By CRAIG FREILICH
Following a dry summer, water flows in area rivers this August were at historic lows, after a season of high flows and flooding last year.
Flows on the Raquette, Grasse, and St. Regis rivers were well below the medians for the time of year.
And the U.S. Geological Survey says St. Lawrence County had been enduring a “severe hydrologic drought” until heavy rain a week ago.
The St. Regis River was running at what is believed to be its lowest flow on record at the dam near Parishville last week, at about 44 cubic feet per second, according to Parishville resident Fred Wilhelm. That is less than half the mean rate of about 110 cubic feet per second for this time of year, he said.
Other examples of this year’s unusually low flows in area rivers, as shown in the graph of readings on Aug. 25, are the 100 cfs flow on the Grasse at Chase Mills, compared with an eight-year median of 400 cfs and a reading of 700 cfs a year before; and 180 cfs on the Raquette at Piercefield, compared with the 103-year median of 500 cfs and 600 cfs a year ago on Aug. 25.
If the 44 cfs figure is confirmed for the St. Regis, that will have been 1 cfs lower than the 45 cfs of the former lowest discharges on Sept. 6, 1999, and Aug. 16, 2001, according to the USGS gauge near the bridge on Jones Road four miles above Parishville. The gauge has been measuring the river since 1958.
By contrast, the Aug. 25, 2011 reading at Parishville was bookmarked by flows of 400 cfs a week earlier and 950 cfs a week later.
After the heavy rainfall Tuesday night, Sept. 4, the discharge unofficially reached 750 cfs the following day, only slightly lower than the highest discharges of this past spring. But that rainfall put St. Lawrence County out of the “severe hydrologic drought” category.
On Sept. 4, the U.S. Geologic Survey had St. Lawrence County in "severe hydrologic drought," indicating that estimated seven-day average streamflow was at or below the fifth percentile for that day, based on at least 30 years of records and current flow measurements around the county.
But by Sept. 6, after the heavy rain, St. Lawrence County was no longer in severe drought, according to the daily USGS map.
Many recreational boaters are preparing to pull their craft out of the water earlier than usual due to low water levels. Some have complained that the lower water is making some places that are usually accessible to them now out of bounds for fear of grounding.
There is a similar concern along the St. Lawrence Seaway.
Spokeswoman for the Seaway Vicki Garcia said there “have been no adjustments to navigation” since Seaway Notice 10 – 2012 was issued in June. That notice warned that low water levels had required a reduction in the maximum allowable draft of some vessels in even then in the Montreal to Lake Ontario section.
No further measures have been taken since then, but “water levels are continuously monitored and navigation notices will be issued as conditions warrant,’ Garcia said.
Brookfield Renewable Power, which runs several hydroelectric generation stations along the Raquette and other rivers, watches streamflows closely as a regular part of their power generation program.
This year, they have had to operate at a power production level that is lower than usual.
“After experiencing record water levels and even flooding last year, flows in the Raquette River have been well below normal this year, which has been reflected in hydropower generation,” said Julie Smith-Galvin of Brookfield.
“These variations are a normal part of the hydrology cycle, and accordingly, we manage our operations using long-term averages based on over 100 years of flow data,” she said.
“As in the past, we would expect river conditions and hydropower production to revert back to normal levels in due course.”
Last year was a record-setting year for some flows in the region. The record flow on the Raquette at Piercefield was 10,400 cubic feet per second on May 1 last year.
The highest flow in August this year there was about 700 cfs.