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A win for CSPA! City of Davis wastewater treatment plant must re-evaluate its discharges for chronic toxicity

By Bill Jennings, Chairman and Executive Director
July 25, 2008. On 21 July 2008, the State Board released a draft order regarding CSPA's appeal of the City of Davis National Pollutant Discharge Elimination System (NPDES) permit.  The Davis wastewater treatment facility discharges treated effluent into the Yolo Bypass.  The order is attached.

A hearing has been set for 10:00 a.m. on 2 September 2008.  Comments on the proposed order are due by noon on 20 August.   The City of Davis, Regional Board and CSPA's Bill Jennings are each allotted 10 minutes to comment orally.

The draft order remands the permit back to the Regional Board to establish copper and silver discharge limitations in the permit, to reevaluate EC (salt) limits and to include a narrative effluent limitation for chronic toxicity.  This is a significant victory as the State Board is clarifying that hardness values in the development of water quality limits in permits must be taken from receiving waters.  Hardness directly determines the toxicity of metals.  While CSPA does not completely agree with the specific selection of hardness values (which would have required additional limits for lead, nickel and zinc), they’re pretty close to what CSPA believed were necessary. 

The order does not address a major component of CSPA’s appeal that concerned groundwater pollution but says the Board will address those issues in a separate order, under its own motion.  The Davis facility has clearly polluted groundwater.

The most significant disagreements CSPA has with the draft order is its interpretation of the need for numeric limitations for chronic toxicity and the inadequate limit for acute toxicity in the original permit. 

Federal Regulations explicitly require a numeric limit for chronic toxicity where a “reasonable potential” exists.  For the last 5 or 6 years, the State Board has declined to uphold numeric limits by claiming that the Board is developing a new methodology.  In reality, the effort is at a standstill.  However, US EPA guidance has long recommended a specific procedure for determining numerical limits.  If CSPA cannot persuade the Board to include the EPA procedures, we may have to litigate this issue. 

The other significant disagreement concerns the Board’s rejection of CSPA's allegation that the acute toxicity limit in the permit illegally allows for lethality in receiving waters; something expressly prohibited by the Clean Water Act.  The Board has apparently confused the statistical variation of control samples in bioassays with variation in the actual testing of the effluent.  Their interpretation would allow up to 30% toxicity in a given sample.  Bill Jennings states, "This is a highly technical matter and I believe we’re right: as I developed our comments based upon advice and recommendations from a number of aquatic toxicologists who routinely conduct bioassays (both in and out of government).  And, I think I can convince them that we’re right."

In any case, this is a big victory in CSPA's first appeal of Central Valley Board permits that have been reviewed by the State Board.  The permit is remanded by the State Board to the Regional Board and the same issues have been raised in a number of CSPA's other appeals.