---
title: "The city that's turning its parking lots into sponges"
description: "After three summers of flash floods, Eastvale is tearing up asphalt and planting rain gardens. The early numbers suggest the ground can do what the pipes can't."
date: 2026-11-11
section: "Climate"
authors: ["Priya Raman"]
format: feature
tags: ["cities","flooding","infrastructure"]
url: https://baselayer-blakey-sanity.pages.dev/news/parking-lots-into-sponges/
---

# The city that's turning its parking lots into sponges

The first thing you notice at the old Westgate lot is the sound. Where there used to be the hiss of tires on wet asphalt, there is now the low gurgle of water moving through gravel. Half the lot is still painted with parking lines. The other half is a shallow bowl of grasses, river stones, and young willows.

“We used to watch the water sheet off this lot straight into the street,” says Ana Lindqvist, who runs Eastvale’s stormwater program. “Now it stops here. It sits for a day, and then it’s gone into the ground.”

## Three summers of water

Eastvale’s drains were built for a climate that no longer exists. Three summers in a row, storms dropped more rain in an hour than the pipes could carry in a day. Basements flooded. A commuter underpass filled to the ceiling. The city’s own engineers estimated that replacing the main storm sewers would take twenty years and cost more than its entire capital budget.

So the city tried something cheaper and slower: making the ground absorb more. Planners call it “sponge” design. Instead of rushing rain into pipes, you slow it down, spread it out, and let soil and plants soak it up.

> “The pipes are the last line of defense. We’d been treating them as the first.”

## Asphalt out, gardens in

The program targets the city’s least loved surface: parking. Eastvale has roughly four parking spaces for every car, according to a 2025 municipal survey, and many of them sit empty most of the week. The city offers property owners a deal. Give up a share of your spaces, and the city pays to replace them with permeable paving and planted basins.

Forty-one lots have signed up so far. Sensors in the basins report how much water arrives and how fast it drains. During a storm in August, the converted lots held back an estimated 60 percent of the runoff that would have reached the street.

## What it doesn’t solve

Sponge design isn’t a cure. Clay soils drain slowly. Basins need weeding, and a neglected rain garden becomes a mosquito pond. And the biggest storms still overwhelm everything.

Lindqvist doesn’t oversell it. “We’re buying time,” she says. “Every lot we convert is one less pipe we have to rebuild in a hurry.”

On a gray Tuesday, a man walks his dog along the edge of the Westgate basin. He’s lived across the street for thirty years. “I miss the parking,” he says, then shrugs. “I don’t miss bailing out my basement.”