FLOOD08469

• County: Denver
• County: Jefferson
• County: Adams
• Community: Denver, Jefferson County
• Stream Name: South Platte River and tributaries
• Basin: South Platte
• Title: Major Drainageway Planning South Platte Phase B, Volume I
• Date: 11/1/1985
• Prepared For: Denver
• Prepared By: Wright Water Engineers, Inc.
• Floodplain - Doc Type: Floodplain Report/Masterplan

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bank for the full river length fr()1l Sand Creek to Briahton, the alluvial
groundwater extends eastward for, in some places, as moch as 7 miles.
Through the City of Denver, from Sand CreektoBlg Dry Creek in Englewood,
the depth to water table adjacent to the river is from 10 to 20 feet. From
Big Dry Creek to Chatfield Reservoir the water table is again shallow,
ranging from 10 feet to less than 5 feet.

These three reservoirs "ere built and are operated by the U.S. Amy Corps
of Engineers. For each of the reservoirs, releases are controlled by
federal andstatepersol'fnel.

There is a need for an adequate base flow;n the South Platte River to
accOImlodateseveral needsandactivlties, including;

Chemical ~ater Quality
The chemical qual ity of grou~d'Hter as measured by dissolved sol Ids CO!lcen~
traticms is less than 51)0 mg/l f~OOI Chatfield Reser~oir clown to Columbine
Valley. From C01 LJllbi~e Vall ey to Brighton the groundwater in the all uvium
Of th~ S~lJth Platt" River h~s ~ dlssolv!'d ~,.,licl~ r.onc~ntrdtion in ~xce~> of

o D11utlonof sewage effluent to reduce the deleterious impact of
sewage effluent flow through the heart of Denver a~d Adams County.
o Dilution of polluted drainage wdter dischdrged frommHropo11tan
storm 5e~ers and gulches.
o Provision of minirnlJll f1ol<ls to carry off p~troleurn products such as
gasol ine (from vehicu1 ar accident ~He f1usllinq) a~d oil ~hich
find their WdY to tlle river.
o Provi5ion of f1o~s to support tlle aquatic 1 ife whiCh exists in the
river for its full 1 ength, r dng i ng from tro~t in L Ht leton, cat~
fiSh in Denver, to fish and bottO'll<living crustilceans downstream

Evaluation of depth to ~dter tdble indicatl's th~t river cllaMellzatlon, and
confining of the river ~Hhin narrow fixed banks, resu1ts in lower water
tables due to the f~t thilt the d€ep channel S€rVeS as a deeper groundwater
dr~in. A deeper river channel mean~ lowered \'later tables.

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cf Sand Creek.
Adequate f10W5 to support rafting. kayaking, cMoelng, and ~peci~l
boating events, which dr~w a5 many as 100 boaters and in exces~ of
1,OOOspectator/participantspereventincentral Denver.
Swimminq. though it is not sponsored. or supervised.
occurs mostly among inner-cHy youth, primarily at the
of the South Platte River with Cherry Creek.

Swir!'ll1ing
confluence

500ms/l.

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We" YieldS
Well yields from the South Platte alluvi~l ~quifer are satisfactory for the
ent i re 40 mile ~tudy r"ach. lnd iv id ual pumpi ng rates of from 500 to t,OOO
gpm are COrlvnon. There are least 15 zones where the ~el1 yields range be-
tween 1,OOOdnd 1,500gpm, with some wells P\lllpin'l in excess of 1,500gpm.

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RIVER FLOW AND RESERVOIRS
Thf' South Pl~tte River from Chatfield to Brighton is a <nostly controlled
river, though for flood purposes the effect of the flood control reservoirs
is significantly diminished belo\'lthe Cherry Creek confluence . The flow of
the river i 5 controll",d by rel"a~,,~ from Chatfield Reservoir, Bf'ar Creek
Rf'~f'rvoir, and Chf'rry Creek Reservoir. \;hich are referred to as the Tri_
Lakes.

A reasonably adequate <ninima1 b~se flo~ for boating purposes \'IOuld range
frQll1 100 cubic fel't per second (cfs) in Littleton to 200 to 300cfs at the
Speer Boulevdrd bridge, just upstream from the Denver g<llJing station.
Speer80ulevardisattheentrancetotheConfluenceParkWhitewaterSlalom
:!o~t Chute. The maximWl safe flow for qeneral publiC boating is aMut
1,500 cfs aSn1€asured at tM Littleton gag"'. A.t flows above 1,500cfs
boating should be limited to experienced oeople.