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. 0274 August1997. ... .. 17 . COLORADO WATER land surface. In three reaches of the river - from Pueblo to the Fort Lyon headgate. from the Fort Lyon headgate to John Martin Reservoir, and from John Martin Reservoir to the state line - there has been an average rise in water level. The largest average rise is in the reach from the Fort Lyon canal headgale to John Martin Reservoir. This is the focus of some interest. especially by the Colorado Water Conservation Board right now, in trying to determine the causes and possible ways to mitigate the situation. I want to tallc to you today about water quality in the basin. We have collected data over the years, much of it between 1990 and 1993, as pan of a study that involved aboUI 15 differem emities in the basin. Some of this material will not be new to those of you who know about salinity in the Arleansas River (see Figure 2). In the upper basin, salinily. or salts in lhe water. generally are in very low concentra. lions, frequently less than 100 mg per liler. where the drinking water standard is 500 mg per liter. As that water moves. say, between Parledale and PonIand, you gel a 101 of picle- up of salts because of saline sedimemary rocles in that area. Then. through the Pueblo area, most of the lime water is below the drinlcing water standard in the Arleansas River. As the water is used and reused, there is return now and the water goes bacle to the river. Each time that occurs, the salts are concentrated in the waler. We somelimes hear about the salinity of the Colorado River where it goes imo Mexico, and the concerns about that. That is at a level of around 800-900 mg per liter. In the Arleansas Basin, the dissolved solids are generally very high. especially downstream from Pueblo, and increase rapidly. especially downstream from La Juma. There are some other interesting results from water quality studies that we have done in the Arleansas. I will give you a number of highlights. We will have repons coming OUI within the next few months that will give more detail on a lot of these. Between 1990 and 1993, we collected data on metals in the upper basin coming into the Arleansas River from abandoned mines and mine drainages in the area near Leadville. It happened that in 1992 water treaunem plants were installed both on the Yacle Tunnel near Leadville and the Leadville Mine Drainage Tunnel, and so we had two years of data before that occurred and one year of data after that occurred. 4,IlOO en", Ow :H- 0::; en", oW Wl1. >en ....::! 0.. en", !!lC) 0- z:l ..- -::! Oz w_ ::! en co E c <[ en co -' .. Cl :E '0 o t) 3,IlOO 2,000 E co C c - co t) 1,000 ~ 0 ~ U :c .!! 'S: 5 ~ > !!! c Q. 'C - CO co .. t) -~----~---------- -' o . 375 350 325 300 275 250 225 200 175 150 125 100 75 50 25 0 -25 RIVER MILEAGE FROM THE STATELINE Fig. 2. Dissotved Solids in the Arkansas River There was speculation at the time about how much water quality improvement we might see as a result and, in general, the further upstream you were, the more improvemem there was. We saw statistically significant improvement in water quality. Cadmium. copper, lead. manganese and zinc all appeared to decrease in concentrations after those treaunent plants went on.line. In general, those effects were greater nearer Leadville, and you could not discern effects once you gOl much downstream from Wellsville and, in some cases. even further upstream. There were no exceedences of water quality standards in that one year after we collected data at those sites. AnecdoUlI reports indicate that there have been some improvements in the fishery as a result of this. so this is really good news for the basin! There is another piece of good news in the basin. There is always concern in agricultural areas about whether pesticides are getting into water supplies. We did not do extensive sampling for pesticides. but we did do some sampling for pesticides in the river itself (see Figure 3). (We have not done sampling for pesticides in the groundwater system.) We sampled at four sites, one upstream and three downstream from Pueblo, during the irrigation season when irrigation and applications of pesticides were going on. and again saw good news. Nearly 97 percent of the pesticides analyzed were not detected. Where we did see detec.