Monthly Testing
Rivanna Water & Sewer Authority tests the Sugar Hollow Dam High Water Alert System monthly. The test is scheduled for the second Wednesday of each month at 10:00 AM. The next test is scheduled for February 11, 2026. Residents and visitors in the vicinity may hear the siren. During the test, there is no need to seek higher ground. The test will consist of several blasts, each lasting a few minutes. RWSA staff may be seen along Sugar Hollow Road during the test. They will be measuring the audible range of the new speaker system installed last month. The testing process is expected to finish by 11:00 AM. To receive reminder emails about the test, please complete the form above.
Background
Dam safety alert systems are important to provide early warnings in the unlikely event of potential dam failures or dangerous water releases. These systems monitor operating metrics to detect abnormalities, allowing for the appropriate activation of alarms. Effective alert systems help minimize the impact of floods, reduce economic losses, and ensure community resilience, making them a vital component of modern dam safety management.
In 2024, the Sugar Hollow Dam experienced a mechanical issue with its affixed rubber bladder, allowing excess water to flow downstream. The event prompted RWSA to reassess the dam’s redundancies related to the bladder and to explore potential alert systems. Improvements to the rubber bladder, its pneumatic piping systems, and control systems were completed in July 2025.
New Alert System
RWSA shifted its focus to procuring a new alarm system that alerts downstream residents to potential high-water events. In July 2025, RWSA installed a new siren at the dam. When energized, the siren emitted a 110-decibel whooping sound, and an auxiliary strobe light flashed. Watch the original siren in action here. On December 10, 2025, a new, more powerful siren was installed at the dam. This new system has four speakers, each rated at 130dB at 10 feet. Watch the new siren here.
Past Communications
12/11/2025 Additional Testing Planned for New Siren
9/8/2025 e-Newsletter: Sugar Hollow Dam High Water Alert System – What’s Next?
7/18/2025 Sugar Hollow High Water Alert System
Updates
12/11/2025 4:30 PM: Rivanna Water & Sewer Authority (RWSA) successfully installed an upgraded siren at the Sugar Hollow Dam on December 10, 2025. Minor testing was performed; however, additional testing is required. Staff will be on-site on December 12, 2025, from 9:00 AM to 10:00 AM to complete the testing. Residents and visitors in the area may hear the siren activate. During this period, there is no need to seek higher ground. The test will involve several blasts, each lasting only a few minutes. The new siren system has four speakers, each rated at 130dB at 10 feet. This is an upgrade from the older siren, which had only one speaker with a rating of 100dB at 10 feet. Watch a video of the new siren.
12/9/2025 3:52 PM: RWSA has canceled Wednesday’s test of the Sugar Hollow Dam High Water Alert System. Recent weather cause delays in installing the new siren. Construction crews will be on-site Wednesday removing the old siren and installing the new one. As a result, the alert system will be offline during the scheduled test. During installation and initial startup, residents might hear the siren activate briefly. If heard, there is no need to seek higher ground.
12/8/2025 10:09 AM: RWSA plans to test the Sugar Hollow Dam High Water Alert System on Wednesday, December 10, 2025, at 10:00 AM. Residents and visitors in the vicinity may hear the siren. During the test, there is no need to seek higher ground. The test will consist of several blasts that may last for a few minutes each. The testing process is expected to finish by 11:00 AM.
11/12/2025 11:08 AM: Rivanna Water & Sewer Authority has concluded today’s testing of the new Sugar Hollow Dam High Water Alert System. The system’s siren and strobe light energized as designed.
11/10/2025 1:44 PM: RWSA plans to test the Sugar Hollow Dam High Water Alert System on Wednesday, November 12, 2025, at 10:00 AM. Residents and visitors in the vicinity may hear the siren. During the test, there is no need to seek higher ground. The test will consist of several blasts that may last for a few minutes each. The testing process is expected to finish by 11:00 AM.
10/8/2025 10:26 AM: Rivanna Water & Sewer Authority has concluded today’s testing of the new Sugar Hollow Dam High Water Alert System. The system’s siren and strobe light energized as designed.
10/6/2025 12:21 PM: RWSA plans to test the Sugar Hollow Dam High Water Alert System on Wednesday, October 8, 2025, at 10:00 AM. Residents and visitors in the vicinity may hear the siren. During the test, there is no need to seek higher ground. The test will consist of several blasts that may last for a few minutes each. The testing process is expected to finish by 11:00 AM.
9/10/2025 10:45 AM: Rivanna Water & Sewer Authority has concluded today’s testing of the new Sugar Hollow Dam High Water Alert System. The system’s siren and strobe light energized as designed.
9/8/2025: RWSA plans to test the Sugar Hollow Dam High Water Alert System on Wednesday, September 10, 2025, at 10:00 AM. Residents and visitors in the vicinity may hear the siren. During the test, there is no need to seek higher ground. The test will consist of several blasts that may last for a few minutes each. The testing process is expected to finish by 11:00 AM.
8/13/2025 10:54 AM: Rivanna Water & Sewer Authority has concluded today’s testing of the new Sugar Hollow Dam High Water Alert System. The system’s siren and strobe light energized as designed.
8/11/2025 8:00 AM: RWSA plans to test the Sugar Hollow Dam High Water Alert System on Wednesday, August 13, at 10:00 AM. Residents and visitors in the vicinity may hear the siren. During the test, there is no need to seek higher ground. The test will consist of two separate 3-minute blasts. The testing process is expected to finish by 10:15 AM.
7/22/2025 4:30 PM: RWSA has concluded today’s testing of the new Sugar Hollow Dam High Water Alert System. The system’s siren and strobe light energized as designed. Staff will continue work on developing a regular testing program as well as installing downstream signage. Future updates will be shared as progress is made.
7/22/2025: Contractors and staff will be on-site this afternoon (7/22) testing the new system. Testing will occur between 2:00 PM and 4:00 PM. If you hear the siren, please do not panic. There’s no need for any immediate action. An update will be published once the testing process is complete.
7/18/2025: RWSA anticipates testing the new siren within the next week. Testing may occur as soon as Monday afternoon (July 21, 2025) but may extend later in the week. Communication will be sent immediately to local residents (and to those who have signed up for our e-newsletter) before each test. If you are in the vicinity and hear the siren, please do not panic. No immediate action is required. Upon a successful test, RWSA will install safety signage informing residents and visitors about the siren and what to do in the event the alarm sounds. These signs will be installed downstream of the Sugar Hollow Dam. A regular testing program will be implemented to ensure the alarm system operates properly. Additional details regarding the testing program will be forthcoming.