Princeton State Wildlife Area IA 01-WPS-331

Results of water quality monitoring conducted at Princeton State Wildlife Area (Wetland 34) indicate that the aquatic life uses should be assessed (evaluated) as "not supported" due to high levels of algae at this lake. This assessment is considered "evaluated" because only 7 samples were collected during the current assessment period (2014-2016). Based on DNR's assessment methodology, 9 samples within the most recent three year period are necessary to accurately characterize water quality for the purposes of identifying impaired waters

Guidelines for wetland assessment from the Upper Mississippi River Conservation Committee’s Water Quality Technical Section (2003) state that an average total suspended solids concentration during the growing season of less than 30 mg/L is necessary to provide sufficient water clarity to support the growth of submersed aquatic vegetation in wetlands and shallow lakes. High levels of total suspended solids impede the growth of submersed aquatic vegetation (SAV). Submersed aquatic vegetation is critical to the health of wetland and shallow lake ecosystems. The elimination of SAV can degrade habitat quality such that undesirable aquatic species such as cyanobacteria, common carp and fathead minnows dominate. As such, the suppression of SAV constitutes a violation of Iowa’s narrative water quality criteria protecting against undesirable or nuisance aquatic life.

Using the overall median values from the DNR shallow lakes and wetlands monitoring program from 2014 through 2016 (approximately 9 samples), the median growing season total suspended solids concentration was 21.5 mg/L; this median value is below the UMRCC guideline and suggests "full support" of the aquatic life uses.

In addition, the level of algae also suggests "full support" of the aquatic life uses atPrinceton State Wildlife Area (Wetland 34). The Carlson’s (1977) trophic state index value for chlorophyll a was 70. According to Carlson (1977), the index value for chlorophyll a places Barringer Slough in the hypereutrophic category. This value suggests extremely high levels of chlorophyll a and suspended algae in the water and "no support" of the aquatic life uses.

NOTE:The TSI value for Secchi depth is not used to evaluate the attainment of aquatic life goals in shallow lakes. Due to the depth of these shallow lakes, TSI values for Secchi depth can be misleading. In some instances the Secchi disk remains visible at the bottom of the lake and the depth of the lake is recorded as the Secchi depth. In these instance, water clarity may be sufficient to support the Class B(LW) uses, but the index value is limited by the depth of the lake. Thus the combination of total suspended solids and chlorophyll a will be used to determine whether or not the Class B(LW) uses are impaired in these shallow systems.

The aquatic life uses remain assessed (evaluated) as "partially supported" based on information from the Iowa DNR Wildlife Bureau (see assessment for the 1998 and 2000 reports). The assessment category for this wetland of "evaluated" indicates that the assessment is based entirely on "best professional judgment."In terms of Section 305(b) reporting, "monitored assessments" are based primarily on recent, site-specific ambient monitoring data and thus have relatively high confidence. DNR considers waterbodies identified as "impaired" based on "monitored assessments" as candidates for the state's Section 303(d) list. "Evaluated assessments" are those based on data older than five years or other than site-specific ambient monitoring data (e.g., questionnaire surveys of fish and game biologists [=best professional judgment]) and thus have relatively lower confidence. DNR does not consider waterbodies identified as "impaired" based on "evaluated assessments" as candidates for the state's Section 303(d) list.

Note:This waterbody is not in Iowa's current surface water classification and is thus classified only for general uses. As such, only the general use protection for aquatic life will be assessed.