Most larger private foundations have already told the IRS they won't read your proposal. Each state guide counts how many, then lists ten to fifteen secular funders of environmental and conservation work in that state that do take applications, with what they fund, what they have given, and when they next open.
Every private foundation files Form 990-PF with the IRS each year. Part XIV, line 2 has a checkbox a foundation ticks when it "only makes contributions to preselected charitable organizations and does not accept unsolicited requests for funds." For each state, I read the most recent e-filed return of every private non-operating foundation with $1 million or more in assets and count how many tick it. That is the percentage shown for each state.
From the foundations that leave the box empty, and from community foundations, public grantmakers and government programs, I keep only secular funders that paid grants to environmental or conservation groups in their latest filing. Every deadline is labeled: Verified (on the funder's own site on the date checked), Expected (based on last cycle), Rolling, or Filing only (no website). Each guide shows the date it was last checked.
States without a guide yet are marked coming soon.
They are not exhaustive and they are not rankings. Deadlines and guidelines change, so open each funder's own page before you start. Grants are competitive, and past grant sizes describe what a funder gave, not what it will give you. I list secular funders only.
A Funding Roadmap ($1,200, flat fee) gives you ten to fifteen funders matched to your mission, place and size, the grants each one paid to groups like yours, how to apply, and a 12-month grant calendar. Every deadline is labeled the same way as in these guides.