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The recent implementation of the Flexible Flow Management Plan (FFMP) and its TMPDMP release schedule for the Cannonsville Reservoir

Posted on June 05 2008

The recent implementation of the Flexible Flow Management Plan (FFMP) and its TMPDMP release schedule for the Cannonsville Reservoir that the DRBC put into effect last fall has put the world class wild trout fishery on the upper Delaware, and particularly the lower West Branch and Main Stem Delaware in great danger! The hot weather forecast to arrive here this weekend, and likely to prevail for most of the summer, will elevate water temperatures into the seventies downstream from Balls Eddy. These water temperatures are lethal for the wild trout populations and very damaging to the businesses that depend on the fishing industry!

We at Friends of the Upper Delaware River are deeply disturbed by the way the River is being managed with what appears to be indifference for the cold water fishery. In the first half of April, spillage from Cannonsville was supplemented by heavy releases resulting in West Branch flows of 3,000-5,000 cfs. Thus, water was being wasted and early season fishing made impossible – particularly for wading fishermen.

Then on April 16, Cannonsville releases were reduced from 1,500 cfs to a mere 251 cfs – the yo-yo effect in the extreme. The resulting sharp reduction in flow (with the reservoir full or nearly full) was very disruptive to aquatic life. We found vast numbers of dead aquatic insects (mayfly nymphs) left high and dry on exposed gravel beds, including some in the middle of the River, potentially damaging spawning beds and insect populations while floating recreational and guide boats became impossible during a time of year when the West Branch normally flows 800-1,000 cfs and the spring hatching and fishing are beginning to take off.

Subsequently, reservoir in-flows must have exceeded releases because spillage began again. On April 20, the authorities increased releases, again to 1,500 cfs which increased the overall flow to over 1700 cfs. Then on April 23, they dropped releases to a shockingly low 80 cfs, driving West Branch flows far below the seasonally normal of 800-1,000 cfs (more yo-yo releases). The release from the Pepacton Reservoir was even lower, showing 54 cfs on the Downsville gauge. Thus, regulatory actions threatened the fisheries on the West Branch, East Branch and Main Stem all at a time when the reservoirs were virtually full and the trout season was beginning to build momentum.

Luckily, the unseasonably cold weather in late April and May has given the trout fishery a welcome reprieve but all this is about to end! With the current low release of 260cfs at Cannonsville, and no possibility of Montague triggered releases, and a weather forecast of 80-90F degrees, we can expect the water day time temperatures in the lower West Branch to be in the seventies and the Main Stem between Hancock and Lordville to reach the mid to high seventies – lethal for trout and virtually certain to preclude day time hatching and fishing! This is all happening at a time when all the upper Delaware reservoirs are 95% full.

The recent USGS studies on the river and the SEF group working in conjunction with the DRBC have repeatedly warned about the yo-yo releases and the damage they cause to the fishery. There is now a broad consensus that the FFMP’s THPDMP release program is harmful to the entire ecosystem as it now stands. In the past few weeks a major change on the River’s ecosystem has already been detected. The record low flows on the West Branch as prescribed by the FFMP in April and May have created slow, shallow water conditions throughout the system accelerating algae growth (the normal flow during this period is between 700-1200cfs) causing problems for the fisherman who can hardly make a cast without getting the pesky algae fibers on their hooks – a real nuisance. Also and importantly, it is reasonable to assume that this growth will have an impact on the aquatic insect population which is renowned on this river system and is mandatory for the continued growth of the wild trout fishery. This development must be looked into by the DRBC!

FFMP low releases were predicated on the NYC usage of 800 mgd, but in fact NYC uses less than 600 mgd. If the OASIS model runs were based on a more realistic 600 mgd diversion instead of an 800 mgd figure, even with optimum releases from all three reservoirs based on the IFIM values contained in the recent USGS report, we would see fewer drought days, significant flood mitigation, and NO threat to any water supply to NYC or the downstream states.

The Trout Unlimited Coalition and the flood groups have gone on record calling the FFMP’s THDTMP release schedule a disaster, as has the Pennsylvania Fish and Boat Commission. SEF has called for graduated releases to avoid the yo-yo effect and the NJDEP has said that there is normally plenty of water in the system to accommodate all the River’s many users as well as the fishery.

To avoid damage to the fishery and the ecology and to shield the local economies from the decline in recreational revenues that will surely result from the FFMP as presently stuructured, the regulators must be persuaded to allow temporary minimum releases of 600 cfs from Cannonsville and 125 cfs from Pepacton until proper modifications to the FFMP can be applied. Also the yo-yo releases must stop.

Vice President, Communications
(570) 807-5123

Sandy Bing, Treasurer

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