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Problems
Segment 1246 failed to meet the designated uses established
by the State of Texas in the mid-1990s. Nitrogen levels
in the surface water exceeded screening levels on 100
percent of the TCEQ samples collected for the 1996 State
of Texas Water Quality Inventory (section 305(b) report).
Although, the segment did not appear on section 303(d)
lists for 1998 or 2000, it is listed as having a nutrient
enrichment concern with respect to NO2-N+NO3-N
in the TCEQ 2002 draft assessment of use impairments
and concerns, with one of its subsegments listed for
not supporting the contact recreation use due to bacteria.
Ammonium perchlorate has been detected in surface waters
associated with the Naval Weapons Industrial Reserve
Plant near McGregor in the South Bosque River watershed.
Exposure to ammonium perchlorate is associated with
potential health problems, leading to some concern about
its possible presence in Lake Waco, which is the drinking
water source for the City of Waco and other communities.
Objectives
The purpose of this study was to investigate two potential
sources of the elevated NO2-N
+ NO3-N
concentrations in surface waters of the South Bosque
River watershed. The two sources investigated were remnants
from past activities at the NWIRP and current agricultural
practices. Other potential sources were not considered
in this study.
Methods
TIAER conducted a monitoring program to collect data
from stream sites containing varying percentages of
NWIRP influence and cropland within the drainage areas.
Statistical analyses of the NO2-N+
NO3-N concentrations,
location with respect to the NWIRP, and land uses associated
with the contributing drainage area to each site were
used to investigate relationships between water quality
and land cover and the NWIRP.
Papers
Assessment of the Middle and South Bosque River Watersheds: Final Report to the Texas State Soil and Water Conservation Board for the Section 319(h) project: Middle and South Bosque Assessment Project, This paper further expands the previous study by utilizing updated land use data to focus on the possible sources of the elevated soluble nitrogen levels in the surface and groundwater of the study area. In addition, a secondary objective was to provide information on ammonium perchlorate. Comprehensive information on health effects associated with exposure to the compound and its degradation products are provided.
Special Study of Nitrogen in Surface Waters of the South Bosque River Watershed, This study investigated two potential sources of high NO2 + NO3 concentrations in surface waters of the South Bosque River watershed. The two sources investigate include 1) remnants from past activities at the Naval Weapons Industrial Reserve Plant and 2) current agricultural practices. No other potential sources were considered in this study.
Existing Nutrient Sources and Contributions to the Bosque River Watershed, Over about a two and a half-year period (November 1, 1995 March 30, 1998), flow and nutrients were monitored consistently at 17 sites in the Bosque River watershed, which includes the Middle and South Bosque drainage areas. An empirical model was developed to assess nutrient contribution by source using developed export coefficients for nonpoint sources and information from the eight permitted municipal wastewater treatment plants within the watershed for point source loadings. Sites within the South and Middle watersheds were important in determining nutrient contributions from row-crop agriculture.
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