Stage 1 Report
First Quarterly Progress Report
Final Report Page 3 October 2004
It should be noted that the listing, while warranted, is based on only three dissolved
oxygen measurements, with two of the three measurements being approximately 2
mg/l below the criteria of 5 mg/l. Causes of low dissolved oxygen typically include
sediment oxygen demand, degradation of CBOD, nitrification of ammonia and/or
algal respiration. Although there were insufficient data to assess the relationship
between ammonia and dissolved oxygen, SOD and DO, CBOD and DO, and
chlorophyll and DO, potential sources in this watershed were identified through the
watershed characterization. These sources may include runoff from agricultural land
(fertilized cropland and agricultural land with livestock) and failing private sewage
disposal systems (lesser extent). There are no point sources in this watershed.
Similar to what was observed farther downstream of this segment, low flows and high
temperatures may also exacerbate low dissolved oxygen concentrations in this
segment.
• For Horse Creek (Segment CAN 01), data are considered sufficient to support the
listing of this segment for dissolved oxygen; however, the data were extremely
limited. Only two of the four measurements were below the DO criterion. The data
are also sufficient to support the listing of this segment for manganese with one of
five samples exceeding the general use criteria for manganese. Causes of low
dissolved oxygen typically include sediment oxygen demand, degradation of CBOD,
nitrification of ammonia and/or algal respiration. Potential sources contributing to
one or more of these causes include failing private sewage disposal systems (lesser
extent), runoff from agricultural land (fertilized cropland and agricultural land with
livestock), a permitted point source discharger, and an intensive animal feeding
operation. The observed manganese concentrations likely reflect natural background
conditions (soils in the watershed are naturally high in manganese), although brine
from oil wells may also contribute to the elevated concentrations. Because of the
naturally high levels of manganese in the soils, the general use criterion may be
difficult to attain.
• For Brush Creek (Segment CAR 01), the data, though extremely limited, are
considered sufficient to support the listing of this segment for dissolved oxygen and
manganese. The observed manganese concentrations likely reflect natural
background conditions (soils in the watershed are naturally high in manganese),
although brine from oil wells may also contribute to the elevated concentrations.
Because of the naturally high levels of manganese in the soils, the general use
criterion may be difficult to attain. Causes of low dissolved oxygen typically include
sediment oxygen demand, degradation of CBOD, nitrification of ammonia and/or
algal respiration. Low dissolved oxygen can be exacerbated by low flow and/or high
temperature conditions, similar to what was observed in Skillet Fork. Although the
data were not available to determine the primary causes of low dissolved oxygen,
potential sources of nutrients, ammonia and BOD include failing private sewage
disposal systems (lesser extent), and runoff from agricultural land (fertilized cropland
and agricultural land with livestock).
• For Dums Creek (Segment CAW 01), data are considered sufficient to support the
listing of this segment for dissolved oxygen with four of the five values less than the
criterion. Because there are no point sources in this watershed, low DO is likely
