Division of Surface Water Glossary for 2010 Integrated Report Assessments

General Information

HUC12:  The U.S. Geological Survey designated 12-digit hydrologic unit code for Ohio's 1,538 watershed assessment units (WAUs).

WAU/LRAU/Lake Erie AU Description:  A geographic description of the watershed, large river, or Lake Erie assessment units.

WAU/LRAU Size:  The watershed drainage area of the assessment unit in square miles.

Integrated Report Assessment Category:  One of five categories assigned to indicate the status of designated uses. The categories and their definitions are as follows.

Category1Subcategory
0No waters currently utilized for water supply 
1Use attaininghHistorical data
xRetained from 2008 IR
2Not applicable in new (2010) Ohio system 
3Use attainment unknownhHistorical data
iInsufficient data
xRetained from 2008 IR
4Impaired; TMDL not neededATMDL complete
BOther required control measures will result in attainment of use
CNot a pollutant
hHistorical data
nNatural causes and sources
xRetained from 2008 IR
5Impaired; TMDL neededMMercury
hHistorical data
xRetained from 2008 IR

1Shading indicates categories defined by U.S. EPA; additional categories and subcategories are defined by Ohio EPA.

Priority Points:  A number between 1 and 20, calculated if any of the use assessment categories is 5 (or the assessment unit is not impaired but is on the nitrate and/or pesticide watch lists for public drinking water supply). Otherwise, blank. See Section J2 for an explanation of how the points are determined.

Next Scheduled Monitoring:  The year in which Ohio EPA expects to revisit the assessment unit for comprehensive monitoring.


Aquatic Life Use (ALU) Assessment

See Section G for a detailed explanation of the assessment process

Subcategories of ALU:  The designated aquatic life uses as codified in the Ohio Water Quality Standards - EWH (Exceptional Warmwater Habitat), WWH (Warmwater Habitat), CWH (Coldwater Habitat), MWH-C (Modified Warmwater Habitat-Channelized), MWH-MD (Modified Warmwater Habitat-Mine Drainage), MWH-I (Modified Warmwater Habitat-Impounded), LRW/LRW-S (Limited Resource Water), LWH/WWH-L (Limited Warmwater Habitat), SSH (Seasonal Salmonid Habitat).

Sampling Years:  Years with data available for specific streams and rivers within the assessment unit that were used to assess status of the designated aquatic life use(s).

Impairment:  Yes (Reporting Categories 4 or 5), No (Reporting Category 1), or Unknown (Reporting Category 3) depending on the assessment of the available sampling locations and their designated aquatic life use.

Data Assessment Summary (WAUs):  Available site data from the assessment unit are grouped according to 3 stream size categories (headwater, wading, and principal) based on drainage area in square miles at the sampling location. The Watershed Score is generated based on the proportion of sampling locations which are in full attainment of the designated aquatic life use in each size category. The full attainment proportions of the headwater and wading categories are averaged to compute an intermediate WAU score. This number is then averaged with the principal full attainment proportion to derive the overall Watershed Score. This weighting method is used to impart more significance to sites in the largest drainage class (principal streams).

Data Assessment Summary (LRAUs and Lake Erie AUs):  Attainment statistics (Miles in Full, Partial, or Non-Attainment) were generated based on a linear extrapolation of full, partial, or non-attaining miles to the total number of monitored river miles (for LRAUs) or the proportion of shoreline sampling sites in full, partial, or non-attainment for the Lake Erie AUs. The Assessment Unit Score is the proportion of monitored miles (LRAUs) or sites (Lake Erie AUs) in full attainment of the designated aquatic life use.

Causes of Impairment:  The listing of the most prominent "agents" deemed responsible for the observed aquatic life use impairment in the assessment unit if in Reporting Category 4 or 5 and which will be the initial focus of restoration activities or TMDL development within the watershed. None Listed if the assessment unit is unassessed (Reporting Category 3 or the aquatic life uses are unimpaired (Reporting Category 1).

Sources of Impairment:  The listing of the most prominent origins of the "agents" (causes of impairment) deemed responsible for the observed aquatic life use impairment.


Recreation Use Assessment (WAUs and LRAUs)

See Section F for a detailed explanation of the assessment process

Subcategories of Recreation Use:  "Primary Contact" refers to waters that are suitable for full-body contact recreation, such as swimming, canoeing and diving during the recreation season. There are three classes of primary contact recreation ranging from Class A, which support frequent recreation, Class B, which support occasional recreation activity, to Class C, which support infrequent recreation activity. "Secondary Contact" are those waters that are rarely used for recreation because of limited access and generally having physical limitations that would limit water ingestion potential associated with recreation.

Impairment:  Yes, No, or Unknown depending on the assessment of the available data from sampling locations within the assessment unit.

Geometric Mean:  The geometric mean of all available E. coli bacteria data collected from a specific location and collected within the same recreation season, computed as the arithmetic mean of the log-transformed data.


Public Drinking Water Supply (PDWS) Use Assessment

See Section H for a detailed explanation of the assessment process

PDWS Use Designations and PWS:  The Public Drinking Water Supply (PDWS) beneficial use only applies within 500 yards of active drinking water intakes, all publicly owned lakes, all privately owned lakes and reservoirs used as a source of public drinking water, and all surface waters used as emergency water supplied. All current PDWS use zones were described and the associated public water systems identified as [PWS Name]. Only waters with active PWS intakes were assessed at this time.

Overall PDWS Use Support:  This determination (Yes/No/Unknown) was based on all assessment results from all PDWS zones in the AU. In order to be considered in overall Full Support (Yes), sufficient data were required for assessment of at least the nitrate indicator at all PDWS zones in the AU. In order for each indicator status to be considered "Full Support," sufficient data were required for all PDWS zones within the AU. Pesticide information was included when sufficient data were available. If any zones were identified as "Impaired" for any indicator, it would trigger an overall status of "Not Support."

Watch list:  In addition to assessment of impairment status, water quality data were evaluated at each zone to identify waters in need of additional monitoring. These trigger points are more conservative than the water quality criteria used for the impairment determinations. Waters with at least one nitrate detection > 8 mg/L or pesticide levels > 3X the WQC (instantaneous) or quarterly pesticide average > annual average criteria were identified on the watch list.


Human Health (Fish Tissue) Use Assessment

See Section E for a detailed explanation of the assessment process

Results of comparing fish tissue contaminant data to the single route exposure human health water quality criteria in Ohio's Water Quality Standards.

Reporting Category:  See "Integrated Report Assessment Category" table at the beginning of this document for an explanation of reporting categories used in the human health/fish tissue use assessment.

Causes of Impairment:  Mean fish tissue concentrations of PCBs, mercury, DDT, hexachlorobenzene, chlordane, and mirex were evaluated for each assessment unit where data were available. If any of the listed contaminants exceeded the mean concentration in fish tissue on which the single route exposure human health water quality criterion is based, that assessment unit was considered impaired for that contaminant.

Contaminant Concentration:  Mean concentration in fish tissue of the contaminant(s) for which the assessment unit is impaired. Impairment concentration thresholds for each contaminant are listed in Table x.x of this document.