From 9News.com:
9NEWS received multiple newstips from hikers and bicyclists near Globeville Landing Park wondering about the green substance, which flowed from a box culvert near 38th St. and Arkins Ct. in Central Denver…
Denver Wastewater employee Al Ortiz said his crew had to pull about 30 manhole covers along the storm drain line to determine the origin of the green substance. Ortiz was unaware whether anyone from Denver Parks and Recreation had notified his division about the draining of the lake.
More water pollution coverage here.