Characterization of water quality of Highline Reservoir
Characterization of water quality of Highline Reservoir and evaluation of the effects of increased residence times on the quality of water in Highline Reservoir, near Grand Junction, Colorado
Study Area: Statewide
Highline Reservoir is located about 20 miles northwest of Grand Junction, Colorado. It has a surface area of about 160 acres and a storage capacity of about 3,400 acre-ft. Water is released from the reservoir through the reservoir spillway and a bottom outlet exists for emergency storage evacuation purposes. The reservoir is used primarily for recreational purposes including swimming, boating, water skiing, and fishing. Historically, more than 10,000 acre-ft of water has been spilled to the reservoir between August and November each year. This water enters the reservoir at Mack Wash through the Camp 7 Dump, a diversion off the Government Highline Canal that diverts water from the Colorado River downstream from Cameo (see study area map). Depending on stratification patterns, the "spill water" results in short residence times and rapid flushing of either a) the entire volume of water in the reservoir or, at a minimum, b) rapid flushing of the epilimnion, the water in the upper stratum of the reservoir above the thermocline.
Currently, an agreement is being negotiated that would, over a 3-year period, decrease the amount of water diverted to the Government Highline Canal. Reduced flushing and dilution of the reservoir could adversely affect bacterial populations at the swim beach and may adversely impact other recreational use(s) of the reservoir.
As a result, the Department of Natural Resources for the State of Colorado requested the USGS to prepare a plan of study to evaluate limnological conditions prior to implementation of the management plan. An evaluation of changes in limnological and water-quality characteristics that may occur from increasing the residence times due to changes in operation of the Highline pumpback are also addressed in the study plan.
The overall objective of this study is to evaluate the water quality of Highline Reservoir with particular emphasis on evaluating changes in water quality once the Highline pumpback becomes operational. Specifically, the objectives of this study are: