State lawmakers are seeking to tack on a $12 million amendment to Gov. Deval Patrick's $1.4 billion environmental bond bill. The amendment would potentially include $7 million for the removal of pollutants, known as PCBs, from the Neponset River's sediments, with the rest potentially going for "fish ladders" and the exploration of the removal or maintenance of two state-owned dams in order to aid the return of herring and shad runs.

The Neponset River Watershed Association is mounting a push to get the amendment added to the bill, asking environmental advocates to call their senators and representatives. The vague wording of the amendment would give the governor flexibility to spend it on the Charles or another river if he wanted to, advocates say.

"This doesn't force him to spend it on the Neponset," said Steven Pearlman, an advocacy director with the watershed association. Bonding bills are essentially bills that give the executive branch the authority to borrow money.

One of the lawmakers pushing the amendment is state Sen. Brian Joyce (D-Milton), the vice chair of the Legislature's bonding committee. The bill has already cleared the Joint Committee on Environment, Natural Resources and Agriculture and was heard by the bonding committee last week.

"This is an opportunity to clean up what's been an environmental problem for a long time," said state Sen. Jack Hart, a Dorchester Democrat of the amendment's PCB-cleaning component. But Hart added that when it comes to removing dams, a community debate is needed, since the two dams - Tileston-Hollingsworth Dam and the Baker Dam - potentially hold some historical value.

The amendment would allow for the funding of a citizen advisory committee tasked with taking up the Neponset River's restoration. More information on the bond bill can be found at envirobond.org.