Little Volga River IA 01-VOL-328

The presumptive Class A1 (primary contact recreation) uses remain assessed (monitored) as "not supported" based on levels of indicator bacteria that exceeded state water quality criteria. The geometric means of indicator bacteria (E. coli) in the 23 samples collected during the recreational seasons of 2012 through 2014 at the station LVR-10 (STORET station 15330008) were as follows: the 2012 geometric mean was 2,069 orgs/100 ml, the 2013 geometric mean was 784 orgs/100 ml, and the 2014 geometric mean was 399 orgs/100 ml. All three recreation season geometric means exceeded the Class A1 geometric mean criterion of 126 orgs/100 ml. Twenty of the combined 23 samples (87%) 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 geometric mean is greater than 126 orgs/100 ml., the primary contact recreation uses should remain assessed as "impaired" (see pgs 3-33 to 3-35 of U.S. EPA 1997b).

Results of chemical/physical water quality monitoring from 2012 through 2014 do not suggest impairment of the Class B(WW2) aquatic life uses. Monitoring at station LVR-10 showed no violations of Class B(WW2) water quality criteria for ammonia (13 samples), dissolved oxygen (23 samples), pH (23 samples), temperature (22 samples), or chloride (19 samples). Thus, the Class B(WW2) aquatic life uses remain assessed (monitored) as “fully supported”.

A fish kill occurred on September 3, 2002, and resulted from the discharge liquid manure when a pipe failure occurred. The manure flowed to a tributary of the Little Volga River; the Little Volga River was not affected by this kill. Approximately 1.2 miles of this unnamed tributary was affected killing an estimated 12,700 fish. DNR sought and received restitution related to this fish kill. According to DNR's assessment methodology for Section 305(b) reporting, occurrence of a single pollution-caused fish kill during an assessment period indicates "partial support" of the aquatic life uses. 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 should be placed in IR Category 4d (impaired but TMDL not required). Thus, this segment was placed in Category 4d of Iowa’s 2008 Integrated Report. DNR considers IR 4d fish kill waters with no subsequent kills reported in at least five year subsequent to the kill as appropriate for movement from IR Category 4d to either categories 2b or 3b (i.e., Iowa’s list of waters in need of further investigation). Thus, this impairment was moved to Category 3b of Iowa’s 2010 Integrated Report. DNR considers IR Category 4d waterbodies where no additional kills have been reported for this stream for over 10 years, as appropriate for IR Category 3a (not assessed). Thus, this assessment was moved to, and remains in, IR Category 3a Iowa’s integrated report.

Fish consumption uses are assessed (monitored) as “partially supported” based on results of U.S.EPA/DNR fish contaminant (RAFT) monitoring near the Volga State Recreation Area in 2001, 2005, 2007, 2008, 2012, and 2014. Results from these samplings have shown elevated levels of mercury in edible tissue of smallmouth bass such that a restricted consumption advisory was issued by Iowa DNR in 2006; this advisory remains in effect. This advisory recommends consumption of no more than one meal per week of smallmouth bass from this river segment. This advisory extends from the town of Volga upriver to the headwaters of the Volga River near Hawkeye in Fayette County and incudes the Little Volga River and North Branch Volga River. 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. According to DNR’s assessment methodology, the existence of a one-meal-per-week consumption advisory indicates that fish consumption uses should be assessed as “partially supported.”

For the 2001 RAFT sampling, the composite samples of fillets of smallmouth bass contained 0.326 ppm of mercury. The level of mercury in the sample of 2005 composite sample smallmouth bass fillets was 0.545 ppm which also exceeded the DNR/IDPH advisory trigger level of 0.3 ppm for a one meal per week advisory. According to the DNR/IDPH advisory protocol, if two consecutive samplings show that contaminant levels are above the trigger level in fillet samples, issuance of a consumption advisory is justified. This advisory was issued by DNR and IDPH in January 2006 and covered the segments of the Volga River upriver from the county road C2W bridge at Volga in western Clayton County. Follow-up monitoring was conducted as part of the RAFT program in 2007 and 2008. The 2007 samples of smallmouth bass fillets contained 0.24 ppm of mercury; the 2008 sample of smallmouth bass fillets contained 0.33. Because the level of mercury in the 2008 sample exceeded the DNR/IDPH advisory trigger level of 0.3 ppm, the advisory issued in 2006 continued. Results of from the 2012 RAFT showed that levels of mercury in the five smallmouth bass sampled ranged from 0.16 to 0.27 ppm with an average level of mercury of 0.214 (standard deviation of 0.051 ppm). This level of mercury is below Iowa’s threshold for a one mean/week advisory of 0.3 ppm of mercury. According to Iowa’s consumption advisory protocol, however, two consecutive samplings that show levels of fish contaminants are below the advisory threshold are needed to rescind an existing advisory. Thus, follow-up monitoring was conducted in 2014 to better define levels of mercury in this segment of the Volga River and to determine whether the existing advisory should be rescinded. The average level of mercury in tissue plugs from three smallmouth bass was 0.29 ppm. This level of mercury is sufficiently close to the advisory threshold of 0.3 ppm to justify continuing the existing consumption advisory and mercury impairment.