The Class A1 (primary contact recreation) uses are assessed (monitored) as "partially supported" based on levels of indicator bacteria that exceeded state water quality criteria. The geometric means of indicator bacteria (E. coli) in the 24 samples collected during the recreational seasons of 2014 through 2016 at DNR station 10630003 were as follows: the 2014 geometric mean was 269 orgs/100 ml, the 2015 geometric mean was 443 orgs/100 ml, and the 2016 geometric mean was 927 orgs/100 ml. All three recreation season geometric means exceeded the Class A1 geometric mean criterion of 126 orgs/100 ml. Sixteen of the combined 24 samples (67%) 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 DNR’s assessment/listing methodology, if the geometric mean is greater than 126 orgs/100 ml., the primary contact recreation uses should be assessed as "impaired" (see pgs 3-33 to 3-35 of U.S. EPA 1997b). Thus, because at least one recreation season geometric mean exceeded criteria for Class A1 uses, these uses are assessed as "partially supported."

Results of chemical/physical water quality monitoring at DNR station 10630003 suggest “full support” of the aquatic life uses. Monitoring showedno violations of Class B(WW1) water quality criteria for 35 Ammonia samples (maximum = 0.9 mg/L), 36 Dissolved Oxygen samples (minimum = 6.9 mg/L), 35 pH samples (range = 7.2 to 8.9), 36 Temperature samples (maximum = 28.9° c), 36 Chloride samples (maximum = 150 mg/L), or 36 Sulfate samples (maximum = 79 mg/L) occurred during monitoring from January 2014 to December 2016.According to U.S. EPA guidelines for Section 305(b) water quality assessments (U.S. EPA 1997b, page 3-17), the EPA guidelines allow up to 10% violations of these conventional parameters before impairment of water quality is indicated. Thus, these results thus suggest “full support” of the Class B(WW1) aquatic life uses.

This monitored aquatic life assessment was based on data collected in 2012, 2013 and 2015 as part of the DNR/SHL large river sampling project. A series of biological metrics which reflect stream water quality and habitat integrity were calculated from the biological sampling data. The biological metrics are based on the numbers and types of benthic macroinvertebrate taxa and fish species collected in the stream sampling reach. The biological metrics were combined to make a fish community index of biotic integrity (FIBI) and a benthic macroinvertebrate index (BMIBI). The indexes rank the biological integrity of a stream sampling reach on a rising scale from 0 (minimum) to 100 (maximum). The 2012 BMIBI score was 13 (poor). The 2013 BMIBI scores were 48 and 51 (both fair). The 2015 BMIBI score was 55 (fair). The aquatic life use support was assessed as fully supporting (=FS), based on a comparison of the BMIBI scores with biological impairment criteria (BIC) established for previous Section 305(b) reports. The BMIBI BIC for this ecoregion is 41. The biological impairment criteria were determined from a statistical analysis of biological data collected at stream ecoregion reference sites from 1994-2008. This segment passed the BMIBI BIC 3/4 times in the last five years. This assessment is considered "monitored" because there were two or more samples collected from this segment in multiple years in a recent five year period.

The 2018 IR cycle aquatic life use assessment based on the biological sampling data in the segment changed from "partially supporting" to "fully supporting" (resulting in a proposed de-listing) because of two reasons:

1) This segment spans two different ecoregions; thus, there are different FIBI and BMIBI BICs depending on where the sites fall on the segment. The site used for this segment is located in the 40a ecoregion and the BMIBI BIC for that ecoregion is 41. The 2016 assessment used the 47f BMIBI BIC of 51 and that was assessment error.

2) The 1999 Fisheries Bureau fish sample (FIBI score) should have never been used to assess this stream segment. The sampling site is located close and is highly affected by the Red Rock Reservoir. The 1999 sample only included lake or marsh type of fish species and not stream species. Below is the 2019 explanation from the DNR Fisheries Bureau:

This survey was conducted as part of Federal Aid study 7006: Evaluation of the importance of specific instream habitats to fish populations and the potential for protecting or enhancing Iowa's interior river resources, specifically Job 3: Standing stock of interior river fish populations among specific habitat types.Many of our sampling locations, including the White Breast Creek site, were selected based on a previous study conducted by Vaughn L. Paragamian: Fish populations of Iowa rivers and streams. During Vaughn's study, fish populations at 69 locations in 6 river basins throughout Iowa were sampled with rotenone from 1983-1985. We revisited many of these same sample locations during our study.The White Breast Creek sample site is in the flood plain of Red Rock Reservoir and the section of stream had been previously channelized. Some of Vaughn's study looked at the differences in fish populations in channelized vs non-channelized streams, so that may have been a reason that he picked this particular sample location.Our fish survey was listed as "Fair" sample quality due to turbidity (8" secchi).

The occurrence of a fish kill at this segment in August 2010, also suggests the Class B(WW1) uses should be assessed as "partially supported." A fish kill occurred at this site on August 23, 2010. The kill was a result of a leak from an anhydrous ammonia tank pipe. The cloud was sprayed down with water by the fire department. A road culvert and a tile intake/line allowed the ammonia to reach Mill Branch Creek. Mill Branch Creek flows into Cotton Creek, which then flows into White Breast Creek. Dead fish were observed in all three of these streams below the tile line. The kill affected 10.5 miles of these streams. Approximately 2,784 fish were killed. No information on the species of fish killed was provided. The estimated value of these fish was $12,891.81. DNR sought and received restitution for this fish kill.

According to DNR’s assessment/listing methodology, the occurrence of a single pollutant-caused fish kill, or a fish kill of unknown origin, on a waterbody or waterbody reach during the most recent assessment period indicates a severe stress to the aquatic community and suggests that the aquatic life uses should be assessed as “impaired.” If a cause of the kill is identified, and the cause is either known, or suspected, to be a “pollutant,” the assessment type is considered “monitored” and the affected waterbody is a candidate for Section 303(d) listing. If, however, a consent order has been issued to the party responsible for the kill and monetary restitution has been sought for the fish killed, the affected waterbody will be placed in IR Category 4d (impaired but TMDL not required). DNR feels that (1) TMDLs should not be required for kills caused by a one-time illegal or unauthorized release of manure or other toxic substance where enforcement actions were taken and (2) enforcement action is more appropriate, efficient, and effective for addressing a spill-related impairment than is the TMDL process. Thus, this assessment segment was placed in Category 4d of Iowa’s 2012 Integrated Report. Also based in DNR listing assessment methodology, if no additional kills have been reported for a five-year period, the IR category for the kill will be changed from 4d to 3b (potentially impaired) and added to the state list of waters in need of further investigation.

Fish consumption uses remain "not assessed" due to the lack of recent fish contaminant monitoring in this stream segment.