Moorehead Park Pond IA 06-LSR-1587

Ida County S10T87NR39W 0.5 mi N of Ida Grove.

Open Data Collection Period Modal

For purposes of developing stream/river water quality assessments for integrated reporting, three years of water quality data are typically used for both conventional pollutant parameters (e.g., indicator bacteria) and the less frequently monitored toxic parameters (e.g., toxic metals). Since the 2004 IR cycle, DNR has used a three-year data gathering period for streams, rivers, and beaches. For most assessments, the use of three years of data increases the number of samples upon which the decision on use support is based and helps address the problem of weather-related year-to-year fluctuations in water quality.

Due to the lower sampling frequency in Iowa’s ambient lake, biological, fish kill, and fish tissue monitoring programs, five years of data are used for developing IR assessments and for identifying Section 303(d) listings.

Data Type	Data Timeframe
Beach Sampling Data	CY 2014 - 2016
Stream/River Water Quality Data	CY 2014 - 2016
Lake Water Quality Data	CY 2012 - 2016
Biological Sampling Data	CY 2012 - 2016*
Fish Kill Data	CY 2012 - 2016
Fish Tissue Sampling Data	CY 2012 - 2016
Continuous Dissolved Oxygen Sampling Data	CY 2012 - 2016
*Biological sites sampled in both 2011 and 2015 were also assessed.

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Cycle: 2018
Release Status: Final
Overall IR: 3 - Insufficient data exist to determine whether any designated uses are met.
Trophic: Eutrophic
Trend: Stable
Created: 4/22/2019 10:35:23 AM
Updated: 4/22/2019 10:38:23 AM

Use Support

Class BLW

Aquatic Life - Lakes and wetlands

WINOFI

Fish Kill: Due To Natural Causes

Support Level

Further Investigation Needed

Impairment Code

3b - Use potentially impaired based on an evaluated assessment.

Cause Magnitude

Slight

Status

Continuing

Source

Natural: Ordinary Stratification and Bottom-Water Hypoxia/Anoxia

Source Confidence

Low

Cycle Added

2008

Impairment Rationale

Non Pollutant-caused fish kill

Data Source

Fish kill investigation: Iowa DNR

Class HH

Human Health -

Not Assessed

General Use

General Use water -

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class B(LW) (aquatic life) uses are assessed (evaluated) as "partially supported." due to a fish kill in 2007. However, in terms of nutrient concentrations, water clarity, and algae populations monitoring data suggest excellent water quality at this lake. Fish consumption uses remain “not assessed” due to a lack of information on which to base an assessment. Sources of data for this assessment include (1) results of the statewide survey of Iowa lakes conducted from 2012 through 2016 by Iowa State University (ISU), (2) information from the IDNR Fisheries Bureau, and (3) results of a fish kill investigation on August 16, 2007.

Assessment Explanation

Using the median values from these surveys from 2012-2016 (approximately 15 samples), Carlson 's (1977) trophic state indices for Secchi depth, chlorophyll a, and total phosphorus were 56, 55, and 61 respectively for Moorehead Lake. According to Carlson (1977) the Secchi depth, chlorophyll a, and total phosphorus values all place Moorehead Lake in the Eutrophic category. These values suggest relatively low levels of chlorophyll a and suspended algae in the water, relatively good water transparency, and moderately high levels of phosphorus in the water column. The data show one violation of the Class A1 criterion for pH in 15 samples (7%).

The level of inorganic suspended solids was low at Moorehead Lake, and does not suggest water quality problems due to non-algal turbidity. The median level of inorganic suspended solids in Moorehead Lake (1.6 mg/L) was ranked 9th among the 138 lakes by the ISU lake survey.

Data from the 2012-2016 ISU lake survey suggest a small population of cyanobacteria exists at Moorehead Lake. These data show that cyanobacteria comprised 9% of the phytoplankton wet mass at this lake. The median cyanobacteria wet mass (2.1 mg/L) was ranked 15th of the 138 lakes sampled.

The Class B(LW) (aquatic life) uses are assessed (evaluated) as "partially supported." due to a fish kill in 2007.Results of the ISU lake survey from 2012-2016 show there were no violations of the criterion for ammonia in 15 samples(0%), no violations of the criterion for dissolved oxygen in 15 samples(0%), and one violation of the criterion for pH in 15 samples(7%). Based on DNR's assessment methodology these violations are not significantly greater than 10% of the samples and therefore suggest (fully supported/monitored) of the Class B(LW) uses of Moorehead Lake.

Results of a fish kill investigation that occurred on August 16, 2007 also suggest “partial support” of the Class B(LW) uses of Moorehead Lake. The fish kill was attributed to low oxygen conditions caused by an algae die-off (natural conditions/non-pollutant). The number and type of fish killed were not reported. This is the same assessment as that developed for the 2008, 2010, 2012, 2014, and 2016 assessment/listing cycle. The continuance of the IR Category 3b listing is based on DNR's 2016 assessment methodology that states the following:the occurrence of a single pollutant-caused fish kill, or a fish kill of unknown origin, on a waterbody or waterbody reach during the most recent assessment period (2014-2014) indicates a severe stress to the aquatic community and suggests that the aquatic life uses should be assessed as “impaired”. If a cause of the kill was not identified during the DNR investigation, or if the kill was attributed to non-pollutant causes (e.g., winterkill), the assessment type will be considered “evaluated” and will be placed in IR subcategories 2b or 3b and will be added to the state list of waters in need of further investigation.

According to the DNR's Fisheries Bureau, the fish population lake was renovated in 2009.

Fish consumption uses remain "not assessed" due to the lack of fish contaminant monitoring in this lake.

Monitoring and Methods

Assessment Key Dates

5/14/2012

Fixed Monitoring Start Date

8/15/2016

Fixed Monitoring End Date

8/16/2007

Fish Kill

Methods

120

Surveys of fish and game biologists/other professionals

140

Incidence of spills and/or fish kills

222

Non-fixed-station monitoring (conventional during key seasons and flows)

340

Primary producer surveys (phytoplankton/periphyton/macrophyton)