The Stream Doctor

July 19th, 2004

Email YOUR Questions directly to the Stream Doctor. This is your opportunity to get an experts professional opinion on anything stream related.

Q. Hatcheries and hatchery programs have come under fire lately for numerous reasons, but especially the issues of gene dilution and costs associated with stocking fish in marginal waters for questionable recreational value. Very little discussion has been given to the pollutional effects of hatchery effluent. In some situations the presence of a hatchery on a stream can have serious consequences. In central PA there is a limestone spring creek that has lost its native brook trout due to hatchery effluent. The gravel interstitial water in redds becomes hypoxic (DO values~4.5ppm) after 40-60 days. Benthos in the upper 3 mi. below the hatchery consists mainly of pollution tolerant forms, especially isopods. We found only two references to failure of reproduction below hatcheries (both European). Are you aware of the potential of hatchery effluent to cause these kinds of problems? References?

A. I'm sure there are places where hatchery effluents can degrade water quality downstream, but I would also guess that problems are largely site specific depending on the characteristics of the effluent and the receiving stream. One of the ongoing plans to enhance anadromous salmonid returns to the Yakima River system in WA was to add a series of rearing ponds in the drainage to supplement natural reproduction. I was asked to determine if the effluents would have any effect on the primary production (algal growth and oxygen production) in the receiving streams. I examined this by determining how much nitrogen and phosphorus would be added from each pond, whether this would change the existing ratio of nitrogen and phosphorus in the stream, and predicting whether the change in the nutrient regime would be significantly enough to enhance algal production. In no case did the added effluents change the nutrient regime significantly. Now, this is just one situation that I was involved with, and I was not concerned with benthic fauna. I'm not sure whether this was published by the state or not; I retired and left the lab and have lost track of what happened to the report. I could find out if you want me to pursue it; contact me at

If you have a question, please feel free to contact me.
~ C. E. (Bert) Cushing, aka Streamdoctor
105 W. Cherokee Dr.
Estes Park, CO 80517
Phone: 970-577-1584

The 'Stream Doctor' is a retired professional stream ecologist and author, now living in the West and spending way too much time fly-fishing. You are invited to submit questions relating to anything stream related directly to him for use in this Q & A Feature at

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