Connecticut laws/regulations; Other States laws/regulations;

OLR Research Report

December 19, 2011




By: Lee R. Hansen, Legislative Analyst II

You asked for a comparison of the laws and regulations in Connecticut and its neighboring states that require utilities to trim the trees around their power lines.


Connecticut's laws and regulations regarding electric company tree trimming and vegetation management are generally similar to those of its neighboring states. Neither Connecticut nor any of its neighbors mandate utility tree trimming cycles or line clearance specifications for their electric companies. Instead, they generally require them to submit a plan for tree trimming and vegetation management that must be approved by each state's respective utility regulating body.

Although each company develops its own plan, subject to state approval, they tend to maintain an eight- to 10-foot clearance around the sides and bottom of a power line and a 12- to 15-foot clearance above it. Trimming cycles range from every four to seven years, with additional trimming and vegetation management for areas that have been problematic in the past.


Connecticut law requires electric companies to prepare an annual plan for maintaining its poles, wires, and other fixtures along public highways or streets that are used to transmit or distribute power (CGS 16-32g). The plan must include a (1) summary of appropriate staffing levels needed for maintaining the fixtures and (2) program for trimming branches and limbs located near overhead electric wires that may damage them. The Department of Energy and Environment Protection (DEEP) reviews each company's plan and may issues orders as it deems necessary for compliance. It can also require an electric company to submit an updated plan containing information prescribed by DEEP.

In practice, Connecticut Light & Power (CL&P) normally trims trees near its distribution lines every five years. Trees are trimmed to clear eight feet from either side of the line, 10 feet below the line, and 15 feet above it. Trees in areas subject to frequent outages are trimmed to 20 feet above the line. For more information on the state's general tree trimming laws and CL&P's tree trimming program, see OLR Report 2011-R-0330.


In New York, tree trimming legislation focuses primarily on maintaining electric transmission, rather than distribution, lines. Transmission lines move large amounts of high-voltage power long distances and are typically strung on tall steel or wooden structures with wide rights of way around them. Distribution lines bring the power in lower voltages from substations to local homes and businesses over the utility poles that line most streets.

The New York Public Service Commission (NYPSC) requires each of the state's electric utilities to submit a right-of-way management program for its respective transmission system. Among other things, the program must provide for (1) regular inspections of the system, (2) specific quantitative criteria for the clearance between the lines and surrounding vegetation and the corresponding time in which trimming must be performed, and (3) annual trimming schedules based on inspection results (16 NYCRR 84.3). NYPSC conducts an annual review and assessment of the program, including a field inspection of a portion of the utility's right-of-way system; a tree-caused outage assessment; and analysis of expenditures, staffing levels, acres treated, and customer complaints.

New York does not specifically regulate tree trimming for its electric distribution system, although a cursory survey of its electric distribution companies indicates that they generally seek to maintain a 10-foot clearance to the sides and underneath a line and a 15-foot clearance above it. There does not appear to be any standardized trimming cycle.


Massachusetts, through regulatory rulings by its Department of Public Utilities (DPU), requires its electric companies to establish and maintain comprehensive tree trimming and tree monitoring programs. The companies must also conduct annual meetings with the local municipal tree wardens of each municipality within its service territory and conduct educational campaigns to educate the public about the danger trees pose to service lines (DPU 91-228). In addition, DPU requires each company to submit an annual reliability report which includes vegetation management plans and activity over the previous five years. The Massachusetts DPU also considers a company's tree trimming and monitoring program's effectiveness when it examines reliability issues during rate cases or investigates storm responses (see DPU 09-01-A, Winter Storm 2008 investigation).

Massachusetts law additionally requires its electric companies to provide copies of their five-year vegetation management plans and yearly operating plans to the state's Natural Heritage and Endangered Species Program and Department of Agricultural Resources. Both agencies must approve the programs and plans before the company can commence any vegetation management activities, although they primarily on the use of herbicides in transmission line rights-of-way (321 Code of Mass. Regs. 10.68; 333 Code of Mass Regs. 11.00).

In practice, the state's electric companies, such as N-Star and Western Massachusetts Electric, try to maintain an eight-foot clearance to the sides of a distribution line, an eight- to 10-foot clearance below it, and a 12-to 15-foot clearance above it. The companies' stated maintenance cycle is every four to six years.


Under a Rhode Island law enacted in 2010, electric companies must provide the state's Public Utilities Commission with a report on their vegetation management operation and maintenance expenses as part of a larger proposal to decouple the utilities' revenues from sales. The commission must review and approve the plan and ensure that the companies maintain reasonable and adequate service quality standards after decoupling (R.I. Gen. Laws 39-1-27.7.1). The state's law does not require any further review of tree trimming or vegetation management plans, although related expenses are part of the state's regulated rate making decisions.

In practice, National Grid, which serves the overwhelming majority of the state, tries to trim trees on a five to seven year cycle and maintain a 10- to 15-foot clearance in every direction from the power line.