Successful Project: Tributary Basin By-Pass Project

In an effort to reduce total nitrogen and phosphorus levels in Standley Lake to 1990 levels, in 1991 the City of Arvada began working on ways to reduce loadings of nutrients, metals, oil and grease and other common urban stormwater pollutants coming from an area known as the Tributary Basin.

The Tributary Basin watershed is located between Golden and Standley lakes and covers an area of approximately 20,750 acres.  In 1990, all stormwater from this area drained into three canals: Church Ditch, Farmer Highline Canal and Croke Canal.  These canals then flowed into Standley Lake. Click here to see a map of the basin.

Routing stormwater flows around Standley Lake via construction of multiple by-pass structures was determined to be the best solution.  This was achieved at a total cost of some $1.25 million dollars, and required collaboration with numerous entities including the cities of Golden, Northglenn, Thornton, Westminister, Jefferson County, Farmers Reservoir and Irrigation Company, Farmers Highline Canal, and Jefferson Center Metropolitan District.

As a result of the by-passes installed in 1992, recent computer modeling indicates that even with full development in the basin, there will be no increase in total phosphorus and nitrogen reaching Standley Lake from the Tributary Basin.

In the future, the City of Arvada will be looking at opportunities to construct additional by-passes to further reduce nutrient loading and better manage stormwater.

For more information, contact James McCarthy, City of Arvada Deputy Utilities Manager, at 720-898-7795 or

Below are photos of the new structures on Little Dry Creek and the Church Ditch.
Below Left: Church Ditch at Ralston Creek; Right: Croke Ditch at Ralston Creek