Iowa DNR
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Water Quality Assessments

Impaired Waters List

Raccoon River IA 04-RAC-1116

mouth (at Des Moines Polk Co.) to the Polk/Dallas county line

Assessment Cycle
2018
Release Status
Final
Data Collection Period
Overall IR Category
4 - Water is impaired or threatened and a TMDL has been completed or is not needed.
Trend
Unknown
Created
7/10/2019 8:57:03 AM
Updated
7/10/2019 2:31:05 PM
Assessment conducted in accordance with Iowa's 2018 IR methodology
Use Support
Class A1
Partially Supported
Bacteria: Indicator Bacteria- E. coli
Support Level
Partially Supported
Impairment Code
4a - Pollutant-caused impairment. TMDL has been completed.
Cause Magnitude
Moderate
Status
Continuing
Source
Unknown: Source Unknown
Source Confidence
N/A
Cycle Added
2002
Impairment Rationale
Geometric mean criterion exceeded
Data Source
Ambient monitoring: Corps of Engineers/ISU/UI
Class BWW1
Fully Supported
Class C
Not Supported
Nutrients: Nitrate
Support Level
Not Supported
Impairment Code
4a - Pollutant-caused impairment. TMDL has been completed.
Cause Magnitude
High
Status
Continuing
Source
Agriculture
Source Confidence
Moderate
Cycle Added
1998
Impairment Rationale
Significantly > 10% of samples fail to meet criterion
Data Source
Ambient monitoring: municipal water supply
Class HH
Fully Supported
General Use
Not Assessed
Impairment Delistings
No delistings for this assessment cycle.
Documentation
Assessment Summary

The Class A1 (primary contact recreation) uses are assessed (monitored) as "partially supported" (IR 4a) based on results of monitoring for indicator bacteria (E. coli).  The Class B(WW1) aquatic life uses are assessed (monitored) as "fully supported" (IR 2a) based on results of ambient chemical/physical water quality monitoring.  The Class C (drinking water) uses are assessed (monitored) as "not supported" (IR 4a) due to levels of nitrate that exceed state water quality standards and U.S. EPA’s maximum contaminant level (MCL). Human Health/Fish Consumption uses remain assessed (evaluated) as "fully supported" (IR 2a) based on results of fish contaminant monitoring in 2010 and toxics monitoring from 2012-2014.  The assessments of support of the beneficial uses of this river segment are based on (1) results of monitoring conducted from 2012-2014 by Iowa State University (under contract with the U.S.  Army Corps of Engineers) (ISU/ACOE) conducted at Van Meter (STORET Station 17250001) as part of the Des Moines River Water Quality Study, (2) monitoring conducted on the Raccoon River by the Des Moines Water Works during the 2012-2014 assessment period, (3) results of IDNR/UHL ambient city monitoring upstream from Des Moines at Van Meter (station 10250002) from January 2012 through September 2014, and (4) results of U.S. EPA / IDNR fish tissue (RAFT) monitoring near Booneville in 2010. 

Assessment Explanation

Note: This assessment is also used for the adjacent upstream segment of the Raccoon River (IA 04-RAC-0010-2).

Note: A TMDL for nitrate and pathogen indicators (E. coli) was prepared by DNR and approved by EPA in June 2008. Because this TMDL covered the primary Section 303(d) impairments identified for the 2006 assessment/listing cycle, this waterbody was moved from IR Category 5a from the 2006 assessment/listing cycle to IR Category 4a (impaired; TMDL approved) for the 2008 cycle. This river segment remains in IR Category 4a for the current cycle.

Results from the Des Moines Water Works, ISU/ACOE monitoring station located at Van Meter, and the DNR/UHL station located upstream from Des Moines all suggest that Class A1 uses should be assessed as "partially supported" due to high levels of indicator bacteria.The geometric means of indicator bacteria (E. coli) in the 501 samples collected during the recreational seasons of 2014 through 2016 by the Des Moines Water Works were as follows: the 2014 geometric mean was 352 orgs/100 ml, the 2015 geometric mean was 420 orgs/100 ml, and the 2016 geometric mean was 293 orgs/100 ml. All three recreation season geometric means exceeded the Class A1 geometric mean criterion of 126 orgs/100 ml. 296 of the combined 501 samples (59%) exceeded Iowa’s Class A1 single-sample maximum criterion of 235 orgs/100 ml.The geometric means of indicator bacteria (E. coli) in the 6 samples collected during the 2014 recreational season at DNR station 10250002 (Raccoon River Upstream of Des Moines (US2)) were as follows: the 2014 geometric mean was 930 orgs/100 ml. The recreation season geometric means exceeded the Class A1 geometric mean criterion of 126 orgs/100 ml. Five of the combined 6 samples (83%) exceeded Iowa’s Class A1 single-sample maximum criterion of 235 orgs/100 ml.The geometric means of indicator bacteria (E. coli) in the 50 samples collected during the recreational seasons of 2014 through 2016 ISU/ACOE monitoring station (10250001) located at Van Meter were as follows: the 2014 geometric mean was 430 orgs/100 ml, the 2015 geometric mean was 907 orgs/100 ml, and the 2016 geometric mean was 261 orgs/100 ml. All three recreation season geometric means exceeded the Class A1 geometric mean criterion of 126 orgs/100 ml. Thirty Nine of the combined 50 samples (78%) 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 a recreation season geometric mean exceeds the respective water quality criterion, the 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”. Despite the ongoing impairment of the Class A1 uses, levels of indicator bacteria during the recreation seasons of 2014 through 2016 were relatively low.

The Class B(WW1) aquatic life uses of this river segment are assessed as “fully supporting” based on results of chemical/physical water quality data. Results of chemical/physical water quality monitoring at DNR station 10250002 (Raccoon River Upstream of Des Moines (US2)) suggest “full support” of the aquatic life uses. Monitoring showedno violations of Class B(WW1) water quality criteria for 9 Ammonia samples (maximum = 0.3 mg/L), 9 Dissolved Oxygen samples (minimum = 7.7 mg/L), 9 pH samples (range = 7.5 to 8.5), 9 Temperature samples (maximum = 23.3° c), 9 Chloride samples (maximum = 36 mg/L), or 9 Sulfate samples (maximum = 67 mg/L) occurred during monitoring in 2014.Results of chemical/physical water quality monitoring ISU/ACOE monitoring station (10250001) located at Van Meter also suggest “full support” of the aquatic life uses. Monitoring showedno violations of Class B(WW1) water quality criteria for 66 Ammonia samples (maximum = 0.9 mg/L), 66 Dissolved Oxygen samples (minimum = 6.1 mg/L), 66 pH samples (range = 7.4 to 8.9), 66 Temperature samples (maximum = 28.9° c), 12 Chloride samples (maximum = 38.4 mg/L), or 12 Sulfate samples (maximum = 56.8 mg/L) occurred during monitoring from January 2014 to December 2016.Results of chemical/physical water quality monitoring by the Des Moines Water Works also suggest “full support” of the aquatic life uses. Monitoring showedno violations of Class B(WW1) water quality criteria for 738 Temperature samples (maximum = 28.9° c), 819 Chloride samples (maximum = 261.6 mg/L), or 825 Sulfate samples (maximum = 82.6 mg/L) occurred during monitoring from January 2014 to December 2016.3 of the 755 samples (0%) analyzed for pH (range = 7.5 to 9) violated the Class B(WW1) criteria during the 2014-2016 monitoring period. According to U.S. EPA guidelines (U.S. EPA 1997b, page 3-17) and Iowa DNR's assessment/listing methodology, a violation frequency of significantly greater than 10% for conventional parameters such as pH suggests impairment of aquatic life uses. Because the frequency of violations for this parameter is not greater than 10 percent, these results do not suggest impairment of the Class B(WW1) aquatic life uses.

Results of water quality monitoring for Toxics atISU/ACOE monitoring station (10250001) located at Van Meter also suggest “full support” of the aquatic life uses. Monitoring showedno violations of Class B(WW1) acute or chronic water quality criteria for 4 Copper samples (maximum = 3.9 ug/L) occurred during monitoring from March 2016 to December 2016 and 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 1 acute violations of these Toxic parameters before impairment of water quality is indicated. Thus, these results thus suggest “full support” of the Class B(WW1) aquatic life uses.

The Class C (drinking water) uses are assessed as "not supporting".Results of Class C(drinking water) monitoring by the Des Moines Water Works suggest “no support” of the drinking water uses. Monitoring showed no violations of Class C(drinking water) criteria for 821 Fluoride samples (maximum = 2000 ug/Land average = 327.66 ug/L) occurred during monitoring from January 2014 to December 2016.2 of the 820 samples (0%) analyzed for Chloride (maximum = 261.6 mg/Land average = 24.9 mg/L) and 455 of the 821 samples (55%) analyzed for nitrite+nitrate(maximum = 19.38 mg/Land average = 9.77 mg/L) violated the Class C(drinking water) criteria during the 2014-2016 monitoring period.According to DNR's assessment guidelines, the DMWW data suggest that the Class C drinking water uses should be assessed as "not supported".

Results of Class C(drinking water) monitoring ISU/ACOE monitoring station (10250001) located at Van Meter also suggest “no support” of the drinking water uses. Monitoring showedno violations of Class C(drinking water) criteria for 12 Chloride samples (maximum = 38.4 mg/Land average = 24 mg/L) occurred during monitoring from January 2014 to December 2016.36 of the 66 samples (55%) analyzed for nitrite+nitrate(maximum = 22.4 mg/Land average = 10.06 mg/L) violated the Class C(drinking water) criteria during the 2014-2016 monitoring period.Results of Class C(drinking water) monitoring at DNR station 10250002 (Raccoon River Upstream of Des Moines (US2)), however, suggest “full support” of the drinking water uses. Monitoring showed noviolations of Class C(drinking water) criteria for 9 Chloride samples (maximum = 36 mg/Land average = 24.1 mg/L), 9 nitrite+nitratesamples (maximum = 9.3 mg/Land average = 4.99 mg/L), 14 Alachlor samples (maximum = 0.05 ug/Land average = 0.03 ug/L), 7 Atrazine samples (maximum = 1.5 ug/Land average = 0.49 ug/L), 7 Carbofuran samples (maximum = 0.05 ug/Land average = 0.05 ug/L), or 7 Cyanazine samples (maximum = 0.05 ug/Land average = 0.05 ug/L) occurred during monitoring from January 2014 to September 2014. Despite the results of DNR monitoring that suggest “full support”, the more robust datasets from the ISU/ACOE and DMWW monitoring networks strongly suggest that the Class C (drinking water) uses should be assessed as impaired.

Fish consumption/human-health uses remain assessed (monitored) as “fully supported” based on results of U.S. EPA/DNR fish contaminant (RAFT) monitoring at the Raccoon River near the Booneville access in 2010 and based on results of monitoring for toxics from 2012 to 2014. The 2010 composite samples of fillets from common carp and flathead catfish had low levels of contaminants. Levels of primary contaminants in the composite sample of common carp fillets were as follows: mercury: 0.105 ppm; total PCBs: 0.09 ppm; and technical chlordane: <0.03 ppm. Levels of primary contaminants in the composite sample of flathead catfish fillets were as follows: mercury: 0.152 ppm. The existence of, or potential for, a fish consumption advisory is the basis for Section 305(b) assessments of the degree to which Iowa’s lakes and rivers support their fish consumption uses. The fish contaminant data generated from the 2010 RAFT sampling conducted at this river segment show that the levels of contaminants do not exceed any of the advisory trigger levels, thus indicating no justification for issuance of a consumption advisory for this waterbody.

Results of Class HH(human health) monitoring ISU/ACOE monitoring station (10250001) located at Van Meter also suggest “full support” of the human health uses. Monitoring showedno violations of Class HH(human health) criteria for 4 Copper samples (maximum = 3.9 ug/L) occurred during monitoring from March 2016 to December 2016.According to DNR’s assessment/listing methodology, if the mean level of a toxic metal or pesticide is greater than its respective human health criterion, impairment (“nonsupport”) of the Human Health use is indicated. Thus, these results thus suggest (“full support”) of the Class HH(human health) uses.


Monitoring and Methods
Assessment Key Dates
1/2/2014 Fixed Monitoring Start Date
12/30/2016 Fixed Monitoring End Date
9/3/2010 Fish Tissue Monitoring
Methods
230 Fixed station physical/chemical (conventional plus toxic pollutants)
260 Fish tissue analysis
270 PWS chemical monitoring (ambient water)
420 Indicator bacteria monitoring