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Washington State Department of Ecology Clarifies Water Rights Ambiguity Associated with RWH…Is Colorado Next?

By Kurt Unger, ARCSA Northwest Regional Representative

To the delight of the green building community and many other Washingtonians throughout the state, the Department of Ecology issued a policy statement issued on October 12th clarifying that water rights are not required for either the use of or the on-site storage of rainwater collected by a rooftop system or a guzzler (Guzzlers are devices used to catch and store rainwater and dew to provide wildlife or livestock with drinking water.)

Under the department’s policy, the on-site storage and/or beneficial use of rooftop or guzzler collected rainwater is not subject to the permit process of RCW 90.03. But if and when the department determines that rooftop or guzzler rainwater harvesting (RWH) systems are likely to negatively affect instream values or existing water rights, local restrictions may be set in place to govern subsequent new systems. To qualify as rooftop collected rainwater, the roof collecting the rainwater must be part of a fixed structure above the ground with a primary purpose other than the collection of rainwater for beneficial use.

To those not familiar with the issue, the response to reading the above paragraphs is likely “Why in the heck was Ecology requiring water rights for rooftop RWH in the first place?” The answer is, unfortunately, a long and sordid tale. Nearly all states west of the Mississippi River follow one form or another of what is commonly known as the Prior Appropriation Doctrine. The underlying tenant of this water law doctrine is first in time, first in right. That is, the first person to use a certain quantity of water for what’s called beneficial use (pretty much everything except wasteful use) has a senior water right. The right doesn’t actually accrue until after the individual files the appropriate permitting paperwork and the agency in charge approves the application – Ecology is that agency in Washington State. Not all applications are of course approved because water is a finite resource. Subsequent approved applications have what’s called a junior water right. When water supply is tight (during a drought, for example) or in basins where water is seemingly perennially tight (such as in the Yakima Basin in Washington), the most junior water right holders are told they must stop using water so that the more senior water right holders get their full water allotment. This priority-based system has caused some issues with RWH in Washington and some western states, notably Colorado and Utah – two states that are actively attempting to regulate and enforce strict legal interpretations about the use of rooftop rainwater requiring a water right.

Previous interpretations of the broad language of Washington’s 1917 surface water code, RCW 90.03, found that the use of undefined phrases describing water limited the department’s ability to nuance what sort of uses are not subject to the water right permit process. The Legislature took notice of the issue in 2002 and tried to provide a fix. Unfortunately, they were unsuccessful. To their credit, they kept trying every year thereafter, but the issue proved too challenging for a resolution. As the years passed, the situation was becoming more and more untenable. RWH projects were getting pushed into the permit application backlog (currently just under 7,000 and rising). Ecology tried regional permits but couldn’t permit RWH fast enough. The result? Everyone was just doing RWH anyway and Ecology was losing credibility fast. Last year, Ecology undertook a renewed, detailed look at relevant water law to see if another viable interpretation exists. Happily, we found that another reasonable interpretation does indeed exist and that’s where we are today. Hopefully, Washington’s practical policy will show other western states that are struggling with this issue, notably Colorado, that there is a rational path forward on this issue. As renowned water law professor David Getches notes in his book, Water Law in a Nutshell, “Obviously, not all water on earth is capable of management by governments.”

In the case of rooftop collected rainwater, not only not capable of management, but not desired except where the cumulative impact of many, many very large RWH systems creates a situation where even more large RWH in that particular area could actually negatively affect instream values or existing water rights. Ecology doesn’t think that’s likely because of the very small nature of most systems and more importantly, because of the retiming and stormwater management benefits that RWH systems provide. In places where water is the tightest in Washington State (the Yakima Basin), RWH is highly unlikely to catch on because of the minimal amount of precipitation that basin receives (7-8 inches) – you’d need a heck of a large roof to catch a very minimal amount of rain.

On the west side of the Cascades, RWH is decentralized stormwater management in urban areas. In rural areas where RWH could actually provide a sole source of potable water, RWH typically provides aquifer recharge benefits. How is that? Well, such homes are almost always not served by a sewer system and thus the home discharges water used indoors underground via a septic system. True, a portion of that rainwater, if not captured and stored, would have otherwise recharged the aquifer. But most of that precipitation would have either quickly runoff the site or evapotranspirated (evaporated and/or been used by grass/shrubs/trees). When used non-consumptively indoors, RWH systems take all the precipitation captured and release it underground into the septic system, where it is not nearly as susceptible to evapotranspiration. Even with some consumptive use from summer irrigation – there won’t be much due to the lack of precipitation in the summer - the net effect is there’s more water in the system than before. That’s not the case with a permit exempt well. Wells enable far more irrigation potential and wells are actually impairing water rights and negatively affecting instream flows. From a water conservation/efficiency standpoint, RWH is very much preferable to a permit exempt well. Add to that, because climate change is predicted to bring a reduced snowpack that melts off earlier in Washington State, RWH systems can be a decentralized climate change adaptation tool. Harvest away Washingtonians, as we need all the stormwater and climate change adaptation tools we can find.

Kurt Unger is a hydrologist, attorney and public interest advocate. Kurt works on policy development for the Washington State Department of Ecology’s Water Resources Program. He is also is an adjunct professor at the Evergreen State College in Olympia, Washington. When not trying to bring sanity to water law, Kurt enjoys recreating on/in water, particularly the fluffy, partially frozen and warm, salty kind.

Related Links

State Guidelines and Regulations
ARCSA Website



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