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Hartwell Lake Level Restrictions Overview

To help protect surrounding communities, the U.S. Army Corps of Engineers’ (USACE) Savannah District will maintain lake level restrictions at Hartwell Lake until a long-term engineering solution is designed and built to resolve risks associated with seepage deterioration identified at Clemson Lower Diversion Dam Saddle Dike. There is no immediate danger to the public. However, during a recent USACE Dam Safety Program evaluation, several required actions were identified, including the lake level restrictions, which are necessary until a permanent solution can be developed and implemented. The temporary restriction is intended to reduce stress on the Saddle Dike by limiting how high Hartwell Lake can rise during periods of heavy rainfall. For additional information, please visit the News Releases page.

Clemson Saddle Dike - Conceptual Cross-Section

This is a cross section of Clemson Saddle Dike to conceptionally show the seepage path that is occurring. Clemson Saddle Dike seepage issues require us to implement Interim Risk Reduction Measures to mitigate safety issues until a permanent solution can be developed and implemented.

USACE has observed areas where lake water is seeping through and under parts of the dam, specifically the Clemson Lower Diversion Dam Saddle Dike, causing material to erode and reduce its strength. Over time, this can create paths where water continues to pass under the dam, taking materials with it. Eventually, this can weaken the dam, causing parts of it to slope or slough. In severe conditions, this can cause the dam to fail and allow water to flow freely behind the structures. This is considered a dam emergency.

These issues have been observed since 2015 but were not progressing fast enough to pose immediate danger. However, more recent data, observations during recent significant storms, such as Hurricane Helene, and detailed analyses demonstrate the issue is worsening. The Clemson Saddle Dike will eventually fail if no actions are implemented to mitigate and repair it.

Immediate Solutions

Interim risk Reduction Measure for Clemson Saddle Dike

U.S. Army Corps of Engineers’ (USACE) Savannah District will maintain lake level restrictions at Hartwell Lake until a long-term engineering solution is designed and built to resolve risks associated with seepage deterioration identified at Clemson Lower Diversion Dam Saddle Dike. USACE will keep water levels below a maximum level of 662 feet mean sea level (MSL) at Hartwell Lake. To provide enough flood storage, the lake's normal operating (full) level, known as the guide curve, will be lowered to elevation 656 feet MSL year-round.

Interim Risk Reduction Measures Hartwell Lake Level Restriction: A lake level restriction is a safety measure where we limit how high the water level in Hartwell Lake is allowed to rise. Lowering the lake level reduces the amount of pressure on the dike which slows erosion and keeps the current condition stable. Enhanced Monitoring and Readiness: USACE is increasing on-site inspections and monitoring while emergency management teams are updating inundation maps, reviewing Emergency Action Plans (EAPs), and conducting tabletop exercises with Clemson University and county emergency personnel. Environment and Legal Compliance: USACE is completing an Emergency Environmental Assessment (EA) under the National Environmental Policy Act (NEPA) to study impacts on recreation, local businesses, and biological resources.

The Permanent Fix USACE will initiate a formal Dam Safety Modification Study to evaluate permanent, long-term engineering solutions to stabalize the Saddle Dike. Timeline Dam Safety Modification Studies typically take up to two years to complete Design, funding approval, and physical construction can take five years or more

Consequence of Inaction

The Clemson Saddle Dike will eventually fail if no actions are implemented to mitigate or repair. A breach would flood the low-lying areas behind it, including portions of Clemson University infrastructure, significantly impact the university's sewage treatment plant and operations, and require a massive draw-down of Hartwell Lake to facilitate emergency repairs.

Timeline Tracker

Public and Recreational Impacts

Current Reality (Drought): The basin is currently experiencing Level 2 drought conditions, meaning Hartwell Lake is already sitting roughly 8 feet below its normal guide curve. Since the water level is already below 656 feet Mean Sea Level (MSL), recreational users will see no immediate change to boat ramp or swim beach availability as a result of the lake level restriction.

Future Reality (Post-Drought): Once drought conditions end, the lake will not return to its historical 660-foot summer full lake level. Instead, it will be held at the 656-foot restriction level.

Dock Permits and Property Values

Water Safety

600 MSL: Previous full lake level 656 MSL: New full lake level

Frequently Asked Questions

Q1. What is the issue with the Clemson Lower Diversion Dam Saddle Dike?
Answer: During detailed safety evaluations and monitoring, engineers identified water seeping through and under the Clemson Lower Diversion Dam Saddle Dike (Saddle Dike) through a network of seepage paths. Over time, water seeping through a soil structure can slowly wash away fine soil particles, carving out tiny tunnels in a process called "piping" or backward erosion. If left unaddressed, this process weakens the dike and can eventually cause the structure to give way.

Q2. Is there an immediate danger of the Clemson Saddle Dike breaking?
Answer: No, there is no immediate threat of failure, and we have not activated the dam's emergency action plan. However, detailed technical evaluations indicate that the erosion is worsening. If we do not act proactively to relieve the stress on the structure now, it could fail in the coming years. We are acting today to prevent a future emergency.

Q3. What is a "Saddle Dike" and why is it important to Clemson University?
Answer: A saddle dike is a secondary protective barrier built in low elevation spots along the edge of a reservoir to keep the water from spilling out. The Clemson Protective Works—which include two diversion dams and this downstream Clemson Saddle Dike—were built before Hartwell Lake was filled. Their primary purpose is to divert, or reroute, the Seneca River and prevent Hartwell Lake from flooding Clemson University properties.

Q4. What would happen if the Clemson Saddle Dike failed?
Answer: If the Saddle Dike failed, water from Hartwell Lake would flood low-lying areas behind it, directly flooding parts of Clemson University, including local infrastructure and the sewage treatment plant. It would cause an extended shutdown of the university, endanger human lives, and force USACE to immediately and severely draw down Hartwell Lake to perform emergency repairs.

Q5. What is a “lake level restriction" and how does it fix the problem?
Answer: A lake level restriction is a safety measure where we limit how high the water level in Hartwell Lake is allowed to rise. By lowering the lake level, we reduce the depth of the water standing against the Clemson Saddle Dike. This reduces the water pressure (hydrostatic pressure) pushing through the structure, which slows down or stops the internal seepage and erosion, keeping the dike stable.

Q6. What will the water level of Hartwell Lake look like under this restriction?
Answer: The Guide Curve: Typically, Hartwell Lake's target water level (guide curve) varies seasonally between 660 feet above mean sea level (MSL) in the summer and 656 feet in the winter. Under the interim lake level restriction, the guide curve is lowered to a flat 656 feet MSL year-round. Maximum Limit: We will manage the dam releases to prevent the lake from rising above 662 feet MSL (3 feet lower than the normal maximum flood lake level of 665 feet) to avoid placing high water pressure back on the Saddle Dike. If rain events push the lake above 656 feet, we will actively work to release water and pull the lake back down safely.

Q7. We are in a severe drought right now. How does that affect this restriction?
Answer: Because the region is currently experiencing a Level 2 drought, the water level at Hartwell Lake is already well below the new 656-foot restriction level. Therefore, you will not see an immediate, sudden drop in water levels as a result of this announcement. However, when the drought ends and heavy rains return, the lake will be held at the 656-foot target.


Q8. How long will this lake level restriction remain in place?
Answer: This restriction is an interim safety measure and is expected to remain in place for multiple years. Resolving this issue permanently requires a formal Dam Safety Modification Study followed by federal funding allocation, engineering design, and physical construction. A Dam Safety Modification Study typically takes up to two years to complete, while the subsequent design, funding approval, and physical construction timeframe is currently unknown, yet it could take five 5-10 years or more.

Q9. How will this affect my boat dock, boat ramps, and lake recreation?
Answer:

  • Docks: Because the target lake level is set to 656 feet year-round, adjacent property owners with shallow-water docks will experience dry conditions more frequently than in past non-drought years.
  • Boat Ramps: Many boat ramps will remain functional at 656 feet, but access will be reduced compared to normal high-water years. Some shallow ramps may close. We continue to maintain an up-to-date list of open and closed boat ramps on our Hartwell public website.
  • Swim Beaches: Designated swim beaches generally become unusable when lake levels drop below 657 feet. This means that under the 656-foot restriction, designated swim areas will remain closed or dry.

Q10. Is the lake still safe for boating and swimming?
Answer: Yes, the lake remains open for recreation, but boaters and swimmers must exercise extreme caution. Lower water levels expose submerged trees, sandbars, rock formations, and other navigation hazards that are usually underwater. Swimmers need to be aware of underwater obstructions and sudden drop offs while swimming outside designated areas. Always wear a life jacket, watch your depth finder, navigate slowly in unfamiliar areas, and never swim alone.

Q11. Will this lake level restriction impact our local drinking water supply?
Answer: No. We have evaluated municipal water intakes around Hartwell Lake. The lake level restriction level of 656 feet MSL keeps water levels well within the safe operational limits for local water supply systems, ensuring clean and reliable drinking water continues to reach local homes and businesses.

Q12. How does this impact hydropower generation?
Answer: While a lower lake level slightly reduces the total water volume and "head" pressure available to spin the turbines, USACE has structured the restriction to minimize impacts to hydropower. We are working closely with the Southeastern Power Administration (SEPA) and local utility partners to balance power generation needs with our primary safety requirements.

Q13. What should I do if a dam-related emergency occurs?
Answer: In the highly unlikely event of a dam emergency, local county emergency management officials (in Anderson, Pickens, and Oconee counties) and Clemson University Emergency Management are the lead authorities for notifying the public, directing evacuations, and specifying safe travel routes.

  • Sign up for your county's emergency alert system immediately. Familiarize yourself with local evacuation routes.
  • Learn more about flood safety and emergency planning at www.ready.gov/flood

Q14. What are the next steps for USACE, and how can the public stay informed?
Answer:

  • Next Steps: We are finalizing our environmental evaluations under the National Environmental Policy Act (NEPA) and will soon release a draft Environmental Assessment (EA) for public review and comment. We are also initiating the formal Dam Safety Modification Study to evaluate permanent engineering fixes.
  • Stay Informed: We are hosting virtual public information sessions in September 2026 and in-person sessions regarding the Environmental Assessment in November 2026.
  • Inquiries: You can track updates on our official project webpage, follow the Savannah District Facebook page, or email your questions directly to our dedicated inbox at Cesas-HartwellPoolRestriction@usace.army.mil.

 

Map of Clemson Dams

Clemson Map

Location and Purpose
The Clemson Upper and Lower Diversion Dams and Saddle Dike are located on the South Carolina side of Hartwell Lake adjacent to Clemson University. The dams reduce flood risks to the surrounding area, including Clemson University. These three (3) features were built before filling Hartwell Lake with the primary purpose of rerouting Seneca River to prevent flooding the surrounding area, including Clemson University properties.

Background Information

Hartwell Lake and Clemson Dams
The Hartwell Dam is built across the Savannah River on the Georgia/South Carolina border in the counties of Hart, Georgia and Anderson, South Carolina. The project also includes two diversion dams and a saddle dike on the South Carolina side of Hartwell Lake adjacent to Clemson University. These three features, sometimes called the Clemson Protective Works, were built before filling Hartwell Lake with the primary purpose of rerouting Seneca River to prevent flooding Clemson University properties. The Clemson Upper and Lower Diversion Dams were constructed across two sections of the old Seneca River channel. The Clemson Lower Diversion Dam Saddle Dike (Saddle Dike), which fills in a section of natural ground that was lower in elevation, is located south-east of the Lower Diversion Dam and runs from the Clemson University sewage treatment plant to the edge of the Clemson University Walker Golf Course. Water that falls in this area collects at lower elevations and is removed using USACE operated pumps that move water into Hartwell Lake so it can be held or released downstream through Hartwell Dam.

Historical Concerns
Erosion and water seeping through and under these features has been a reoccurring challenge. While repairs were successfully executed at the Upper and Lower Diversion Dams in the 1980s through the installation of cutoff walls - underground barriers built to block and control water movement - no such remediation was performed at the Saddle Dike. It is highly probable that seepage was not apparent there during that period; however, the exact reasoning remains unconfirmed. In 2015, active seepage was discovered within the Saddle Dike's foundation, exiting into a heavily wooded marsh area. This issue may have gone unnoticed for decades until its detection during an academic field inspection. Over time, water passing through or under parts of a dam can weaken it and cause it to give way, resulting in water flowing freely in areas behind the diversion dams and saddle dike. USACE has been monitoring the erosion and seepage concerns at the Clemson Lower Diversion Dam Saddle Dike since 2015. Recent detailed evaluations of this area identified the need for immediate actions to intervene to improve safety of the structure and work to  ensure conditions do not worsen.

Page Contents

  • Overview
  • Restriction Information
  • Frequently Asked Questions
  • Map and Background Information