Stormwater Master Plan

Evaluation of the stormwater system to identify problems and plan for future community needs.

Share Your Experience by dropping a pin on the map where you have seen stormwater issues.

Stormwater management in Marion is evolving to meet the needs of our growing City.

We are developing a stormwater master plan to ensure the community's assets are managed effectively and enhance stewardship of our environment.

What is a Stormwater System?

Stormwater is the runoff from rain or snowmelt that is not absorbed by soil. Stormwater can flow directly to streams and lakes, or it may be transported by municipal storm sewer pipe systems. Unlike sanitary sewers, storm sewers do not lead to treatment plants but eventually drain into streams and lakes.

As communities grow, they often experience more stormwater runoff issues, such as:

flooding
streambank erosion
damage to public and private property
poor water quality

A new Stormwater Master Plan is crucial to understand the current state of the storm-water system and provide a future plan for growth that reduces the risk of stormwater run-off issues.

Stormwater Infrastructure

Stormwater infrastructure is categorized into publicly-owned and privately-owned. The City is required to operate and maintain all publicly-owned infrastructure. Infrastructure that is privately owned should be maintained by entities such as homeowners associations, developers, or property owners. This study will be focused on publicly-owned infrastructure. If you have issues with privately owned infrastructure, please review City Code 274-20.

Storm Intakes

A drain designed to remove excess rainwater from areas that do not drain on their own, such as paved streets, parking lots, and backyards.

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Storm Sewer Pipe

Underground pipes that collect rainwater from storm intakes and transport it to nearby drainageways and creeks.

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Drainageway

A natural or constructed channel that moves water overland to a nearby creek or river.

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Culvert

A culvert helps move water from one side of the road to the other.

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Detention Basin

An excavated area designed to fill with water and protect surrounding property and infrastructure from damage.

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A New Stormwater Master Plan

A stormwater master plan (SMP) is an essential first step towards managing the City's stormwater infrastructure. The SMP project will occur in three phases:

SMP Project Phases

Phase 1: State of the System - We are here

This data gathering and evaluation phase focuses on documenting the current state of the City's stormwater system.

We will be collecting all available information regarding the stormwater system, including:

GIS data
prior studies
operations and maintenance efforts
documented issues from residents

Then we'll develop a computer-based model that replicates the City's real-life stormwater system. This information will be used to help us determine where current issues (like excessive ponding, erosion, and public safety hazards) might be occurring throughout the City.

Planned Completion: Summer 2025

Phase 2: Improvements & Planning

This phase includes development and prioritization of improvement projects that are needed to address infrastructure issues. This phase will also evaluate and plan for future needs to ensure sustainable and effective development as the City continues to grow.

Planned Completion: Spring 2026

Phase 3: Study Complete

This phase will provide a capstone report that documents the information, analysis, and recommendations from phases 1 and 2. It will provide the City with a plan for future stormwater management.

Planned Completion: Summer 2026

This SMP is not an evaluation of flooding within the floodplains defined by the Federal Emergency Management Agency (FEMA). Our focus is primarily on the stormwater system within the City's built environment (the areas within the City that drain to the major creeks). We will not be focused on flooding that occurs on Indian Creek, Dry Creek, Coopers Creek, or Wanatee Creek, although we will use information from previous FEMA studies to inform this project.