Urban Drool Water Quality in Denver, Colorado: Pollutant Occurrences and Sources in Dry-Weather Flows

Abstract

Dry-weather flows in urban channels and streams, often termed “urban drool”, represent an important source of urban surface water impairment, particularly in semi-arid environments. Urban drool is a combination of year-round flows in urban channels, natural streams, and storm-sewer systems (runoff from irrigation return flow, car washes, street cleaning, leakage of groundwater or wastewater into streams or storm sewers, etc.). The purpose of this study was to better understand the extent and sources of urban drool pollution in Denver, Colorado by identifying relationships between urban catchment characteristics and pollutants. Water-quality samples were taken throughout Denver at urban drainage points that were representative of a variety of urban characteristics. Samples were analyzed for total suspended solids (TSS), coliforms, Escherichia Coli (E. coli), nutrients (nitrate, phosphorus, and potassium), dissolved and total organic carbon, and dissolved and total recoverable metals. Results from this study were as follows: (1) most contaminants (nitrate, phosphorus, arsenic, iron, manganese, nickel, selenium, and zinc) were concluded to be primarily loaded from shallow groundwater; (2) anthropogenic effects likely exacerbated groundwater pollutant concentrations and contributions to surface water; (3) nitrate, nickel, and manganese may be partially contributed by industrial inputs; (4) medical marijuana cultivation sites were identified as a potential source of nutrient and zinc pollution; (5) E. coli was a ubiquitous contaminant in all urban waterways; (6) erosion of contaminated urban soils, presumably from construction, was found to significantly increase concentrations of TSS, total phosphorus, and total metals. Increasing urbanization and predicted drier climates suggest that dry-weather flows will become more important to manage; the results from this study provide insight on dry-weather water quality management for the City and County of Denver.

Evapotranspiration of Residential Lawns Across the United States

“…While we did not measure the irrigation rates of the households in the present study, the lack of positive correlation between ET inst and VWC indicates that ET of residential lawns was not limited by soil water supply. Hence, residential lawns received either sufficient or excessive amounts of water from precipitation, irrigation, and possibly other urban water sources (D’Aniello et al., 2021; Hibbs & Sharp, 2012; O’Driscoll et al., 2010; Pilone et al., 2021). Baltimore was the only city where ET inst was correlated with VWC.…”

Potential Climate and Human Water-Use Effects on Water-Quality Trends in a Semiarid, Western U.S. Watershed: Fountain Creek, Colorado, USA

“…The focus of the study was on effluent discharge, but urban nonpoint sources can also contribute substantially to nutrients [58]. Distinguishing between the two was beyond the scope of this study [50].…”

Urbanization and Water Management Control Stream Water Quality Along a Mountain to Plains Transition

“…During storms, rapid runoff from impervious surfaces can result in rapid transfer of water, sediment, metals, nutrients, and mixtures of contaminants that have been called “chemical cocktails” (Booth, 2005; Kaushal et al., 2020; Walsh et al., 2005). Less is known about baseflow (non‐storm) conditions, though this is a critical period to characterize stream‐groundwater connections and aquatic conditions that dominate most of the time, particularly in arid and semi‐arid environments (Gabor et al., 2017; Pilone et al., 2021).…”