Mongaup River System Lake Levels and Rio Operation Forecast

Current lake levels in the Mongaup River System are:

Rio Unit Operations Forecast/Estimate:

Discussion as of 5/23/2025:

As the weather warms and rain returns, all reservoirs are beginning to refill.  Toronto Reservoir is expected to refill near elevation of 1200 over the course of spring.  Swinging Bridge Reservoir and Cliff Lake may fill rapidly in the coming week based on predicted significant rainfall. They will be near full by Memorial Day and targeting back down to 1068 by July 1. Mongaup Falls Reservoir elevation will remain between 930 and 931. Rio Reservoir elevation will remain between 813.5 and 815 for fish spawning which started May 15 and runs through June 30. 

Toronto Reservoir Drawdown:

The Toronto dam, which impounds Black Lake Creek to create Toronto Reservoir, is part of the Swinging Bridge Hydroelectric Project (FERC Project No. 10482). The Swinging Bridge FERC license is held by Eagle Creek Hydro Power, LLC, Eagle Creek Water Resources, LLC and Eagle Creek Land Resources, LLC (collectively, “EC Mongaup”). Safety is EC Mongaup’s number one priority. EC Mongaup views its ownership and operation of the Mongaup hydroelectric system as a privilege and it deeply respects the public safety responsibilities that come with that privilege.

EC Mongaup regularly monitors the Toronto dam in accordance with FERC dam safety regulations. Recent monitoring data contained some anomalies that warrant closer evaluation. In response to these anomalies, EC Mongaup has increased the frequency of its monitoring efforts and is further investigating other pertinent data to better understand the anomalies and determine appropriate next steps. As part of this increased monitoring, FERC’s Division of Dam Safety and Inspections directed EC Mongaup to “lower the pond in a controlled manner, by about 0.5 ft per day”.

EC Mongaup began the drawdown on May 12, 2023. Based on the engineering analysis performed and the recommendations of FERC and our independent consultant, EC Mongaup has agreed to hold Toronto Reservoir no higher than elevation 1,200 ft until remediation of the dam is complete. For reference, the reservoir’s typical recreational level is approximately 1215 feet. EC Mongaup has convened an independent Board of Consultants (BOC) to oversee the ongoing investigations and remediation of the dam.

The public should be aware of the following:

• EC Mongaup has closed the public boat launches at Toronto Reservoir, but the public access areas remain open.

Throughout the drawdown, EC Mongaup will provide regular updates to stakeholders and will collaborate with local, state, and federal authorities to minimize the potential environmental and recreational impacts of the lower reservoir level.

Email Notification List:

If you are interested in receiving a notification by email when there is a significant change in the elevations forecast, you can sign up for our email notification list here: Swinging Bridge/Toronto Shoreline Management Notification Signup

Disclaimer:

Lake level information and forecasts provided by EC Mongaup are for informational purposes only. While EC Mongaup makes efforts to provide accurate information, errors may occur. All lake level information and forecasts are subject to change based on weather conditions, equipment availability, and power generation. While EC Mongaup attempts to forecast lake levels and anticipated power generation, it does not commit to operating to those forecasts, and reservoir elevations and generation schedules may deviate from the forecast provided without any notice on this website or elsewhere. EC Mongaup makes no representation or warranty, expressed or implied, about the accuracy, reliability, or suitability of data or forecast information on this website for any particular purpose.