poisoning vegetation impacts delta fishery

Delta Posion | Whats In Your Fishery


w L ater

ast issue, we talked about the types, quantities,

frequencies and characteristics of the herbicides

being used to treat aquatic vegetation in the California Delta.


In this article, we are going to look at some of the data published by The California Department of Parks and Recreation – Division of Boating and Waterways regarding their monitoring results, impacts to aquatic species and water quality, and some concerns regarding the thoroughness of their monitoring design.

can be made. Unfortunately – no such studies are being conducted.

As part of the Floating Aquatic Vegetation Control Program and the Submersed Aquatic Vegetation Control Program, FAV and SAV, respectively, annual monitoring is conducted and results published by The California Department of Parks and Recreation (note at time of this writing, it is July 2019 and the latest published results are 2017).

Monitoring activities included recording impacts to beneficial uses*, federally listed species and their habitat. They monitor several water quality parameters and test for herbicide residues in or near treatment sites along with document changes in watercolor and odor and changes in

Fall 2019

When analyzing biological effects, it is common practice vegetative health within and around treatment areas.

to evaluate acute (immediate) and latent effects.

No systematic data collection into the affects to fish or

Acute effects would be exposure to toxic

other aquatic fauna, listed or not, is being conducted (or at

concentrations that would lead to immediate or near least published and released to public via their website) as

immediate mortality, whereas, latent would be

part of these monitoring efforts except via water quality (see

sub-lethal or lethal effects that take some


time to develop (i.e., delayed mortality,

No fish are being collected for tissue samples for the

reduced fecundity, decreased condition, etc.). presence of these pesticides nor are there any studies of

The fundamental elements critical to changes in fish abundance, distribution or diversity.

such analyses are sufficient sample size,

In fact, each of the annual reports directly states there

adequate controls, and study design to was no incidental take of threatened or endangered species;

allow for meaningful interpretation of

however, the data to support that claim is significantly

results from which actual conclusions


* Beneficial Uses: State Water Board adopted uniform list of beneficial uses, including definitions, to be applied throughout all regions of the State to determine if water quality objectives are being met. Beneficial uses are a general benchmark and are not usually site or species specific.


By Mike Gorman

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