The hatches are much heavier below the hatchery, mainly because of the
fertility of the water there. That is why the fish tend to hold in that
section, and why most of them are in such good shape. Prior to the
construction of settling ponds to collect most of the solid waste, raw
waste from the hatchery used to flow directly into the river. At that
time, there wasn't much activity at the outflow, but there were some
amazing sulphur hatches further downstream. There were many evenings
when there were so many naturals on the water, that it was nearly
useless to fish. So in answer to your question, the hatchery does add
some "pollution" to the river, but it increases the fertility, and
thus, the insect activity. Hatches above the outflow tend to be sparse
and brief, except in the outflow from below the Quabbin dam where it
feeds the Y Pool.

Next spring, say late April to mid May, try fishing below the Secret
Spot in the Cady Lane area. If the water is at a normal level there
should be some Hendrickson activity, and a few really nice holdover
browns will be feeding there along with the native brookies and a few
stockies