Fort Des Moines Park Pond IA 04-LDM-1099

Assessment Comments

Assessment remains based on results of Iowa DNR fish contaminant monitoring in August 2007 and July 2010.

Basis for Assessment

SUMMARY: The Class B(LW) (aquatic life) uses remain "not assessed" due to a lack of water quality monitoring at this lake.    The fish consumption uses remain assessed (monitored) as "fully supporting" based on results of IDNR fish contaminant monitoring in August 2007 and July 2010.    

EXPLANATION:  The Class B(LW) (aquatic life) uses remain "not assessed" due to a lack of water quality monitoring at this lake.    

Fish consumption uses remain assessed (monitored) as “fully supported” based on results fish contaminant monitoring conducted by Iowa DNR at this lake in August 2007 in response to a contaminant concern.   Additional follow-up monitoring was conducted in July 2010  Fish contaminant monitoring conducted by Iowa DNR in 1995 had shown a level of the pesticide methoxychlor that, although not exceeding any consumption advisory trigger levels, did suggest the need for follow-up monitoring.   The results of monitoring in 2007 showed low levels of the primary contaminants in the composite samples of fillets from largemouth bass and channel catfish.   Levels in the sample of largemouth bass fillets were as follows:  mercury: 0.27 ppm; DDD: 0.024 ppm; and DDE: 0.038 ppm.    Levels in the sample of channel catfish fillets were as follows: mercury: 0.027 ppm; DDD: 0.025 ppm; and DDE: 0.030 ppm.   Although analyzed for, methoxychlor was not detected in either sample.    Levels of the DDT metabolites DDD and DDE in the Fort Des Moines Pond tissue samples were typical of levels seen in other samples of Iowa fish and do not suggest a risk to human health.    

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 levels of contaminants in the samples collected in 2007 from Fort Des Moines Park Pond do not exceed any of the IDPH/IDNR advisory trigger levels, thus suggesting no justification for issuance of a consumption advisory for this waterbody.   The level of mercury in the sample of largemouth bass (0.27 ppm) does, however, approach Iowa's trigger level for a one meal per week advisory (0.3 ppm).    Thus, Iowa DNR plans to conduct follow-up monitoring at this lake on an every-other-year basis to monitor levels of mercury in largemouth bass.   Follow-up monitoring was conducted in July 2010.   The level of mercury in the sample of largemouth bass fillets (0.244 ppm) is below the IDPH/IDNR advisory trigger level and therefore suggests that the fish consumption uses remain assessed (monitored) as "fully supported."