T’was the night of April 1, and all through the water not a creature was stirring, not even a fish! The consultants were recovering, all snug in their beds, while visions of happy clients danced in th…
T’was the night of April 1, and all through the water not a creature was stirring, not even a fish! The consultants were recovering, all snug in their beds, while visions of happy clients danced in their heads! EEM reports were submitted to the Regional Authorization Officer (RAO) at last, in hopes that Cycle Three would not come fast!
I am talking about Cycle Two Environmental Effects Monitoring reports (weighing about 1 to 2 kg each!), which mills were required to submit to Environment Canada for an April 1, 2000, deadline. These comprehensive studies describe biological effects of mill effluents on receiving waters. Based on conclusions of studies I was involved with and discussions with other consultants, an informal and unofficial look at some of the findings follows. Keep in mind that these results are for a small number of mills only.
First and foremost, the environmental improvements after Cycle One EEMs are substantial and very encouraging due to the benefits of installing secondary treatment facilities. Effluent sublethal effects (on growth and reproduction of aquatic organisms) have been reduced significantly so that in many cases tests have often shown no sublethal effects [1] to two out of the three species tested (i.e., fish, crustaceans and algae). The consequence of this is that the size of the zone of potential effects in the receiving environment is small. For example, it could be estimated that under low river flow conditions, the zone of potential effects (based on cycle two sublethal toxicity data) would extend 50 m downstream from a mill outfall. Before secondary treatment, this same zone would have extended several kilometers downstream.
Studies of the benthic communities (i.e. organisms living on the bottom of rivers, lakes or oceans) also showed significant improvements and reductions in the downstream zones of effect. This is sometimes seen by a lack of statistical differences when comparing the abundance of organisms or the number of taxa (i.e. diversity) between upstream and downstream sampling stations. Overall, pollution-sensitive species (certain types of insects and larvae) are re-colonizing areas immediately downstream of mill outfalls.
The results of the fish survey at a few mills have shown that fish diversity and biomass downstream from the mills were not affected. The sites showed no effects on fecundity or gonad weight (no reproductive impairment based on these two measurements). These findings are in concordance with several studies conducted to date, which suggest that effluents from modernized mills with good secondary treatment are unlikely to alter reproduction of fish until effluent concentrations reach 20% or greater [2]. These concentrations are rarely seen in receiving waters downstream from Canadian mills. One site showed higher fecundity (more eggs per female fish) and an increase in gonad weight downstream suggesting a more productive fish community than upstream. There were no effluent effects on condition factor (i.e. plumpness of the fish), which is often an indication of good fish health and/or the presence of ample food resources. Some potentially negative results such as increased fish liver size were also found downstream of some sites and these results still need to be explained. Overall, results showed comparable fish communities upstream and downstream from the mills.
Cycle Two EEM results will undoubtedly raise many questions as to the cause of certain effects on fish and whether or not these are due to mill effluent or cumulative impacts. There can often be several inputs to waterways and a gradually decreasing water quality as one moves downstream. Other sources include agriculture, storm and sanitary sewers, other industry and municipalities. This overall effect on water quality can have a negative biological effect on fish that inhabit the area downstream from the mill.
The US has approached the above problem by conducting watershed studies that are intended to protect entire watersheds. This involves the development of total maximum daily loads (TMDLs) for all key users (dischargers) on the system, including municipalities, small businesses, farmers, and industry. This approach makes the most sense for environmental protection since our overall objective should be to protect entire aquatic ecosystems, not just portions that lie downstream from mills. In fact, think of all the environmental benefits the following would have:
Mandatory 20 m vegetated buffer zones (e.g. row of trees) between all farmland and river banks, including the implementation of proper management strategies for manure and pesticides, and for controlling runoff.
Mandatory effluent treatment for small businesses.
Cycle Two EEMs have also provided much useful information for improving the design of future studies. For example, the EEM Technical Guidance Manual recommends a transformation [3] of the fisheries data collected prior to statistical analysis of the data. However, Barry Zajdlik, a bio-statistician who has worked on EEMs, recommends that the requirement for such data transformations always be tested. The results can be very different in both cases (transformed vs non-transformed data) and can lead to a different environmental interpretation of mill effluent effects that may not be in the mill’s favor. In some cases, data transformations and other guidance provided are applicable to working with large fish but not small-bodied fish that were used in many Cycle Two studies.
For the fish survey Environment Canada currently considers a difference of 20 to 30% in a measured parameter betweenreference and effluent-exposed sites as potentially relevant from an environmental point of view (less than 20% could be due to natural variability).
The Ontario Ministry of Environment is currently considering a similar approach for evaluating benthic study results [4], based on European studies. It suggests that specific criteria, such as 20 to 30% difference, be used to explain significant differences in benthic communities due to pollution. The point is that statistical difference may not be significant if it is low. It may simply represent natural variability in the watershed. We should consider these new ideas for future EEM study design.
There is a need for industry to advertise the significant environmental improvements that Cycle Two has shown. Most “interested parties” (e.g. employees, the community, the public, shareholders, clients, etc) would feel the same way if the information is communicated to them.
REFERENCES
1. No sublethal effects defined as IC25>100% effluent. The IC25 is the effluent concentration that causes a 25% inhibition of a measured effect (i.e. growth or reproduction).
2. RIEBEL, P. and BORTON, D. Aquatic Ecosystem Protection. Chapter In: Environmental Control for the Pulp and Paper Industry (A. Springer, ed.). To be published in May-June 2000.
3. Logarithmic transformation
4. KRANTZBERG, G. et al. 1996. SEDS: Setting environmental decisions for sediment. Prepared for the EOA Remedial Action Plan Steering Committee, OMOE.
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