have been straIghtened through some ot the farmed areas. Table 2 presents the general physical features ot the threestre.ams.whllethefollowlngphotographstyplfythestraam characteristics. GENERAL CONOITIONS This scctlon descrIbes the general characterIstIcs of the streams with emphasIs on the reaChes covered In this report. llALSTON. LEYDEN AND VAN RIBBER rJ1EEKS _ GROUP I StreamandYalleyCharacterlstics Ralston Creek is a mountain stream draining a 91-square mlleareanorthwestotOenver. Tho headwaters are In Gilpin County In the front range, As It emerges from the front range the creek continues eastward across the high plains and passes through Arvada before joining Clear Creek upstream of Sheridan Blvd. Tha dralmlge b~sl n Is 24 miles long and averages 4 miles In width. Slightly more than one-ha I f of the dra I nage area 1 s located 1 n the Rock ~Iounta i ns. Ralston Creek Reservoir Dam Is located across the creek In the foot- hlllsoostof the front range. The reservoir, operated bytheOenver Water Board, stores western slope water which Is brought through the MoflatTunnel. leyden and Yan 81bber Creeks ara ~jor trIbutaries to Ralston Creek. Leydan Creek drains an 11.5-s.quare mile 1lrea on the north sldo ot Ralston Creek. The Leyden Croek bllsln extends from tho foothills to SI","s Stroo-+. a distance of lI00'Jt 10",1105. Leyden lllk" Dam is locatedupstre1lmof Indlarkl St. atdbout the mId-point ofthebasln._ leydenLakeOamlSlllsoawaterstoragereservolr. Van Gibber Creek drains 11 17.5-S<"jw.re mIle "roM south of Ralston Creek. The headwaters are In the front range. From Its hOXldwaters. Yan Blbber Cre"k extends 14 miles eastward to Join Ralston Creek downstream of Garrison Street near the center ot Arvada. Only the plains portions of the stroams were studied In this report. The characteristics of the three streams are simIlar, The Channel slopes bocC<;1e flatter and the flood plains wider In the downstreamdlrectton. Urban I zatlon has begun inthelowerrp.aches Table 2 PHYSIC~L OIMENSIONS RALSTON, LEYOEN ~NO VAN BlaSER CREEKS Ralston Creek Length of Study ReaCh (Miles) Bed Slope (Fee+perMlle) NBIlrMouth Upstream End 01' Stuay R~ch Average Channel Depths (Feet) Minimum Ma><Imum Average Channel Top Width (Feet) Minimum Mi>ximum Aver"ge 11.0 25 105 50 2,0 12.0 6.0 t2 100 " , 5 Stream Leyden Creek VanBibber Creek 3.3 8.5 38 54 " 34 m 85 3,0 ),0 '.6 1.1 10.0 4.3 30 200 100 " '50 "