Improving Water Quality in Como Lake

Capitol Region Watershed District (CRWD) was awarded a $1.76 million grant in 2016 through the Minnesota Board of Water and Soil Resources’ Targeted Watershed Program (TWP) funded by the Clean Water, Land and Legacy Amendment for work in the Como and McCarrons sub-watersheds.

CRWD, in partnership with the City of Saint Paul, identified locations for stormwater treatment practices within the 450-acre Como Regional Park. Cleaning up the water that runs off the park land before it reaches Como Lake is a critical component of improving water quality in the lake.

The Challenge

The biggest challenge facing Como Lake today is too much phosphorus, a pollutant carried directly to the lake through runoff in storm drains. Phosphorus comes from decaying organic matter like leaves, grass clippings, pet waste, and soil. Over time, high levels of phosphorus — three times higher than Minnesota standards — have led to algae blooms that choke the oxygen from the lake, leading to fish kills and strong odors mid-summer.

Como Lake is part of Como Regional Park and is surrounded by an urban landscape. Storm water drains from the roads, rooftops, parking lots, and sidewalks and flows into Como Lake, carrying pollutants like phosphorus. In this developed urban landscape there are limited opportunities to capture and clean runoff before it reaches Como Lake.

The Solution

CRWD and the City of Saint Paul assessed Como Regional Park to identify sites to strategically manage stormwater runoff. Sites were prioritized based on their ability to treat runoff before it reaches Como Lake and the availability of suitable land. Stormwater Best Management Practices at two locations within the Como Golf Course were selected, the fairway of Hole 7 and the stormwater pond between Holes 3 and 11.

Hole 7 Fairway

An existing storm sewer pipe near the fairway of Hole 7 captures runoff from 63-acres of land including the zoo and surrounding neighborhood. Water from the pipe will be diverted to an infiltration basin, similar to a large rain garden, and an underground infiltration system. Polluted rainwater will fill the basin and any excess water will flow into a series of underground pipes with thousand of holes in them to allow the water to soak into the ground. Native plants in the basin will soak up water, provide pollinator habitat, and enhance the beauty of the area. The water is cleaned as it moves through the soil, removing pollutants that would have otherwise ended up in Como Lake.

Northwest Pond

Water from 150-acres of land within the Cities of Saint Paul, Roseville, and Falcon Heights drains to a stormwater pond between Holes 3 and 11. An iron-enhanced sand filter will be added along the eastern edge of the pond to remove dissolved phosphorus, a pollutant in the water that fuels algae growth. Iron filings mixed into sand create a bond with phosphorus, removing it from the water before it enters Como Lake.

A smart control system added at the pond’s overflow outlet will help control the level of the pond to optimize the effects of the iron-enhanced sand filter and reduce flooding on the course.

Results 

The improvements are estimated to treat over 1.7 million gallons of water and prevent 55.1 pounds of phosphorus from entering Como Lake each year.

Watch the project in progress!