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Lake Greenwood Fish Kill (April 13-20, 2026)

State and local officials were notified of a fish kill in Lake Greenwood after receiving public reports of several dead fish in the Cross Hill area of the lake. Reports of dead fish were received from April 13-20. As provided in the updates below, routine monitoring data and specialized sampling data do not indicate a concern for consuming fish or recreating in the lake.    

This webpage will continue to be updated to provide new information. Additional information can be provided to SCDES using our online ReportIt! tool (des.sc.gov/ReportIt) or contacting the agency at (803) 898-3432.

The South Carolina Department of Environmental Services (SCDES) this week received the final round of fish tissue testing results for Lake Greenwood. Three organochlorine pesticides or pesticide breakdown products were found in three Lake Greenwood fish tissue samples. However, these specific pesticides (or byproducts of them) have all been banned since the 1970s or 1980s and are known to accumulate and persist in soils, sediment and the food chain.  

It’s unlikely the presence of these pesticides contributed to the April fish kill. Fish tissue studies performed by the U.S. Geological Survey (USGS), as noted below, have identified these chemicals in fish sampled from streams and lakes throughout the country.  

Next steps 

SCDES is working to finalize a report that details all of SCDES's activities related to the April 13-20 fish kill investigation. Once finalized, the report will be posted publicly on this webpage.   

Additionally, SCDES will perform an After Action Review (AAR) of this fish kill response and investigation. This AAR will unite SCDES and SCDNR with third-party academic experts to review the investigation report and comprehensive data that could help identify a possible probable cause or causes of the April fish kill. AARs are commonly held after environmental responses to help all responding entities evaluate procedures and resources that were utilized during the investigation. 

Detailed final fish tissue sample results 

As a reminder, SCDES had collected fish tissue samples of different species of fish as part of the April fish kill investigation. These samples were sent to an independent lab to perform contaminant testing that included a suite of trace metals, organochlorine pesticides, organophosphate pesticides and organics. 

For this final round of results, a total of 16 organochlorine pesticides were tested in five Lake Greenwood fish tissue samples. As noted above, three organochlorine pesticide compounds or breakdown byproducts were detected in three of the samples: dieldrin, heptachlor epoxide, and p,p’-DDE. These three chemicals are primarily stored in fat tissues of fish.  
 
Summary:  

  • Dieldrin, heptachlor epoxide, and p,p’-DDE were detected in the dead fish whole-tissue composite sample 
  • p,p’-DDE was detected in the largemouth bass whole fish composite sample and the channel catfish fillet. 

Dieldrin is an organochlorine pesticide that was banned in the late 1980s. It was often used on crops and for termite control. It is a highly persistent chemical that accumulates readily in the food chain. Dieldrin was detected in the Lake Greenwood dead fish sample with a concentration of 43 µg/kg. A national study by the USGS detected dieldrin in 45% of whole fish samples with a maximum concentration of 180 µg/kg in mixed land use watersheds (USGS 2006). 

Heptachlor epoxide is a byproduct of the breakdown of the insecticide heptachlor. Most uses of heptachlor were banned by 1988; however, heptachlor epoxide is a highly persistent chemical that accumulates readily in the food chain and can remain in soils for years. The same USGS study detected heptachlor epoxide in 15% of fish samples with a maximum concentration of 22 µg/kg in mixed land use watersheds (USGS 2006). The concentration of heptachlor epoxide in the Lake Greenwood dead fish sample was 13 µg/kg. 

The compound p,p’-DDE is a breakdown product of DDT, a widely used insecticide banned in 1972. p,p’-DDE bioaccumulates in the food web and is highly persistent in the environment. This compound was detected in three Lake Greenwood fish tissue samples, with the highest concentration of 210 µg/kg in the dead fish sample. The other detections for p,p’-DDE were the whole-body largemouth bass sample (79 µg/kg) and the channel catfish fillet (84 µg/kg). These concentrations are within reported ranges from the USGS study where p,p’-DDE was detected in 90% of samples and had a maximum value of 7,200 µg/kg in mixed land use watersheds (USGS 2006). 

The compound p,p’-DDE is part of a pesticide class that is known to persist in soils and sediments. The dead fish sample with the highest concentration of p,p’-DDE was collected along the shore where the pesticide possibly could have accumulated in soil or sediment.  

Organochlorine pesticides testing panel: 

 

Reference: USGS. 2006. Pesticides in the Nation's Streams and Ground Water, 1992–2001 (Revised Feb 2007): U.S. Geological Survey Circular 1291. https://doi.org/10.3133/cir1291

The S.C. Department of Environmental Services (SCDES) and S.C. Department of Natural Resources (SCNDR) have received results of comprehensive fish testing for Lake Greenwood. While most results have been received and are provided in the report below, some additional results are pending and will be shared when available.  

SCDES Fish Sampling    
SCDES collected fish tissue samples as part of the April fish kill investigation. These samples were sent to an independent lab to perform contaminant testing that included a suite of trace metals, organochlorine pesticides, organophosphate pesticides, and organics. In total, SCDES received results for more than 80 compounds. The results from this extensive sampling were received this week and are available in a detailed report provided here.

A summary of the results follows; please see the full detailed report above. 

  • Trace Metals: All samples were below laboratory reporting limit for arsenic, cadmium, lead, selenium, and tin. 

  • Mercury: Mercury was above laboratory reporting limit in five of 13 samples. These results that are above laboratory reporting limit are consistent with historical statewide and Lake Greenwood monitoring data. 

  • Organochlorine Pesticides and Organophosphorus Pesticides: Organophosphorus pesticides were tested on nine total samples with at least one sample for each species and sample type (fillet and whole-tissue composite). All samples were below laboratory reporting limits for all 26 organophosphorus pesticides. Organochlorine pesticide results are pending. 

  • Polychlorinated Biphenyls (PCBs): All seven polychlorinated biphenyls (PCBs) mixtures were below reporting limit for the dead fish composite sample. PCBs were not tested on additional samples since historically PCBs have not been present fish in tissue on Lake Greenwood. 

  • Polycyclic aromatic hydrocarbons (PAHs): All 16 polycyclic aromatic hydrocarbons (PAHs) were below reporting limits for all 13 samples. 

  • Dioxins and Furans: A total of 25 individual or total dioxin and furan compounds were tested on the post-mortem decomposing whole fish sample. One compound and its corresponding ‘total’ value were above reporting limit. According to EPA, a national study showed this furan (2,3,7,8-TCDF) was detected in 89% of sites sampled for fish tissue. The concentration detected is within the known range for this compound. 

SCDNR Fish Sampling 
On May 5, the SCDNR's Wildlife and Fisheries Division collected eight species of fish and conducted benzene analysis on 23 samples -- results did not find elevated levels.

SCDNR is awaiting histopathology results from the Southeastern Cooperative Fish Parasite and Disease Laboratory. Those results will be provided once received. 

The S.C. Department of Environmental Services (SCDES) continues to assess the health and water quality of Lake Greenwood through our routine sampling. Current water quality data do not indicate a concern for consuming fish or recreating in the lake.  

At this time, the cause(s) of the April fish kill has not been determined.  Early in the investigation a general precaution was made to avoid contact with the water in areas where the fish kill had occurred, however as previously stated, current water quality data do not indicate a concern for consuming fish or recreating in the lake.  

Key updates include:

  • Fish sampling  
    • Out of an abundance of caution, SCDES collected fish tissue samples as part of the April fish kill investigation. These samples have been sent to an independent lab to perform contaminant testing including a suite of metals, organochlorine pesticides, organophosphate pesticides, and organics. Results are pending. 
  • Water quality
    • SCDES maintains four routine monitoring locations in Lake Greenwood; water quality monitoring data for Lake Greenwood was provided in our May 15 update.  
    • Neither the routine monitoring data from these stationary monitoring sites nor the special water sampling conducted by the agency as part of the fish kill investigation indicate a water quality concern at this time. 
    • In response to the April fish kill, SCDES has been conducting more frequent sampling of routine ambient surface water sites in Lake Greenwood, and the agency is collecting regular vertical profiles to monitor the water column in the lower section of the lake. Monitoring data are normal. 
  • Reports of dead birds and wildlife
    • SCDNR is the state agency responsible for managing fish populations and other wildlife on and around the lake and can provide specific information about fish and wildlife investigations.  
    • SCDNR reported in the May 1 update that it had no indication of diseases or concerns among the fish it had sampled from the April fish kill.   
    • Duke Energy performed a vulture mortality investigation after reports of dead vultures near the Coronaca Transmission Line near Lake Greenwood. The report concluded that “a highly pathogenic avian influenza event as the likely cause.”

Please review previous fish kill updates, available at des.sc.gov/fishkills, for detailed data and information about various aspects of the investigation into the April fish kill.  

Additional information can be provided to SCDES using our online ReportIt! tool or contacting the agency at (803) 898-3432. 

The investigation into the fish kill that occurred between April 13-20 in areas of Lake Greenwood is ongoing. SCDES continues to perform sampling and assessments to try to identify the cause(s). 

At this time, the cause(s) of the fish kill has not been determined.  

Early in the investigation a general precaution was made to avoid contact with the water in areas where the fish kill had occurred, however, current water quality data do not indicate a concern for consuming fish or recreating in the lake. 

New key updates include:    

  • Additional site activities of nearby properties  
    SCDES provided maps, detailed summaries and findings of its site activities at nearby properties in the May 8 update. New information based on additional site investigations is available here, highlighted in yellow. Sampling data continue to indicate no impacts to Lake Greenwood from nearby properties.    

  • pH Data in Lake Greenwood 
    As provided earlier in the investigation SCDES identified no unusual water quality data for Lake Greenwood based on commonly measured water quality parameters, other than slightly elevated pH levels that were still within the “normal” range.   

    The state standard for pH in ambient freshwaters is 6.0-8.5, where values above and below this range constitute an exceedance of the standard. However, observations of pH in South Carolina lakes exceeding the upper range of pH (>8.5) are extremely common, particularly during the summer months when phytoplankton and aquatic plants are actively growing. 
     
    Over the last few years, pH values exceeding 8.5 have been common in Lake Greenwood generally between the months of May and September. The SCDES Ambient Water Quality Monitoring Program recorded pH values >8.5 in March and April 2026. Available here is the detailed survey of the lower lake conducted by SCDES on May 8, which documents a surface water pH range of 7.7-8.1. This range of surface water pH values is more consistent with typical spring conditions.  
     
    The feature of relatively high pH values in March and April has also been documented in large lakes across the state and is likely related to the ongoing drought in the US Southeast region. For context, the chart below displays surface water pH values in Lake Greenwood, Lake Murray, Lake Wateree, and Lake Hartwell since 2024. Measurements of pH follow a typical seasonal pattern of lower values during the winter months and higher values during the summer months, with frequent observations of pH >8.5. While pH values in this range area re slightly elevated for the months of March and April, these values are within the expected annual range for lakes in South Carolina.  

  • Metals Testing in Surface Water 
    SCDES conducts routine quarterly monitoring of metals in surface water across the state. Results of Lake Greenwood metals testing since 2020 are available here. Metals commonly associated with toxicity including cadmium, chromium, lead, mercury, nickel, copper, and zinc are extremely low in Lake Greenwood, generally below analytical method detection limit.  
     
    There are no metals-based water quality impairments for Lake Greenwood. There are also no mercury-based fish consumption advisories for Lake Greenwood. 

  • Video Alleging Chemically Burned Leaves  
    An SCDES botanist reviewed online video of alleged chemical-singed leaves. The expert’s opinion is the leaves were dying because they were submerged in water for a prolonged period of time. The leaves were starting to decompose and were not chemically burned.   

  • Cluster of Dead Vultures Below Lake Greenwood   
    SCDNR reported that the avian flu was the likely cause of death of the group of vultures identified below Lake Greenwood. 

  • SCDES's Statewide Ambient Surface Water Quality Monitoring Program 
    SCDES conducts its Ambient Surface Water Monitoring Program using two complementary approaches: a long‑term Base Network and a rotating Statistical Survey Network. Click here to read an overview of SCDES’S Ambient Surface Water Quality Monitoring Program. 

  • NPDES Program Regulating Point Source Discharges to Surface Waters 
    All point source discharges to surface waters are required to have an NPDES permit (National Pollutant Discharge Elimination System). The NPDES permit program was established under the Clean Water Act to prevent water pollution by regulating discharges from point sources, such as pipes, ditches, or other discrete conveyances, into waters of the United States. Click here to read more about how the NPDES program regulates point source discharge to surface waters 

The investigation into the cause(s) of the fish kill that occurred between April 13-20 in areas of Lake Greenwood is ongoing. The S.C. Department of Environmental Services (SCDES) continues to perform sampling and assessments to try to identify the cause(s).

SCDES’s Aquatic Science staff assessed the lake again today (May 8) by boat and observed no dead fish or dead snails. Surface water pH throughout the lower reaches of the lake ranged from 7.7 to 8.1, a considerable decrease from the elevated levels observed in April. 

At this time, the cause(s) of the fish kill has not been determined. 

Early in the investigation a general precaution was made to avoid contact with the water in areas where the fish kill had occurred, however, current water quality data do not indicate a concern for consuming fish or for recreating in the lake.

New key updates include:   

  • Fish sampling 
    SCDES collected live fish from Lake Greenwood on May 5-6. Filet and whole tissue largemouth bass, bluegill, flathead catfish, redear sunfish, and channel catfish samples will be analyzed for a comprehensive suite of metals, organochlorine pesticides, organophosphate pesticides, and polycyclic aromatic hydrocarbons (PAHs). An additional post-mortem sample will be analyzed for these parameters as well as polychlorinated biphenyl (PCBs), dioxins, and furans. Results are pending. 

  • Water quality 
    SCDES maintains four routine monitoring locations in Lake Greenwood; water quality monitoring data for Lake Greenwood is available here. Neither the routine monitoring data from these stationary monitoring sites nor the special water sampling conducted as part of the fish kill investigation indicate any elevated or concerning water quality readings. 

    • As provided previously, Lake Greenwood has two drinking water intakes for providing public drinking water (Greenwood Commissioners of Public Works and Laurens County Water and Sewer Authority), neither of which are located in areas where the fish kill has been observed. Both utilities have confirmed their drinking water is in compliance with all drinking water standards.    

  • Sediment sampling from nearby properties 
    A nearby property to where the fish kill was observed is known as the Ascend Site. The property owner entered into a Voluntary Cleanup Contract with the agency in 2016. A Voluntary Cleanup Contract (VCC) is an agreement between a company and SCDES in which the company agrees to assess and remediate a site that is known to be contaminated due to previous industrial operations on the property. A VCC requires the owner to conduct an investigation and perform environmental cleanup with SCDES oversight. The VCC determines the necessary actions for safely cleaning up the site. As part of the VCC for this site, the property is routinely monitored and has multiple protocols in place for preventing offsite impacts – this is standard for VCC sites throughout the state.

    • Neither the ongoing environmental monitoring occurring at this site as part of the VCC nor the investigative sampling recently conducted indicate any impact from the Ascend Site on Lake Greenwood. The investigative sampling results are available in this report.

    A parcel of land is located between the Ascend Site and Lake Greenwood, as indicated in the red-outlined area in this map (image below). A Phase I assessment report was conducted for this parcel and was submitted to SCDES in April 2026. This report indicates that the property did not have any environmental issues of concern.    


     

  • Site Activities Performed by SCDES
    Summaries of SCDES's site activities to investigate the cause(s) of the April fish kill are below:

  • Permitted wastewater dischargers 
    There are seven permitted wastewater dischargers within 20 miles directly up-gradient of the areas of the fish kill, as identified in this map. SCDES has been in contact with each facility and requested recent discharge monitoring data. Each facility reported effluent parameters within allowable limits, and no discharger stated to have had any process anomalies.

    On May 7, SCDES was made aware of a sanitary sewer overflow from one of these seven permitted wastewater dischargers — Ware Shoals Water and Sewer District — located approximately 20 miles up-gradient of the area where the fish kill occurred. The utility worked to quickly stop the SSO and issued a public notice. Based on the size of the SSO and the distance of the SSO from the area of the fish kill — approximately 20 miles — it’s highly unlikely this would have been a contributing factor to the April fish kill.   

As was previously provided, some of the most frequent causes of fish kills are oxygen depletion, excessive algal blooms and high water temperatures. None of these common causes appear to have been a contributing factor to this fish kill. 

Additional information can be provided to SCDES using our online ReportIt! tool (des.sc.gov/ReportIt) or contacting the agency at (803) 898-3432. 

State and local authorities continue to work together to investigate the recent fish kill in areas of Lake Greenwood in Greenwood County. The S.C. Department of Environmental Services (SCDES) and S.C. Department of Natural Resources (SCDNR) continue to perform assessments of Lake Greenwood; both agencies had staff assessing the lake by land and boat multiple days this week.  

At this time, the cause(s) of the fish kill has not been determined. Key updates include: 

  • SCDES reports no unusual water quality data based on commonly measured water quality parameters.  
  • The two drinking water intakes for providing public drinking water (Greenwood Commissioners of Public Works and Laurens County Water and Sewer Authority) are not located in areas where the fish kill has been observed, and both utilities have confirmed their drinking water is in compliance with all drinking water standards.   
  • SCDNR reports no indication of diseases or concerns among the fish sampled.
  • There have been no new reports of dead fish since April 20.  
  • Two properties near the lake are under investigation:
    • The first property is the former Monsanto/Ascend site where ongoing environmental cleanup and monitoring are occurring. No connection has been found between this property and the fish kill at this time.
    • Three empty drums were identified approximately 20 feet from the lake at a second property nearby on April 30. SCDES investigated the area near the empty drums on May 1 using advanced technology to determine whether any other drums were buried at the site. No buried drums were identified at this site. SCDES also screened the empty drums and the soil around the drums for organic vapors, and none were detected.
    • There is an ongoing investigation of additional sites based on reports from the public.      
  • Current water quality data does not indicate a concern for consuming fish. 

As was previously provided, some of the most frequent causes of fish kills are oxygen depletion, excessive algal blooms and high water temperatures. None of these common causes appear to have been a contributing factor to this fish kill. The property owner — GLH II, LLC — is fully cooperative.    

SCDES and SCDNR continue to investigate and will provide additional updates as new information becomes available. State officials encourage the public to follow trusted news sources for the most recent information. 

To report information related to this fish kill or any fish kill, contact SCDNR’s 24-hour reporting line at 1‑800‑922‑5431. 

SCDES, SCDNR and Greenwood County officials continue to work together to investigate the recent fish kill in an area of Lake Greenwood in Greenwood County.

Both state agencies continue to receive and review sample results as well as follow up on information provided by local residents in order to try to determine the cause.

Lake Greenwood has two drinking water intakes that supply public water systems: Greenwood Commissioners of Public Works and Laurens County Water and Sewer Authority. Neither of these drinking water intakes are located in areas where the fish kill has been observed. SCDES has been in contact with both facilities, and both report their finished water that is provided to customers is in compliance with all drinking water standards.

As was previously mentioned, some of the most frequent causes of fish kills are oxygen depletion, excessive algal blooms and high water temperatures. None of these common causes appear to have been a contributing factor to this fish kill.

State officials recommend people and pets refrain from contact with water in locations the fish kill has been observed, as referenced in this map.

This image is a labeled map of Lake Greenwood, showing various points of interest like Black Goat, Irvinies Landing, Lake Greenwood State Park, and Summersett Bay Rd. The map is provided by the South Carolina Department of Environmental Services.

Greenwood County Lake Management, SCDES and SCDNR will continue to investigate and provide additional updates as new information becomes available.

To report information related to this fish kill or any fish kill, contact SCDNR’s 24-hour reporting line at 1‑800‑922‑5431.

 

State and local authorities are working together to investigate a recent fish kill in an area of Lake Greenwood in Greenwood County. Greenwood County officials, the S.C. Department of Environmental Services (SCDES) and S.C. Department of Natural Resources (SCDNR) were notified of several dead fish in the Cross Hill area of Lake Greenwood on April 13 after receiving reports from the public. The agencies have been investigating, and at this time, the cause(s) of the fish kill has not been determined. 

Greenwood County’s Lake Inspector and Lake Manager responded promptly to assess the situation and reported their findings to SCDNR, the state agency responsible for managing fish populations on the lake, and SCDES, the state agency responsible for monitoring ambient water quality.

SCDNR has collected fish samples for analysis, and SCDES has conducted assessments and collected water samples in the affected area. Additionally, as part of ongoing investigations, SCDES is contacting facilities located upstream of the fish kill to determine whether any operational issues have occurred and to request their latest monitoring results.  

SCDNR reports the fish kill has impacted mixed species, including crappie, yellow perch, flathead catfish, striped bass and bluegill. The majority of reports related to the fish kill have been localized to the lower portion of the lake, below the lower train trestle. Isolated reports of single dead fish in other areas of the lake are likely not related to this incident.

Fish kills, which are instances when large numbers of fish die suddenly within a body of water, are relatively common and can be caused by various environmental, biological and human-related factors. Some of the most frequent causes of fish kills are oxygen depletion, excessive algal blooms and high water temperatures. None of these common causes have been observed at this time with this particular fish kill.  

Greenwood County Lake Management, SCDES and SCDNR will continue to investigate and provide additional updates as new information becomes available.

To report information related to this fish kill or any fish kill, contact SCDNR’s 24-hour reporting line at 1‑800‑922‑5431.

On April 17, 2026, SCDES staff collected water column data (i.e., vertical profiles) at nine locations across Lake Greenwood as part of the investigation into the cause of a fish kill. Sensor-based measurements were collected from the surface to the bottom of the lake and included pH, dissolved oxygen (DO), water temperature, specific conductivity and turbidity.

Data collected during this effort did not show evidence of water column-based features such as low DO or abnormally warm temperatures commonly associated with fish kills. The lake vertical profiles appeared typical for this time of year with normal temperature and oxygen levels throughout the water columns. The April 17 water column results are available here.