Holland Creek IA 02-CED-6491
from confluence with unnamed tributary in NE1/4 S29 T88N R17W Grundy Co. to headwaters in NE1/4 S26 T88N R18W Grundy Co.
- Cycle
- 2016
- Release Status
- Final
- Overall IR
- 5 - Water is impaired or threatened and a TMDL is needed.
- Trend
- Unknown
- Created
- 8/16/2016 4:24:13 PM
- Updated
- 12/1/2016 3:08:51 PM
The presumptive Class A1 (primary contact recreation) uses remain assessed (monitored) as “not supported” (IR 5p) due to violations of Iowa water quality criteria for indicator bacteria. The Class B(WW1) aquatic life uses remain “not assessed” (IR 3a) due to the lack of water quality information upon which to base an assessment. The source of data for this assessment remains the results of monitoring at one site (BHC-2) conducted as part of a Clean Water Act Section 319 water quality project from June 2009 through November 2010. This is the same assessment as developed for previous IR cycles.
The presumptive Class A1 uses remain assessed (monitored) as “not supported” due to levels of indicator bacteria (E. coli) that exceed the Class A1 geometric mean criterion. The geometric means of indicator bacteria (E. coli) in the 22 samples collected during the recreational seasons of 2009 and 2010 at the Section 319 monitoring station BHC-2 were 1,054 and 147 orgs/100 ml, respectively. Both of these recreation season geometric means exceed Iowa’s Class A1 geometric mean criterion of 126 E. coli orgs/100 ml, thus indicating nonsupport of the Class A1 primary contact recreation uses. Thirteen of the 22 samples (59%) exceeded Iowa’s Class A1 single-sample maximum criterion of 235 orgs/100 ml. According to U.S. EPA guidelines for Section 305(b) reporting and IDNR’s assessment/listing methodology, if a recreation season geometric mean is greater than the respective criterion (126 orgs/100 ml for Class A1, the primary contact recreation uses should be assessed as "impaired" (see pgs 3-33 to 3-35 of U.S. EPA 1997b). In addition, the percentage of samples with levels of E. coli that exceeded Iowa single-sample maximum criteria indicate impairment of Class A1 uses at this monitoring site.