As I mentioned in another post, yes they are still releasing from the res. This is a big contributor to the higher water level and cooler temp on the SBR below Clinton. Not sure why they're releasing but my guess would be to maintain a 'void' in the res capacity to capture heavy storm runoff in the event of a major and potentially flooding rain event. At present the res is only about 2 feet below full, not a major deal. You can track it here...
http://waterdata.usgs.gov/nj/nwis/uv...65,00060,62614
You can track the release rates here...
http://waterdata.usgs.gov/nj/nwis/uv...65,00060,62614
As for the drawdown last fall and in most years late summer, this is first and foremost a water supply reservoir. When the precip rates drop and the mainstem Raritan threatens to fall below a certain level they begin releasing to maintain the level in the mainstem as many cities and towns use the river for their municipal water supply.
The reason that SRR is drawn down before RVR is simple economics, RVR is pumped storage which costs money in the form of electric to keep full whereas SRR is filled by runoff. In very bad drought years you'll often see SRR drawn down over 20 feet before they begin releasing from RVR.
Also, they have 2 outlets to release from RVR to supply the Raritan mainstem. Most know about the pumping station on the SBR below Clinton, but they can also release into the S. Br. Rockaway Crk. They (the NJ Water Supply Auth) maintain a steady release flow into Rockaway as it is since during the construction of the res they cut off the headwaters of the creek and as a result were mandated to maintain the steady release. If you see a spike in the flow rate here...
http://waterdata.usgs.gov/nj/nwis/uv...65,00060,62614 without any rain event to cause it you can be assured it's due to a release from RVR.
The same maintenance flow release holds true for Prescott Brk on the SW side of the res. however this one only gets a steady maintenance release, it's never used as a supplemental flow source for the SBR.
