9-10 Excellent Exhibits almost no impact. One factor was the continued elevated levels of salinity in the water in this region. Salt deposits left behind by ancient seas and methods used to extract oil and gas from wells in the drainage area upstream continues to enter the Colorado basin and require constant monitoring for salinity. Elevated levels of salinity can remain in area waters, and even increase during hot, dry weather as evaporation leaves concentrated levels of salts behind. The second factor was the amount and location of rainfall and resulting runoff of pollutants.
Heavy rains can carry sediment, nutrients, and bacteria into surface waters.
These pollutants affected water quality briefly in March, contributing to localized algae blooms in Lake Buchanan during April. The third factor contributing to the water quality rating in this region was the summer phenomenon in which the lake forms two layers, a warmer layer over a cooler one. Overall, the waterways of the upper region of the lower Colorado River basin were able to assimilate both the natural and manmade influences encountered during the year with minimal negative effects. The water quality rating of 8 is the same as 1997. Since dissolved oxygen is replenished naturally, the headwaters of Inks Lake are affected more than the lake further downstream near Inks Dam.