11 Sep 2014

Does fixing a mistake make it worse?

EC writes from Florida:
One of the big questions staring me in the face is... as we reach the limits of sustainable use without “significant harm” to the environment and reuse more and more wastewater, what happens to the systems that have adapted to the volume of discharge provided by our waste stream outfalls?

We have looked at many issues to determine if there is extra available water in our basins, but the amount of “freeboard” available for additional human use may be equivalent to the volume projected to go into reuse -- purple pipe systems here -- in the future.

Reuse is fantastic for farmers recapturing and reusing fertilizer runoff, cities looking for less regulated water sources for esthetic irrigation, and water quality improvements in general. It is terrible for salinity intrusion up rivers with lower discharge volumes, groundwater recharge areas fighting salinity intrusion, hydroperiods in flat wetlands, migratory species looking for a critical water depth, and other water volume dependent issues.

Have you looked at that?

Also variability in the demand for water reuse is a big issue. Spray fields used to help discharge extra water exceeding reuse storage volume, almost always occurs on rainy days or after the soils are saturated. That is when lawns don’t need to be watered and spray fields are least effective at handling the runoff. It seems to be when reuse water managers run the spray field pumps 24-7. What is your experience with the expense of reuse water storage?
As all of you know, I am not a scientist, and therefore unqualified to comment on the size of the impacts from these changes in use, but I wrote this back:
I agree with your general points, that (1) "efficiency" may leave nothing for nature (eg, the Jordan River) and (2) human centric changes may tip systems into collapse.

But those dangers are often ignored by humans. My "end of abundance" thesis is that we've exceeded limits that we've been able to ignore for ages.

What are our choices, now that we're seeing the impacts of our behavior? We can either step back and rethink our habits or drive ahead and off the cliff.

It seems you've described the manifestations of failure to reform. The question is whether policy "leaders" will act on those bad outcomes
Can any scientists comment on the these issues? Can any policy wonks give examples of where science feedback is driving policy reform?

(The EU's Water Framework Directive is an attempt to improve environmental water quality and quantity, but it's top-down and resisted by many national governments.)

1 comment:

John D. said...

I can think of a few examples on doing more with wastewater and what happens to systems dependent on effluent. This may not answer any questions but it’s some food for thought.
Southwestern US outfall discharging to an arroyo type stream that has seasonal flow, I think it also had a very low year round flow. I worked on the permitting the increased discharge of this facility many years ago (so the details are foggy). Discharge to the stream was allowed at x% of the stream flow. To increase discharge to the stream the facility had to increase its storage capacity to hold effluent during the dry months and discharge during high stream flows. The storage ponds were certainly lined with impermeable material so any loss not attributed to discharge was through evaporation. So, no real ability in the design and permitting of this plant to allow for habitat or ground water benefits. In situations like this added habitat at the discharge created by the additional water is usually home to non-native species that are not adapted to the seasonal fluctuations of the natural system. IMHO, loss of that added habitat (if the plant began purple piping all its effluent) would not be a huge loss from the point of view of the natural ecosystem.
The Arcata Marsh and Wildlife Sanctuary: one of the first constructed wetlands to treat combined sewer wastewater plant effluent. In this example, there’s no water scarcity, but an abundance of water in the rain forests of Northern California. So, perhaps not a great example of a system that could ever loose it’s effluent source, but if it did? The system would transition from mostly fresh to somewhat saline as water from the bay tidally pushed further into the marsh. There I would expect to see a shift in the ecotone.
When envisioning the future I think the stormwater managers of the Pacific Northwest have the right idea: “keep it on site, slow it down, minimize impervious surfaces”. I think this can also translate to reuse of municipal wastewater. These onsite reuse ideas are beginning to drive policy reform through the creation of local policies that permit domestic greywater reuse (in many places this is still not legal or permitable). All this reuse both on the large regional and small local scales will need to address the increasing concentrations of petrochemicals, pyrethroids, hormones, nutrients, and other modern nasties that are the elephant in the room. Now we’ve arrived at the bridge christened “the environmental economics of our collective chemical dependency”, and it’s high time we cross that bridge and mitigate the true costs.

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