Sewage overflow is a big concern for many people in Massachusetts who live near waterways.

According to the Massachusetts Rivers Alliance, the commonwealth's waterways receive almost 3 billion gallons of untreated and partially treated sewage and stormwater from combined sewage overflow outflows in a typical year.

To help alleviate the problem, several organizations are working together to support House Bill 886. The proposal would help prevent overflow in Massachusetts Water Resources Authority sewer service areas, except in the biggest storms, which advocates say would better protect communities most impacted by pollution.

At a virtual meeting on Thursday, Katharine Lange, the policy director at the Mass. Rivers Alliance, said sewage overflow is a problem for several reasons, including environmental justice and public health concerns.

“As climate change escalates, as our precipitation trends grow more intense, as our rains become flashier, with that comes more sewage pollution,” she said. “Because, again, our water infrastructure was not built for these new trends that we’re experiencing. It can only carry so much water at a time. So, unfortunately sewage pollution is occurring more frequently with the more rain that we’re experiencing.”

One major problem with combined sewage overflow systems is that they disproportionately impact marginalized communities.

Nathan Sanders, a data scientist at the Berkman Klein Center at Harvard who works with the Mystic River Watershed Association, said a person's ZIP code shouldn’t determine their exposure to sewage pollution. But analysis of data made available after the statewide sewage notification system went online last year shows the opposite.

The data shows areas with more non-English speakers, people who live in poverty, and people of color all have notably higher amounts of sewage discharge.

For a watershed that has two times as much linguistic isolation — meaning a larger fraction of households whose adults speak English less than very well — as another watershed, it will on average have 1.8 times as much sewage discharge.

If a watershed has two times as many people in poverty, it will on average have 3.4 times as much sewage discharge.

And if a watershed has two times as many people of color, it will on average have 4.4 times as much sewage discharge.

“Our environmental justice communities deserve action on this front,” he said. “We have an obligation to provide an equitable distribution of the burdens of environmental pollution, including sewage discharge and we can take action to make progress towards that.”

Eugene Benson with the group Save the Alewife Brook said that federal law won’t fix the combined sewage overflow issue, pointing to limits in restrictions at the federal level.

“Now’s the time for the Legislature to act,” he said. “There’s no federal pre-emption. States can be more protective of their environment and their residents than required by the federal Clean Water Act. States can hold themselves and their entities, cities, authorities, et cetera, to higher standards than federal requirements. And we know more about the terrible impacts of CSOs on public health and on environmental justice populations.”

A hearing on House Bill 886 is scheduled for next week at the State House.