How quickly you see water flowing down the Upper Delaware - or experience as you paddle along - is not entirely at the whim of the weather.

(Editor's Note: This is a corrected version. The first version misidentified the bay where the Delaware River leads, and the salt line is monitored by the DRBC.)

NARROWSBURG, NY - How quickly you see water flowing down the Upper Delaware - or experience as you paddle along - is not entirely at the whim of the weather.

How much water is released into the Upper Delaware from the New York City reservoirs upstream has been dictated since 1954 by a decree issued by the U.S. Supreme Court. Gauging those releases is the Office of the Delaware River Master, using the United States Geological Survey (USGS) measuring station at Milford Beach just below Milford, PA and known as the Montague Gauge.

Uncertainties, however, can frustrate the best intended regulated flows.

Upper Delaware Council (UDC) in Narrowsburg has watched closely and gave opinions on the impacts of the 1954 Supreme Court Decree since the UDC was founded 31 years ago. Staff from the Office of the Delaware River Master offered an overview to the UDC, April 4. On hand were Robert R. Mason Jr., Delaware River Master; Kendra Russell, Deputy Delaware River Master; and Vin Difrenna, Staff Hydrologist.

Montague Gauge

Established by the U.S. Supreme Court Decree, the Office of the Delaware River Master has its goal to keep 1,750 cubic feet per second (cfs) flowing past the Montague Gauge. The Office has authority to direct the New York City Department of Environmental Protection (NYC DEP) to make releases from the Cannonsville, Pepacton and Neversink reservoirs to help maintain that goal.

In addition, the River Master must take into account water let go from Lake Wallenpaupack by the power company, Brookfield Renewable into the Lackawaxen River, and from Rio Reservoir on Mongaup River, and also hydrological data measuring storm runoff and precipitation.

The 1954 Supreme Court Decree, as summarized by Mason, arose out of an adjudication between the State of New Jersey and the State of New York and the City of New York. The City has built its reservoir system in the Delaware River Basin. The Supreme Court decided to petition the uses of the water in the Delaware. The Court assigned to the City of New York its rights to draw a maximum of 800 gallons per day (gpd) out of the River. The City also was required to release compensating waters in order to maintain a target flow downstream.

They created the River Master position, and assigned him oversight of the Decree’s provisions that relate to diversions, flows and releases from those reservoirs.

Included is the charge given the River Master to observe and maintain records, and make reports to the Supreme Court.

Daily computations

Daily computations are made by the River Master staff to determine what the flows would have been absent any release by New York City. Staff then projects that forward four days, and the City is then instructed to supply enough water to make up the difference between the targeted flow and the computed flow.

The River Master communicates with the City of New York and the four states that comprise the principals of the 1954 Decree and have a vital stake in the amount of water coursing down the Delaware River: the States of New York, Pennsylvania, New Jersey and Delaware.

Russell, the Deputy River Master, noted that Decree is a “living document.” Also dictating what the Office of the Delaware River Master does is the most current (2017) Flexible Flow Management Plan (FFMP) developed by the Delaware River Basin Commission.

Five year plan

In 2018 the River Master Office developed a five year plan to try and match priorities with the FFMP. The priorities are:

Improve daily directed releases and with updated technology, make those release requirements as accurate as possible.

Streamline and improve communication. Data is released to the public by the River Master online.

Produce an annual report by 2020.

Bring scientific context to meetings to help others with basin river management. The River Master works closely with U.S.G.S.

Engage groups within the U.S.G.S. that do water monitoring, to ensure that data the groups produce is useful.

Power plants factor in

The hydroelectric plants at Wallenpaupack and Mongaup must be taken into account in maintaining the target flow at Montague. Russell noted, however, that the River Master does not have authority over release of water from these sources into the tributaries that add to the Upper Delaware’s flow, because they are not part of the 1954 Decree.

The power companies provide the River Master with information on how much they plan to generate and how much water they actually release.

Data must be studied several days before and several days in the future.

“The New York City reservoirs are several days away,” Russell said. “We need to tell them how much water to release several days in advance so when all that water comes down to Montague, we meet the flow target.”

Here’s how long it takes water spilled or released, to reach the Montague Gauge downstream:

Cannonsville Reservoir on the West Branch, above Hancock: 60 hours

Pepacton Reservoir, on the East Branch: 48 hours

Neversink Reservoir: 33 hours

Wallenpaupack: 16 hours

Rio: 8 hours.

The Wallenpaupack and Rio power plants are closer to Montague Gauge than the NYC reservoirs. Russell said there is not enough time for the River Master Office to make up for the water released by the power plants. “If those forecasts change, for whatever reason on their part…we don’t find out about the changes until after we directed the releases from the New York City reservoirs,” Russell said.

Along with weather forecasts given the River Master by the National Weather Service, the power plant releases are a point of uncertainty, she said.

“We try and use the best data at the time that we have to make the call, but we have to make the directed release three days in advance for the New York City waters to get there at the time we need them,” she said.

Mason stated that Brookfield Renewable, the current owner of the Wallenpaupack plant, has been good at communicating and working with the River Master Office. He said communication has improved over the years. Rio has also been consistently providing data. The River Master has met with officials of both power companies, to explain why the data is needed.

The River Master Office has about a day to reduce uncertainties if the Weather Service forecast changes.

Trenton: 3000 cfs

New York City also does conservation water releases regardless of the River Keeper Office, to deal with drought, and the Trenton, NJ gauge target farther downstream. The targeted flow at Trenton is 3,000 cfs.  Water releases required by the FFMP also are separate from the River Keeper’s mandated target level.

The River Master Office has a goal of meeting the 1750 cfs target, but to not exceed it. Russell quipped that as far as she knows the Supreme Court has never called them up and chastised them for going over the target.

Steve Tambini, representing the DRBC, said that they have a flow target at Trenton to deal with flow management in the Lower Basin, including holding back the salt line from the Delaware Bay.  “Water flows downstream,” Tambini reminded, so if the target was not met at Montague, it impacts the management of flows in the Lower Basin.

Sometimes being over the Montague target is out of the Delaware River Keeper’s control, such as when it is raining hard, Russell said. 2018 was a very rainy year, which caused the targeted flow to be missed. She said that when they are under the Montague flow target, there is greater concern.

For more information about the Office of the Delaware River Keeper and daily flow data, visit https://webapps.usgs.gov/odrm/.