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<br />Reach 6A <br />Reach6B <br />Reach6C <br />Reach 60 <br /> <br />McClellands from Timberline Road to Union PaCific Railroad. <br />McClellands from Union Pacific Railroad to Harmony Road. <br />McClellands from Harmony Road to center Section 35. <br />McClellands from center of Section 35 to upstream study <br />limits. <br /> <br />Reach 3, the New Mercer Canal, is one link between historic McClellands and <br />Mail Creek. The Canal has recently been relocated and the Channel section enlarged. <br />Storm flows from Reaches 4 and 5 are now discharged directly into the canal. A <br />54-inch diameter RCP conveys irrigation and storm flows under the C & S Railroad <br />and Harmony Road into Mail Creek. The maximum irrigation flow possible in the <br />ditch is125cfs, but the average irrigation flow is estimated to be 80cfs. For <br />analysis purposes, 80 cfs was assumed to be flowing in the canal during all storm <br />events. <br /> <br />Reach 1 of Mail Creek is a well-defined channel with steep, sometimes verM <br />tical banks, and an abundance of vegetation. It isa natural section in generally <br />good condition. The Channel section in Reach lA Is 30 to 5Q feet wide at the bot- <br />tom with an 8-foot to 20-foot wide low flow channel which meanders across it. The <br />channel is 10-feet deep and contains native grasses, willows, and occasional <br />cottonwood trees. The overbanks are cultivated for a1phalfa and hay. The channel <br />section in Reach 1B is similar to that in ReaCh lA except that two (2) culverts <br />have been placed in the stream and the overbank areas are now residential rather <br />than agricultural. Upstream from Passway Drive, the channel is steep with l5-foot <br />banks which show evidence of sloughing in some areas. <br />A small dam has been placed across the Mail Creek channel at Palmer Drive, <br />ReachlC. and a reservoir has formed behind it for a private lake. Furtherup- <br />stream, another dam has been constructed forming another small 1 ake. However, the <br />purpose of the structure is for the inlet works for the Mail Creek irrigation <br />ditch. At the upstream end of this second lake, the Larimer County Canal No.2 <br />waste ditch discharges excess irrigation flows into Mail Creek. <br />Likewise, in Reach 10, irrigation water flows into Mail Creek from the New <br />Mercer Canal at a point just downstream from the C & S Railroad. The Channel <br />section in this reach is in a natural condition with heavy growths of vegetation <br />which are fed by the constant flow of irrigation water. <br />Reach 2A, for example, does carry a small trickle flow, but is more open <br />and flatter than the lower reaches. The channel runs parallel to Harmony Road <br />~~d has ~een o~literJted to no ~ore than swales ~y the shoulder of the rood west <br />of Crest Road. The small triCkle flow originates from irrigation runoff and <br />domestic sources, since many contributing subbasins have recently been developed. <br />Culverts have been placed in the channel at several locations, but are all too <br />srnalltocarrysignificantrunoff. In one location, small dams have been conM <br />structed in part of the channel on private property for landscaping purposes, and <br />these represent a potential flood threat to that individual property. <br />Reach 28 upstream from Shields Street contains no well-defined drainage <br />channel. It is more a swalewhichis cultivated. About 1,OOOMfeet west of Shields <br />the Pleasant ~al1ey and Loke Canal intcrscct~ thc drainagcway ond inte~ccpts run- <br />off originating above it. <br />Reach 1 and 2 constitute historic Mail Creek. Runoff in Mail Creek now <br />includes storm flows from the McClellands Basin west of the Larimer Canal No.2 <br />waste ditch because manmade features including College Avenue and the New Mercer <br />Canal,cutoffthenaturaldrainagewayandredirectstormflowstothesQuth. <br />Because of this, the Mail Creek Basin now envelopes all of the historic McClellands <br />Basin west of the Larimer County Canal No.2 and therefore three (3) additional <br />reaches are included in the Mail Creek Basin study area. <br /> <br />Reaches 4 and 5 extend along the historic McClellands drainageway from the <br />New Mercer Canal to the upstream study limits west of Shields Street. The basin <br />topography is relatively flat and historic land use is primarilyag ricultural. <br />The channel is shallow and wide, and is now flanked ~y new residential areas in <br />ReaCh 4. In Reach 4A, the Channel has been replaced with a 24-inch diameter RCP <br />storm sewer. <br /> <br />Upstream from Shields Street, Reach 5, there is no well-defined drainage <br />channel and the floodplain area is cultivated. The Pleasant Valley and Lake Canal <br />intersects the drainage near the upper study limit and storm runoff from areas <br />above the canal are intercepted and transported out of the basin toward Fossi] <br />Creek. <br /> <br />McCLELLANOSTUDYREACHES <br /> <br />Study Reach 6 begins at Timberline Road and extends 2.3 miles upstr earn to <br />the present McClellands Basin 80undary. Reach SA and 68, which are south of Har- <br />mony Road, traverse agricultural landS and are fairly shallow and wide ....Because <br />of the flatness of the terrain, a large pool can develop behind the railroad em- <br />bankment and downstream areas. <br /> <br />Reaches 6C and 60, w~ich are nortn of Harmony Road, have b~en develooed into <br />a series of detention ponds interconnected with open channels and a nunderground <br />storm sewer. Most of the baSin within these reaches has been urbanized except for <br />a small area just west of the center of Section 36. <br /> <br />11-3 <br /> <br />11-4 <br />