WSP08349

• File Number: 8407
• Description: Platte River Basin - River Basin General Publications
• State: CO
• Basin: South Platte
• Water Division: 1
• Date: 12/6/1995
• Author: USGS
• Title: Quantity and Quality of Ground-Water Discharge to the South Platte River - Denver to Ft Lupton - Colorado - August 1992 through July 1993
• Water Supply Pro - Doc Type: Report/Study

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-.- McKay Road

-e- Henderson

-,A.- Road 8
Road 81N1B Line indicates average
concentration of total
organic carbon in
ground water, name
refers to wells in table 3

10

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8

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McKay Road ..
1A/1B

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Road 8 1A11 B

Henderson 1A11B

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60

80

100

DEPTH BELOW SEDIMENTIWATER INTERFACE, INCHES

Figure 16. Concsntratlons of total organic carbon In ground water with dspth below the sedlmsnllwatsr Interfacs
at McKay Road, Hendsrson, and Road 8, Samplss at McKay Road, Hsnderson, and Road 8 were collscted on
October 1, 1992; October 5, 1992; and Ssptembsr 25, 1992, respsotlvsly. Valuss for surface water Indicated at a
depth of 0 Inchss below the sedlmsnllwater Intsrface.

Concentrations of dissolved nitrite plus nitrate,
ammonium, and phosphorus in water samples from the
piezometers at the 30 cross-section sites ranged from
less than 0.01 to 8.98 mgIL as nitrogen, less than 0.1 to
15.3 mgIL as nitrogen, and 0.28 to 7.22 mgIL as phos-
phorus (table 9). The median concentrations of dis-
solved nitrite plus nitrate, ammonium, and phosphorus
were 1.22 mgIL as nitrogen, 1.7 mgIL as nitrogen, and
1,41 mgIL as phosphorus. Concentrations of nitrite
plus nitrate in ground water below the sediment/water
interface increased with distance downstream from the
MWRD plant, whereas concentrations of ammonium
decreased (fig. 17). Concentrations of phosphorus
showed no consistent pattern of change with distance
downstream from the MWRD plant. The pattern of

concentration changes observed for nitrite plus nitrate
and ammonium with distance downstream from the
MWRD plant is similar to what has been observed in the
river. The pattern of concentration changes in the river
is generally attributed to the addition of ammonium to
the river from the MWRD plant, followed by the conver-
sion of ammonium to nitrate by nitrifying bacteria as the
water flows downstream. Due to the movement of sur-
face water into and out of the bed sediments, it is likely
that at least part of the concentration pattern of nitrite
plus nitrate and ammonium observed in the small-area
flow system (fig, 17) is the result of similar processes.
However, other processes also were active in the small-
area flow system.

30 Quantity and Quality of Ground-Water Dlscharga to tha South Platte River, Danver to Fort Lupton, Colorado,
August 1992 Through July 1993