WSP05172

• File Number: 8220.106
• Description: Animas-La Plata
• State: CO
• Basin: San Juan/Dolores
• Water Division: 7
• Date: 1/1/1996
• Title: Correspondence regarding the Final Supplement to the Final Environmental Statement
• Water Supply Pro - Doc Type: EIS

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8-16-96 4:52PM; 970 385 6539 ->
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303 866 4474;

#17/22

SENT BY: BOR-WCAOS SD;

SWQBINMED Summar}-
August 12, 1996
Page 15

tnlllmVit of Irrifltlliml ,,""rII/luws, The purpose of the cn,.jromnenta! impar.t JIroC"ss is to avoid
these effects during the planning phase prior to any construction.

These conol\1l1ioDli compare the Project soib to soils with contents commonly ranging up to 80,000
ppb and then conclude that "total selenium found in soils is comparatively low throughout the
Project" and that "loog-tenn impacts to in'igation rer.um flow water quality are expected to be low."
WI do not flI711,

l:nntAm;nSlfttlnapact A~vu:mm1t

The A./i.,essment found that, with the: exception of mercury, mean concentrations of l!to: .lililiUl vw
trace elemCllts never exceeded the EP A aquatic life criteria. The Assessment considers that
contaminatiOl1 of the mercury samples collected from the La Plata River durina this study is a
possibility. Once again, there ere me,jor problems with this Assesmlent. Geometric MCMS of data
are used for comparison to the EP A aquatic life criteria in order to ddlllIlline potential problems.
No comparisons are made with the New MCltico water quality standards and no comparisons are
wade using the actual individual sample resul~. The Assessment assumes that only the dissolved
frl1Ouon of the water "conWlllI those elements that are potentially bioavailablc and mar result in
toxicologic.a1 responses in an aquatic ecosystem.." Wl! tIIJ ._,7ft wlti tIt& _1UIIpIID1C tIS 811D_
by tlu, Stm IIIDIdJuds wldcft.JtH' """IIIY tlIUI ulnIiIurI, rezaltlk two diflt!fe1lt "total" /NlJ:liDl/S,

Table 13 (Pllie 50) lists the total nwnbers of samples and the maximum concentrations of seven
dissolved tral:e elements in the La Plata River and compares these to tho BPA aquuic life CriteriL
The maximum concen1ration of dinolved selenium was 9 /-LiIL, 4,5 times tbll New Mexico water
quality standald for total recovenble !lelenium, !be maximum concentration of dill.~lved mereury
was 0.4 I-LgfL, 33 times the New Mexico Water quality standard for IQ1al mercury, No other
dissolved trace elements reportedly exceeded the F.P A aquatic life ctiteria in the La Plata Rh-er,

Table 14 (pIae 51) This table lists the llcometric: means of dissolved elements in samples from the
La Plata Rinr. The AssessmDllt dt:lerminelllhal "[h]azard quotients for the &eOmetric mean
COD.ceutrations of dissolved element3 (in the La Plata River] inditatcd that, coppc:r and selenium were
low hazards JUggesting that some potential for sublethal effects should be considered." The
i""'mmric. me""" of dissolved mercury for the La Plata River in New Mexico are an order of
magnitude above the EP A lICluatic life criterion for IDllIClII)' and an order of magnitude above the
New Mexico water quality stuldcd for kI1il mercury. Based on the geometric mean of the dissolved
mercury concenlrll1iOlll!l. the Assessment detmnined that mP.1'ClIrV ~rflV;Tltto-il a mnderate h"7.1.d to
aql."tic lif;. The Assessment states that "{m]ercury concentrations in fish tissues would not be
expected to elluse adverse efl'Kts on the fish ~mmun1ty, but do ~sent a hA7"rd to fish_tin"
birds and mammals in the lII'llIl," preSUJJlllbly iDcludina humans, [Emphasis added] We mll8t again
roitcrate t1ll!t individual values were nor comp~ to the New Mexico standards and that use of only
dissolved values is of little value in detenninina the likely impa'la from this proposed project.

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