Northwood Lake Stormwater Improvements, New Hope, Minnesota

A case study of Northwood Lake (New Hope, Minnesota) low impact design (LID) stormwater improvements will be presented. The goals of the project were to: (1) Improve the water quality of stormwater that previously drained untreated to Northwood Lake; (2) Minimize environmental impact to one of the City’s flagship parks; (3) Inform and engage the Friends of Northwood Lake Association and surrounding residents about sustainable stormwater management practices; and (4) Promote collaboration on stormwater management issues among the Basset Creek Watershed Management Commission, the City of New Hope Public Works Department, and the City of New Hope Parks Department.The project involved the planning, design, and construction of various BMPs throughout the Northwood neighborhood. A 160,000 gallon underground concrete vault collects stormwater and reuses it to irrigate adjacent ballfields. Rain gardens treat overflow from the vault. Sump manholes with skimmer structures were installed prior to the stormwater discharging into Northwood Lake. A stormwater pond in addition to underground trenches was installed to collect and treat stormwater runoff from surrounding neighborhoods. The goal of constructing these various BMPs in areas that discharge to Northwood Lake was to reduce total phosphorus, total suspended solids, and stormwater volume to the lake.Construction in the area was done in three phases; the first two phases were substantially completed in 2016 and the third phase was substantially completed in 2017. The majority of the stormwater BMP construction was completed in 2016, with the exception of linear underground trenches that were constructed in 2017 as street reconstruction occurred. Following construction of these BMPs, monitoring of the underground storage tank has been conducted to determine the amount of stormwater used to irrigate the ballfields. Funding was provided by the City of New Hope, the watershed district having jurisdiction in the area (Bassett Creek Watershed Management Commission), and two state agencies. The two state agencies that contributed funding were the Minnesota Pollution Control Agency (MPCA), through a Clean Water Partnership Grant, and the Board of Water and Soil Resources Clean Water Fund grant.The presentation provides an overview of water quality issues in the Northwood Lake area, details design considerations for the project, and discusses collaboration and educational opportunities between various agencies. In addition, an overview of the lessons learned from design and construction phases will be discussed.