Total dissolved solids (TDS) – a measure of water quality – is a source of concern for Aspen Park and Conifer Metro District activity centers.

As we explain in Water Quality Monitoring, TDS comes from many sources including geologic formations in the watershed, wildlife activity and human activity.

TDS includes the following:

  • Minerals that are dissolved as surface water flows from above ground to our fractured crystalline bedrock aquifer, through geologic formations in the watershed. Some examples of minerals in our water include: chloride, bicarbonate, sodium, calcium, magnesium, and iron.
  • Human sources include discharge of wastewater from individual and community water treatment systems, stormwater runoff from developed areas, and road de-icing. Other examples of human-caused TDS include soaps, shampoos and cleaning agents.

The federal secondary standard for TDS in drinking water is 500 milligrams per liter (mg/L) and Colorado has set a groundwater standard of 400 mg/L. The Colorado standard in groundwater comes into play with discharge of treated wastewater to groundwater. Conifer Metro District (CMD) and Aspen Park Metro District (APMD) both have systems that discharge treated wastewater to groundwater.

The below graph shows TDS for both systems have been steadily increasing.

Conifer is a well-based community, so recharge to the fractured-rock aquifer is crucial to sustainability

Reverse Osmosis (RO) systems are used by several CMD users (Safeway, etc.) to reduce TDS levels for customers. The brine removed from the water, however, is returned to the collection system and recharged into the aquifer.

CMD has a permit to discharge through its exfiltration gallery but has been exceeding the 400 mg/L standard since it was imposed. The district has been under an order from the Colorado Department of Public Health and Environment to remedy the situation. To address the TDS exceedance, CMD considered a surface discharge of the processed effluent and has requested a variance to allow discharge to groundwater at concentrations above the current standard of 400 mg/L.

To achieve compliance with the CDPHE Discharge Permit, CMD is requesting a change in limits to 1663 mg/L.

During the CDPHE open public comment period, the CAC Water Team suggested that TDS levels above the SMCL require periodic analysis of the TDS composition as opposed to a violation and cease and desist.

CAC is following this issue and recognizes that elevated TDS in the groundwater and surface water is a key water quality concern for residents.

Increased salinity in ground water is a broader issue in mountain communities. The Water Team has an on-going interest in identifying solutions to address or minimize the increasing TDS levels in the community. Centralized systems are a point source that may have technical solutions and we recognize there are many sources in addition to the centralized systems including, but not limited to, roadway de-icing applications and individual wastewater systems.

Data and interpretations on this website are presented for general information only. This is a compilation of data from multiple sources and the compilers cannot ensure accuracy. Contents are continuously updated and the compilers strive to provide the best data possible but Conifer Area Council does not assume responsibility for use by others.