MONITORING PROGRAM

The Big Dry Creek monitoring program currently focuses on the main stem of Big Dry Creek, but has also included Walnut Creek in the past. Additionally, the U.S. Department of Energy monitors conditions on the Rocky Flats property, the Standley Lake Cities monitor conditions in Standley Lake, and Broomfield monitors Great Western Reservoir and Walnut Creek.

The central focus of the monitoring program is the main stem of Big Dry Creek in accordance with the Big Dry Creek Sampling and Analysis Plan.  Data collected under this monitoring program are entered into a master database following QA/QC by the steering committee. This database is currently in Microsoft Access in a STORET-compatible format (SIM, or STORET Interface Module). On an annual basis, the water quality data are retrieved from the database and compared to Colorado Water Quality Control Commission stream standards to assess whether the stream is attaining stream standards. Trends regarding water quality and flow are identified and discussed in an annual technical memorandum presented at a Watershed Association meeting and are subsequently summarized in a Watershed Association newsletter. Additionally, data stored in the Watershed Association database have been provided to the Colorado Water Quality Control Division on several occasions in support of development of the state's 303(d) list and development of preliminary effluent limits for municipal wastewater discharges in the watershed.

The monitoring program includes water chemistry, flow, habitat, fish, and benthic macroinvertebrate sampling. Additional special sampling has also been conducted for E. coli and selenium.  Artificial substrate sampling was also conducted for several years. An overview of the program is provided below. Water chemistry monitoring has been conducted for nearly 20 years. The aquatic monitoring program began in 1997 to document the abundance and distribution of fish and benthic macroinvertebrate populations and to describe the physical habitat at select locations in Big Dry Creek.

Objectives of this monitoring program include establishing a database that can ultimately be used to determine appropriate surface water quality standards for Big Dry Creek and document the effects of potential influences in water quality on the aquatic community. Under the current monitoring program, benthic macroinvertebrates, fish and habitat data are collected in the fall biannually. Historically, annual biological monitoring was conducted in both the spring and fall.  Aquatic Associates is the contractor responsible for the aquatic monitoring activities. See the Watershed Management Plan (Wright Water Engineers 2002) for more detail on the program. constituents monitored and sampling frequency for the main stem of Big Dry Creek as of 2008 are listed below.  Ten locations are monitored, including seven instream locations and three wastewater discharges.   The monitoring program is reviewed and revised as needed on an annual basis.  Additional samples are periodically collected to supplement the routine ambient monitoring program.