Lake Bloomington TMDL-Appendix C
8 September 2007
and Nitrogen Nitrate should include septics and lawn fertilizer runoff.
Response: The list of potential sources in Table 1-1 is taken directly
from the Illinois EPA Integrated Report and is considered a
screening-level assessment of potential sources made at the time of the
original listing. One of the purposes of the TMDL effort was to better
identify specific sources, which now includes septics and lawn
fertilizer runoff.
22. In Section 2.3 Land Use and Land Cover, Paragraph 1 you refer to Figure
2-3, but you mean Figure 2-2. It is puzzling why two categories, forest and
surface water, were lumped together ("1.8 percent...consists of forest or
surface water"), when there would be great value in keeping them
separated. Finally, it should be stated that the Illinois GAP data came from
the Land Cover of Illinois 1999-2000 source so that the reader knows the
relative time frame in which the data was collected.
Response: The reference to Figure 2-2 will be corrected in the report.
The paragraph in question will also be corrected to read “Wetlands
account for approximately 2.5 percent (1,103 acres) of the watershed,
urban lands accounts for 2.5 percent (1,116 acres), and forest lands
(380 acres) are less than 1 percent.”
23. In Section 2.4 Soil and Topography, page 6, second paragraph. "...some
private septic systems may be connected with the drain tile system..." Any
idea how prevalent this is likely to be? Is this informed speculation?
Response: We do not have any specific information on private septic
systems within the watershed that are known to be connected to the
drain tile system. However, such systems have been documented in
other watersheds in Illinois and it is reasonable to believe that they
might exist within the Lake Bloomington watershed as well. If so,
they can be a potentially important source of nutrients.
24. In Section 3.2 Assessment of Water Quality Data, Figure 3-1 is confusing.
STA-3 that is referred to in the text is not on the map. Other figures on the
map (e.g., DKP 03) are not defined in the text.
Response: Thank you for this comment. Station STA-3 has been
added to Figure 3-1 in the final report. The intent of this figure is to
show all of the water quality stations with available data in the
watershed whereas the text is referring to only those stations with a
significant amount of data that were used in the analysis.
25. In Section 4.1 Nonpoint Sources Paragraph 6. It states that "most of them
have valid permits", implying that some do not. Do we know how many
do not?
