Owens Valley Committee » Blog Archive » Vegetation Management

Vegetation Management

The Inyo-LA Long Term Water Agreement (LTWA) doesn’t guarantee DWP a minimum volume of pumping, nor does it set a pumping ceiling.  DWP is allowed to pump every drop it can, provided it complies with its obligation to “avoid” certain impacts to vegetation relative to conditions as measured by DWP in the mid-1980’s (aka “baseline conditions”).

How is it determined whether pumping is in compliance with the impact avoidance requirement?  This has been a subject of much contention between DWP and Inyo County and is at the heart of the failure of the LTWA.

One way to meet the legal requirement to avoid impacts is to manage pumping according to the “on/off” protocol.  This protocol is based on a feedback loop.  Decisions about pumping any given set of wells are based on measurements of vegetation cover and soil water availability at an associated monitoring site.  The details are complicated, (and skewed toward leaving wells on) but the basic concept is comparing measured soil water with estimated vegetation water requirements. If soil water exceeds the estimated vegetation water requirements, wells go on.  If not, wells go off.  Wells may go on again only after soil moisture increases to the amount required by vegetation at the time the wells went off – not by the amount required to sustain baseline vegetation conditions. Pumping is directly linked to conditions of wellfield vegetation, a dramatic change from previous protocols (during the 19 years of litigation leading to the LTWA) in which pumping was controlled in relation to ranges of annual runoff.

Unfortunately, the on/off protocol has proven ineffective at meeting its goal avoiding impacts to vegetation relative to baseline (1984-1987) conditions.  DWP claims – correctly – that it complies with the on/off protocol, yet vegetation and water table monitoring data show clearly that precisely the impacts LTWA management is intended to avoid are, in fact, occurring in some areas.  See the groundwater management discussion for more information about the failure of the on/off protocol.

Another way to determine if impacts are being avoided is by sampling vegetation throughout wellfields (instead of just at the 33 permanent monitoring sites used for the on/off determinations) and comparing current conditions with those of the baseline period.  The Technical Appendix to the LTWA includes a protocol for random sampling of vegetation parcels to allow for comparison with baseline conditions.  If current conditions have not declined relative to baseline, and/or trends suggest conditions are stable it is evidence impacts are being avoided.

Inyo County began implementing the random sampling protocol on behalf of the Technical Group in 1991. By the early 2000’s results showed vegetation conditions in certain parcels were consistently below those measured in the baseline period and that the changes were precisely those DWP had predicted as responses to prolonged water table drawdowns.  Furthermore, test well data showed water tables under these parcels had usually been drawn-down below the grass rooting zone since the late 1980’s, when the LTWA was being negotiated.

Inyo County took these monitoring data as evidence that current management was not consistent with the goal of impact avoidance and challenged DWP’s 2000 annual pumping program.  Inyo argued proposed pumping was too high and cited vegetation monitoring data as well as depth-to-water data to support its complaint.  In its response, DWP disavowed the entire LTWA vegetation parcel monitoring protocol (which had been used by Inyo).  It treated Inyo’s complaint as a failed attempt to seek mitigation and acknowledged no obligation to avoid impacts at all.  The arbitrators refused to make a ruling and sent the case back to the Technical Group.  Inyo County then appealed to Inyo Superior Court and the judge, too, sent the case back to the Technical Group.  Inyo did not pursue the complaint further.

In 2001 Inyo again challenged DWP’s annual pumping program.  Inyo again cited vegetation monitoring and depth-to-water data to support its complaint.  DWP again made no reference to any obligation to avoid impacts and disputed Inyo’s right to challenge its pumping program.  This time the arbitrator, in effect, split the difference between DWP’s proposed pumping and Inyo’s alternative.  Legal documents for both the 2000 and 2001 disputes are no longer online, but are available at the Inyo County Water Department.

DWP then undertook a campaign to defend its management in the court of public opinion.  In 2004 DWP general manager Gerry Gewe explained, “Some of the environmental interests up in Owens Valley would suggest that we have substantially changed the habitat up there. Our scientists would say it’s within the spectrum of what would change with the normal variation. I don’t know that anyone will ever come up with a clearly definable answer to that…”  The self-serving nature of this statement is unmistakable.  If “no one can ever come up with” the difference between natural variation and pumping impacts, DWP can never be shown to have created any further pumping impacts and be liable for mitigation.  In signing the LTWA DWP implicitly admitted its pumping had, previously, created significant impacts; this belies the assertion it is impossible to distinguish pumping impacts from “normal variation”.

In 2005 DWP consultants produced a set of three reports presented to the public as disinterested analysis (“The Science Behind Managing Natural Resources in Owens Valley”) but better described as advocacy. The consultants also gave public presentations, which culminated in OVC sponsoring a public meeting to rebut the misinformation of the DWP consultants.  At the OVC meeting, DWP’s Brian Tillemans asserted that DWP’s 1984-87 vegetation inventory, written into the Water Agreement (Technical Appendix) as the baseline against which vegetation change would be measured, was not suitable for statistical analysis and that it was not even “a scientific, precise study or documentation of vegetation.”  Needless to say, if baseline data are not reliable, DWP can never be shown to have created new pumping impacts.  However, don’t doubt DWP’s good intentions! At the same meeting DWP manager Gene Coufal explained, “[impact] avoidance, we do take it seriously…we just don’t know where avoidance is.”

By 2007, conditions at one parcel (Blackrock 94) were so bad, according to monitoring data gathered under the LTWA protocol, that the Bristlecone Chapter of the California Native Plant Society wrote a formal letter requesting reduction of pumping so significant impacts would be “avoided”.  This led (several years later) for Inyo to initiate a formal challenge to the 2011 pumping program, which eventually morphed into two separate disputes, not over modifying management to “avoid impacts” but over whether mitigation after-the-fact was needed.  In 2014 DWP and Inyo finally reached a settlement in which pumping has been slightly curtailed in the area of Blackrock 94.

As part of the Blackrock 94 settlement, the Ecological Society of America was awarded a contract to provide facilitation and a panel of experts to help resolve disagreements about vegetation monitoring.

As of 2015, over 20 years after the LTWA was signed, there is no agreement between DWP and Inyo on how to monitor vegetation, nor is there agreement on how monitoring data should be compared with baseline data to identify significant impacts. One lesson is clear: framing of LTWA vegetation management goals in the negative (“avoid certain described changes…” was a mistake.  With no affirmative criteria for defining success it has not been difficult for DWP to render the impact avoidance goal meaningless.

— Daniel Pritchett