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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 Stream and Valley CharacterIstics 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 contlnuas eastward across the high plains and passes through Arvada before joining Clear Creek upstream of Sheridan Blvd. The dralmlge b~sl n Is 24 ml las long and averages 4 miles In width. Slightly more than ona-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 by the Denver Water Board, stores western slope water which Is brought through the MoflatTunnel. leyden and Vlln Blbber Creeks are ~jor trIbutaries to Ralston Creek. Leydan Creek drains an 11.5-s.quare mile area on the north side ot Ralston Creek. The Leyden Crock bllsln extends from tho foothills to SI","s Stroo-t, a distance of lI00'Jt 10",1105. Leyden LlIk" Dam is located upstream of IndI1lrklSt.1Itdboutthemld-polnt ofthebasln._ Leyden Lake01lm Is 1I1soa water storage reservoir. Van Gibber Creek drelns 11 17.5-S<"jw.re mIle "roM south of Ralston Creek. The headwaters are In the front range. From Its hOXldwllters, Van Blbber Creek extends 14 miles Bastward to Join Ralston Creek downstream of Garrison Street near the center ot Arvada. Only the plains portions of the stroams were studied In thisraport. The characterlst1cs of the three stre1lmsare slm/lar. The Channel slopes bocC<l1e flatter and the flood plains wider In the dow"streamdlrectton. Urban I zatlon has begun inthelowerrp.aches Tabla 2 PHYSIC~L DIMENSIONS RALSTON, LEYOEN AND VAN BlaSER CREEKS Ralston Creek Length of Study ReaCh (Miles) Bed Slope (Fee+perMlle) NBIlrMouth Upstream End ot Stuay R~ch Average Channel Depths (Feet) Minimum Ma><lmum Average Channel Top Width (Feet) Minimum Maximum Aver"ge 11.0 25 105 50 2,0 12.0 6.0 12 100 " , , Stream Leyden Creek VanBibber Creek 3.3 8,' 38 54 " 34 m 85 3.0 ),0 <,6 I,) 10.0 4.3 30 200 100 " 150 "