Lizard Creek IA 04-UDM-1278

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 23 samples collected during the recreational seasons of 2012 through 2014 at DNR station 10940001 near Fort Dodge were as follows: the 2012 geometric mean was 58 orgs/100 ml, the 2013 geometric mean was 154 orgs/100 ml, and the 2014 geometric mean was 414 orgs/100 ml. Two of the three recreation season geometric means exceeded the Class A1 geometric mean criterion of 126 orgs/100 ml. Seven of the combined 23 samples (30%) 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."

The Class B(WW1) aquatic life uses are assessed (monitored) as "partially supported" based on 2012-2015 DNR/SHL biological sampling data and results of the 1998-99 statewide survey of freshwater mussels. The 2015 FIBI score was 69 (good). The 2012-2015 BMIBI scores were 33, 51, 53 (all fair) and 60, 63 (both good). The aquatic life use support was assessed as partially supporting (=PS), based on a comparison of the FIBI and BMIBI scores with biological impairment criteria (BIC) established for previous Section 305(b) reports. The biological impairment criteria were determined from a statistical analysis of data collected at stream ecoregion reference sites from 1994-2008. The riffle-site FIBI BIC for this ecoregion is 53 and the BMIBI BIC for this ecoregion is 62. This segment passed the FIBI BIC 1/1 times and passed the BMIBI BIC 1/5 times in the last five years.

This aquatic life assessment is now considered "monitored" based on a change in the 2010 DNR assessment methodology. DNR now requires a segment have two or more biological samples collected from the segment in multiple years over a recent five-year period to be considered “monitored”. This segment had multiple BMIBI samples collected in the previous five years (2012-2016).

The results of the statewide assessment of freshwater mussels also suggest the potential for an impairment of the aquatic life uses due to a decline in the community of freshwater mussels in this stream segment. This segment of Lizard Creek was sampled as part of the 1998-99 statewide study of freshwater mussels in Iowa streams and rivers (Arbuckle et al. 2000). As part of this study, sampling results from 1998 and 1999 (Arbuckle et al. 2000) were compared to results from stream sites surveyed in 1984 and 1985 by Frest (1987). On a statewide basis, this comparison showed sharp declines in the numbers of mussel species ("species richness") in Iowa streams and rivers from the mid-1980s to the late 1990s. For stream segments having four or more species reported for the 1984-95 survey, results of this comparison were used by staff of the DNR Water Quality Bureau to assess the degree to which the aquatic life uses of the sampled stream segments are supported. The results of this sampling on this segment of Lizard Creek, however, do not meet DNR guidelines for developing a monitored assessment of support for the aquatic life uses that is appropriate to support addition of this waterbody to Iowa's Section 303(d) list. That is, 303(d)-level assessment decisions are developed only for those stream segments having an average of four or more species reported in the 1984-85 (Frest) survey due to the difficulty of interpreting status of mussel communities showing relatively low species richness during the both the historical (1984-85) and current (1998-99) surveys. This information can be used, however, to indicate the potential for an impairment of the aquatic life uses and to indicate the need to conduct additional sampling. Species richness of freshwater mussels at the four sample sites in this segment of Lizard Creek was 0, 1, 2, and 3 in the 1984-85 period and was 0, 1, 0, 0 in the 1998-99 period, respectively, for an average 1984-85 species richness of approximately 2 and a percent change of minus 50%. Based on these results, the aquatic life uses are assessed (evaluated) as “partially supported."

Results of chemical/physical water quality monitoring at DNR station 10940001 near Fort Dodge, however, suggest “full support” of the aquatic life uses. Monitoring showed no violations of Class B(WW1) water quality criteria for 33 Ammonia samples (maximum = 1.4 mg/L), 33 Dissolved Oxygen samples (minimum = 8.3 mg/L), 33 pH samples (range = 7.3 to 8.7), 33 Temperature samples (maximum = 27° c), 33 Chloride samples (maximum = 120 mg/L), or 33 Sulfate samples (maximum = 200 mg/L) occurred during monitoring from January 2012 to September 2014.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.

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