Cold Springs Lake IA 05-NSH-1420

Cass County S15T75NR37W 1 mi S of Lewis.

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.

Open Segment Map
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Cycle: 2018
Release Status: Final
Overall IR: 1 - All designated uses are met.
Trophic: Eutrophic
Trend: Improving
Created: 3/14/2019 11:06:36 AM
Updated: 3/14/2019 11:10:53 AM

Use Support

Class A1

Recreation - Primary contact

Fully Supported

Class BLW

Aquatic Life - Lakes and wetlands

Fully Supported

Class HH

Human Health -

Fully Supported

General Use

General Use water -

Not Assessed

Impairment Delistings

No delistings for this assessment cycle.

Documentation

Assessment Summary

The Class A1 (primary contact recreation) uses are assessed (monitored) as “fully supported." The Class B(LW) (aquatic life) uses are assessed (monitored) as “fully supported.” Fish consumption uses are assessed (monitored) as “fully supported.” 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) IDNR RAFT fish tissue monitoring.

Assessment Explanation

For the 2018 assessment/listing cycle, the Class A1 (primary contact recreation) uses of Cold Springs Lake are assessed (monitored) as "fully supported" based on information from the ISU lake survey. 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 60, 63, and 63 respectively for Cold Springs Lake. According to Carlson (1977) the Secchi depth, chlorophyll a, and total phosphorus values all place Cold Springs Lake in the Eutrophic category. These values suggest moderately high levels of chlorophyll a and suspended algae in the water, moderately poor water transparency, and moderately high levels of phosphorus in the water column. The data show 3 violations of the Class A1 criterion for pH in 15 samples (20%).

The level of inorganic suspended solids was low at Cold Springs Lake, and does not suggest water quality problems due to non-algal turbidity. The median level of inorganic suspended solids in Cold Springs 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 moderately large population of cyanobacteria exists at Cold Springs Lake. These data show that cyanobacteria comprised 58% of the phytoplankton wet mass at this lake. The median cyanobacteria wet mass (16.5 mg/L) was ranked 72nd of the 138 lakes sampled.

The Class B(LW) (aquatic life) uses are assessed (monitored) as "fully supported." 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 3 violations of the criterion for pH in 15 samples(20%). 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 Cold Springs Lake.

Fish consumption uses were assessed (monitored) as “fully supported” based on results of U.S. EPA/DNR fish contaminant (RAFT) monitoring at Cold Springs Lake in 2012 and 2014.The composite samples of fillets from largemouth bass and channel catfish had moderate levels of contaminants.Levels of primary contaminants in the composite sample of largemouth bass fillets were as follows: mercury: 0.3125 ppm.This composite value is above the 1 meal/week advisory threshold.The levels of mercury generated from this monitoring data are sufficiently high for concern and to justify follow-up monitoring.According to DNR's assessment methodology, the single occurrence of a contaminant above the advisory trigger level neither warrants issuance of an advisory not indicated impairment of the fish consumption uses: two consecutive samplings that show contaminant levels above the trigger level are needed to justify impairment.Levels of primary contaminants in the composite sample of channel catfish fillets were as follows: mercury: 0.0507 ppm; total PCBs: 0.09 ppm; and technical chlordane: <0.03 ppm.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. The fish contaminant data generated from the 2012 and 2014 RAFT sampling conducted at this Cold Springs Lake show that the levels of contaminants do not yet warrant an advisory.

Note: According to Iowa DNR Fisheries Biologists,the clear water and shallow lake basin of Cold Springs Lakes has been ideal for growing aquatic plants. In 2014, a dye treatment was used to suppress aquatic plant growth. It worked very well reducing plant and algae growth down to an acceptable level. The dye treatment was repeated in 2015 with poor results. In 2016 the dye was applied at a higher rate in hopes to repeat 2014 results and it is working. Curly leaf pondweed an invasive plant showed up in Cold Springs a few years ago. Curly leaf pondweed has been on the increase ever since. In other lakes, curly leaf emerges early, crowds out native plants, and dies off in late June promoting algae blooms.

Monitoring and Methods

Assessment Key Dates

6/13/2012

Fixed Monitoring Start Date

9/11/2016

Fixed Monitoring End Date

9/12/2012

Fish Tissue Monitoring

8/3/2012

Fish Tissue Monitoring

8/8/2014

Fish Tissue Monitoring

Methods

120

Surveys of fish and game biologists/other professionals

222

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

260

Fish tissue analysis

340

Primary producer surveys (phytoplankton/periphyton/macrophyton)