Wrightsville's Fall Schedule:
Weekdays, 11AM to 7PM
(Services Available by Appointment)
Weekends, 10AM to 7PM
(Full Services Available)
LAST DAY FOR 2024 WILL BE SEPTEMBER 30TH
Updated 09/12/2024
Weekdays, 11AM to 7PM
(Services Available by Appointment)
Weekends, 10AM to 7PM
(Full Services Available)
LAST DAY FOR 2024 WILL BE SEPTEMBER 30TH
Updated 09/12/2024
Some Dam Flood Details
The Wrightsville Dam was completed in October, 1935.
In 1961 they completed additions to the height to increase the capacity, and replaced the original stone spillway with the current concrete "ogee" weir. This was done so the dam could contain the maximum probable rain event, as calculated long before the impact of Climate Change on the volume of water in present day and future precipitation events.
In 1985 the water level was raised to enable Electricity to be generated via a single, single stage turbine. The Hydro operation is owned and operated by the Washington Electric Coop.
Washington Electric Coop generously contributes to the Park's budget to help provide quality and affordable recreation facilities. Thank you very much WEC!
In 1961 they completed additions to the height to increase the capacity, and replaced the original stone spillway with the current concrete "ogee" weir. This was done so the dam could contain the maximum probable rain event, as calculated long before the impact of Climate Change on the volume of water in present day and future precipitation events.
In 1985 the water level was raised to enable Electricity to be generated via a single, single stage turbine. The Hydro operation is owned and operated by the Washington Electric Coop.
Washington Electric Coop generously contributes to the Park's budget to help provide quality and affordable recreation facilities. Thank you very much WEC!
Click this link to go to the USGS's Wrightsville & Northbranch graphs of each gage. They are updated hourly..
The Reservoir's gage's graph shows the current surface elevation from sea level,
The gage located a bit below the dam can show the flow volume, in cubic feet per second, or the gage height in feet.
The Reservoir's gage's graph shows the current surface elevation from sea level,
The gage located a bit below the dam can show the flow volume, in cubic feet per second, or the gage height in feet.
The majority of the time the surface level is at 634 feet (above sea level).
This current record setting peak reached 684.15 feet at 10 PM on the Tuesday night of July 11th 2023.
This current record setting peak reached 684.15 feet at 10 PM on the Tuesday night of July 11th 2023.
As of Wednesday July 12th at 9pm the surface elevation was 682.82 feet.It dropped by 1.33 feet in 23 hours.
> 680.71 ft as of Thursday, 6/13 at 9:45pm, and dropping. It dropped by 2.11 ft in 24 hours.
Historicaly the water level will drop by 1.33 feet to 2 feet per day, and the rate increases, until it's dropping by around 4 feet daily at 660 feet and then even faster per day until it's back to the level of the sand beach again.
> 680.71 ft as of Thursday, 6/13 at 9:45pm, and dropping. It dropped by 2.11 ft in 24 hours.
Historicaly the water level will drop by 1.33 feet to 2 feet per day, and the rate increases, until it's dropping by around 4 feet daily at 660 feet and then even faster per day until it's back to the level of the sand beach again.
It will likely be 10 days from today (7/13/23) until the Park Manager can get to the parking area level to assess the building & shelters. Please don't go into the park until we have had time to assess and plan.
Please be aware that our plan will include a few dates on which we'll be seeking volunteer assistance with TBD tasks.
I will create an email registration link ASAP. So please check back for that and other updates in a day or so.
Please be aware that our plan will include a few dates on which we'll be seeking volunteer assistance with TBD tasks.
I will create an email registration link ASAP. So please check back for that and other updates in a day or so.
The graph of the flow rate (in cubic feet per second) of the North branch of the Winooski, as measured a short distance below the Wrightsville Dam is at this link.
That maximum flow rate of about 980 cubic feet per second is the absolute maximum that the Primary Spillway can release through its 5 foot square conduit that runs 645 ft through the dam.
The Reservoir maximum retention capacity is roughly 4.9 billion gallons.
There is no "controllable" way to release more than ~980 cubic feet per second. The dam works on fixed flow rates via the Primary Spillway.
The dam is designed for the Secondary Spillway to be the release method.
If the water is to overflow the 150ft long Secondary Spillway then that volume of water would be added to the ~980cu ft/s.
During the rain event on Sunday night, the water surface elevation was rising by about 1.35 feet per hour. So that 1.35 feet per hour of water that up to the top of the Secondary Spillway had been retained behind the dam, above it the 1.35 ft/hr of water would have headed downstream at the same rate of all the water entering the Wrightsville Reservoir per second. Water in would equal water out, so at that point the Dam's total discharge rate is up completely determined by the rainfall at that moment.
That scenario has never happened at the Wrightsville Dam, but that is in fact how it is designed to retain water, discharge a maximum rate that won't overwhelm the North Branch or Downtown Montpelier. On Monday night we came within about a foot from it over flowing the Secondary Spillway.
Given the rainfall over the previous 32 hours we were only about 2 hours of additional steady rain from having a much worse experience downstream.
That maximum flow rate of about 980 cubic feet per second is the absolute maximum that the Primary Spillway can release through its 5 foot square conduit that runs 645 ft through the dam.
The Reservoir maximum retention capacity is roughly 4.9 billion gallons.
There is no "controllable" way to release more than ~980 cubic feet per second. The dam works on fixed flow rates via the Primary Spillway.
The dam is designed for the Secondary Spillway to be the release method.
If the water is to overflow the 150ft long Secondary Spillway then that volume of water would be added to the ~980cu ft/s.
During the rain event on Sunday night, the water surface elevation was rising by about 1.35 feet per hour. So that 1.35 feet per hour of water that up to the top of the Secondary Spillway had been retained behind the dam, above it the 1.35 ft/hr of water would have headed downstream at the same rate of all the water entering the Wrightsville Reservoir per second. Water in would equal water out, so at that point the Dam's total discharge rate is up completely determined by the rainfall at that moment.
That scenario has never happened at the Wrightsville Dam, but that is in fact how it is designed to retain water, discharge a maximum rate that won't overwhelm the North Branch or Downtown Montpelier. On Monday night we came within about a foot from it over flowing the Secondary Spillway.
Given the rainfall over the previous 32 hours we were only about 2 hours of additional steady rain from having a much worse experience downstream.
While the Surface level is dropping, and is down over a foot we still need to be aware that the ground & streams within Wrightsville's 69 square mile watershed are completely saturated and full, so any significant rainfall can make the level stop declining and even resume increasing in a matter of an hour or two, depending on the rainfall rate & duration.
Remember that no more than ~980cu ft/s can squeeze through that 5' conduit, that's it.
Remember that no more than ~980cu ft/s can squeeze through that 5' conduit, that's it.
There are potential alterations to the Dam & Hydro operations that might allow the dam to prepare for the next big rain event by using existing dam infrastructure to be able to control the release of additional water above the 980cu ft/s. Alterations require significant research, planning, and capital investment, which requires a great demand and or justification to make change. This event, along with the shorter weather forecast definitely provide justification, it's up to residents, Industry, and our elected leaders to create the demand.
