Water quality in a stream is influenced by human activities (upstream land and water uses) and natural geological weathering and biogeochemical processes. All water is of a certain quality, and data and regulatory standards measure its suitability for a particular use (like drinking, swimming, or industrial processing) based on physical, chemical, and biological characteristics.
Water quality in streams supports recreational uses, ensures public health, and supports wildlife and fish habitat. Water quality is usually the most monitored aspect of stream health due to the existence of regulatory standards. The Colorado Department of Public Health and Environment’s Water Quality Control Division has a number of programs that implement the federal Clean Water Act, the federal Safe Drinking Water Act, and the Colorado Water Quality Control Act. Stream Management Plans typically use these regulatory frameworks to assess water quality, but the departure from natural conditions (regardless of whether a standard is exceeded) can also be factored in.
Assessing existing or historical water quality conditions is fairly straightforward if there is a history of data collection. Typical parameters assessed include temperature, nutrients, other inorganic compounds, and metals. Much of the water quality data in Colorado is publicly accessible via the Colorado Data Sharing Network, and the list of stream segments not in compliance with state standards (Section 303(d) list) is updated every other year. Water quality data collection need not be left to the professionals – Colorado River Watch organizes 2,500 citizens to collect and report water quality on their home waters.
Water quality data on metals, nutrients, temperature, pH, dissolved oxygen, and inorganic compounds
Attainment of water quality standards
Effluent discharge permit violations
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Pollution sources are classified as point or nonpoint. As defined by the Clean Water Act, point sources are any discernible, confined, and discrete conveyance from which pollutants are or may be discharged. Nonpoint sources are any source of water pollution that does not meet the legal definition of “point source” in the Clean Water Act. Nonpoint sources can include excess fertilizers, herbicides and insecticides from agricultural lands and residential areas; sediment from improperly managed construction sites, crop and forest lands, and eroding streambanks; or bacteria and nutrients from livestock, pet waste, and faulty septic systems. Point sources are directly regulated by the Clean Water Act through permits, while nonpoint source regulation has largely been left to each state. In Colorado, the Nonpoint Source Program tracks the reduction of phosphorus, nitrogen, and sediment loads and the restoration of impaired waterbodies. It also provides outreach, technical assistance, and funding for local groups to plan, design, and implement various efforts to address nonpoint source issues that are degrading water quality. If your watershed has a nonpoint source watershed plan in place, Non-Point Source Program funding can be used for further study or project implementation.
If you collect new water quality data, standard collection practices exist for data on metals, nutrients, water temperature, pH, dissolved oxygen, and inorganic compounds outlined in the Colorado Water Quality Control Division’s Regulation No. 31-The Basic Standards and Methodologies for Surface Water.
EPA’s Better Assessment Science Integrating Point and Nonpoint Sources (BASINS) assists in watershed management and total maximum daily load (TMDL) development by integrating environmental data, analysis tools, and watershed and water quality models. With BASINS, users can efficiently access national environmental information, incorporate local site-specific data, apply assessment and planning tools, and run a variety of proven, robust nonpoint loading and water quality models.
Water temperature standards in Colorado streams protect aquatic life, and are therefore relevant to SMPs that aim to protect or enhance fisheries. Elevated temperatures can kill fish or decrease their growth and reproduction rates. There are both chronic and acute temperature standards. Colorado has approved methods for temperature data collection, as well as a list of stream segments that exceed standards.
Collecting additional water quality data for an SMP doesn’t have to be complicated. There are many places where local volunteer groups collect temperature data as part of watershed planning, for example. Best practices for collecting Citizen Science data are outlined in River Network’s Science and Technical Resources Portal.
State of the Poudre River
Assessment Level: Level 2
The City of Ft. Collins determined water quality conditions by evaluating one year of data for temperature, nutrients, pH, and dissolved oxygen at eight monitoring sites. The sites were evaluated by comparing data to specially-developed grading guidelines for water quality. The guidelines took into account departure from natural conditions and exceedance of water quality standards. An overall water quality indicator grade was calculated for each of the 18 reaches in the assessment report.
City of Steamboat Springs Yampa River Health Assessment and Streamflow Management Plan
Assessment Level: Level 3
Water temperature data indicated regular exceedance of standards. The City sought to understand the potential for using streamflow management and riparian restoration to control water temperature during late summer peaks. These actions were investigated using (1) models of observed streamflow, water temperature, and air temperature from several locations on the Yampa River; and (2) an energy balance model for water temperature. This approach helped identify the types and locations of management activities most likely to decrease summer river temperatures. Appendix E, Water Temperature Management Opportunities outlines the assessment methodologies, the results, and the management implications.