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The Obsolescence Of Watershed Planning

by Tom Holz

Basin planning has been performed in the northwest since the late 1960s. Its use peaked in the 1980s and its popularity diminished toward the end of the 1990s. Although the goals of comprehensive watershed planning have changed over the decades, since the 1980s (the heyday for such planning) the purpose has been primarily to preserve fish habitat, maintain channel stability, and ensure water quality in the receiving waters downstream of advancing urbanization.

Basin planning has relied on computer modeling of hydrology to provide us with a vision of changes that we could expect as a result of conversion of forest to urban purposes. We have further relied on fisheries biologists and ecologists to interpret the hydrologic forecasts to predict changes to habitat. And lastly, we have depended on end-of-pipe mitigation measures to protect streams from anticipated impacts.

There are many problems with basin planning as we have practiced it. The most salient are:

• Too little, too late. Basins are developed before any of the plans' recommendations can be implemented and thus the plans become moot.
• Leadership and "followership." Because basins cross many political boundaries, implementation of the plans commonly requires the cooperation of many jurisdictions. Cooperation, commitment, and funding have not been (nor are today) forthcoming from all the jurisdictions needed for implementation.
• We never really knew enough about linkages of forest hydrology and habitat protection to perform effective and adequate basin planning.
• The most serious of the flaws in the logic underlying basin planning is the assumption that we knew enough to have published an effective plan. The truth is that we have never had a firm grasp on the measures needed to ameliorate urbanization. Although we didn't know it until recently, solutions to the problems of development proposed in basin plans were never even close to adequate for avoiding destruction of a watershed.
• But, the good thing about all the money spent on watershed planning was the commensurate budget allocated for monitoring and documenting the health of streams. Although our recommendations for mitigation of development proved to be inadequate, the developments (and their impacts) themselves provided the data we needed to understand the situation and make good decisions. Impacts that we could not have predicted in advance, we have measured after the fact, and the principles needed to protect watersheds have been discovered through that effort.
• Monitoring by Karr, Booth, Horner, May, and others has documented the decline of watersheds following urbanization. Researchers have described measurable impacts to streams beginning at percentages of a watershed converted to impervious surfaces of two percent to five percent. Severe impacts are documented for impervious surface percentages between 10 percent and 20 percent. These researchers presented the results of 30 years of monitoring at "Salmon in the City," a conference held in May of 1998. Conference speakers provided us the principles for watershed preservation and the limits to watershed disturbance if we hope to preserve streams in the path of urbanization.
• These principles are:
  • Preserve 60 percent to 65 percent of the forest in a watershed.
  • Preserve intact, wide buffers along most of the length of streams down to the smallest tributaries.
  • Limit road crossings of streams.
  • Design and construct development so that "effective" impervious surface is held close to zero. -}
  • In none of the basin plans that the author has reviewed was this suite of "mitigation measures" even remotely hinted at. Instead, mitigation measures recommended were uniformly "end-of-pipe" approaches such as treatment and detention of runoff from projects that otherwise violated the principles above. Research now indicates that such measures will never provide the needed protection; the damage to a watershed from typical development is too great to recover from.
  • Looking back, it is clear that the tools we had to perform basin plans were inadequate to predict impacts and devise mitigation measures to prevent damage to watersheds. Looking forward, if we choose to spend our treasure on new watershed plans, experience tells us that we will learn nothing that we don't already know. If such future plans tell us that we can violate the principles that resulted from the Salmon in the City conference, what credibility will they have?
  • The obsolescence of watershed planning is mostly good news:
    • No new plans need be funded.
    • No citizens committees need be formed.
    • Implementation of the "Salmon in the City" principles does not depend on inter-jurisdictional cooperation or funding of regional projects.
    • Implementation needs no grant programs from state and federal agencies and no new programs or taxes at the local level.
    • Construction of (and endless maintenance of) ineffective stormwater facilities is no longer required. nstead, every jurisdiction with stream habitat to protect needs only to change its development regulations to forbid high-impact development strategies and permit only development that adheres to Salmon in the City principles. -} -}

      Restoration of existing damaged watersheds is equally simple. Jurisdictions need only require that redevelopment adhere to Salmon in the City principles. Over the course of time, as the basin redevelops, the forests will be restored, the existing stormwater collection system will be disconnected, and streams will respond positively.

      Simple adherence to Salmon in the City principles for development and redevelopment will achieve what basin plan recommendations could not. This approach frees us to redirect our resources to the more intractable problems of dwindling quality of life associated with urbanization, transportation needs, air quality, access to wilderness, parks, and a host of others. It is critical that we continue to monitor streams and watersheds, and refine our dearly won understanding of the principles for maintaining healthy watersheds, but land use plans are needed now, not basin plans.

      The knowledge that we have gained about the inviolable principles of watershed management was hard won and extremely costly. We paid for these principles in the currency of hundreds of damaged or destroyed watersheds and streams. Let us not waste this hard-earned knowledge. Let us not delay the implementation of these principles by yet more discredited and ineffective planning efforts.

      Tom Holz is an engineer with SCA Engineering in Lacey. He is the "guru" of low-impact development.

    
    

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