In my May 29 post, I suggested that new approaches are coming to address the tension between growing water demand for energy production, municipal and industrial needs, and preservation of natural resources. Mitigation through watershed restoration, using emerging ecosystem services markets, tops the list.
Conventional mitigation focused on local replacements, acre for acre, bucket for bucket. That makes intuitive sense when trying to address local impacts, except for the minor problem that local fixes don’t work very well. Often the mitigation sites are too small and close to developed areas so that the mitigation has only marginal ecological benefit. This is annoying to clients who are spending a lot of money on mitigation that their experts and the agencies know won’t accomplish much, and they sense that all they are doing is checking a box.
Watershed restoration approaches look at the whole system and put resources to where they do some real good. For example, if the issue is elevated discharge temperatures, one alternative is to install a mechanical chiller. That could work, but is expensive and energy intensive. A better alternative is to implement a riparian revegetation program throughout the watershed that provides multiple benefits over a longer time period than immediate cooling at point of impact. That’s the approach taken by Clean Water Services, the sewerage agency serving Washington County, Oregon. It was controversial at the time, but today is seen as innovative and forward looking. Kudos to CWS and the Oregon DEQ, which gave its approval!
Similarly, if the issue is depleted dissolved oxygen, common remedies include aeration or pumping in oxygen. That has the effect of addressing the impact where it can be readily measured, such as the discharge point below a dam or an anoxic portion of a reservoir. But this solution does not touch the more systemic problem of upstream nutrient loading. EPA and most states recognize this and have established water quality trading policies. These policies encourage transactions between upstream property owners and the party having the regulatory need for mitigation, in which the latter makes improvements on the former’s property to decrease nutrient rich runoff. Such measures can include conversion of agricultural drains to wetlands, fencing stream banks, or installation of more efficient irrigation systems.
Watershed restoration approaches are favored by regulatory agencies, academics and some environmental NGOs because they deliver long-term ecological uplift. The tradeoff is that realization of benefits can take a long time—even fast-growing trees like cottonwood take years to mature—and measuring compliance is problematic. But the potential reward makes it worth the risk.
Such measures as riparian planting, development of wetlands and returning meanders to straightened streams make good common sense, but the problem of metrics remains. Fortunately, there are smart people developing protocols for assigning credits for ecosystem services restoration that have gained agency acceptance. Take a look at the websites for The Freshwater Trust and the Willamette Partnership for more information.
That is not to say that watershed restoration methods for meeting regulatory requirements are free of controversy. They are not. But we’ve made real progress in advancing this approach and are confident it will become the norm in the not too distant future.